JP4619682B2 - Traffic information generation method and apparatus - Google Patents

Description

  The present invention relates to a method for generating traffic information, a device for generating traffic information using the method, and a device for reproducing the traffic information, and it imposes a heavy burden on encoding processing at the time of generation and decoding processing at the time of reproduction. There is no traffic information.

Currently, VICS (Road Traffic Information Communication System), which provides road traffic information providing services to car navigation systems, collects road traffic information from vehicle detectors and image sensors installed on the road. Edit and provide traffic congestion information such as traffic jam information and travel time information indicating the required time through FM multiplex broadcasting and beacons.
In the current VICS information, current traffic information is expressed as follows.
Traffic congestion is congested (general road: ≤ 10 km / h, expressway: ≤ 20 km / h), congested (general road: 10-20 km / h, expressway: 20-40 km / h), light (general road) : ≧ 20 km / h / highway: ≧ 40 km / h), and “Unknown” is displayed when information cannot be collected due to a vehicle sensor failure or the like.
If the entire VICS link (the road position information identifier used in VICS) is the same congestion status,
"VICS link number + status (congested / congested / disturbed / unknown)"
Is displayed, and only a part of the link is congested,
“VICS link number + traffic jam head distance (distance from link start end) + traffic jam tail distance (distance from link start end) + status (traffic jam)”
Is displayed. In this case, when the traffic jam starts from the beginning of the link, the traffic jam head distance is displayed as 0xff. Further, when different congestion states coexist in the link, each congestion situation is described by this method.

In addition, link travel time information showing the travel time of each link,
"VICS link number + travel time"
Is displayed.
The car navigation device using the traffic information holds a digital map database in which a VICS link number is defined in the road network, and identifies a target road of the traffic information from the VICS link number included in the VICS information.

  However, the link numbers defined in the road network need to be replaced with new ones as new or changed roads, and the digital map data produced by each company must be updated accordingly. In this method, the road position is specified with a great social cost for maintenance.

In order to improve these points, Patent Document 1 below proposes a method for notifying a road position on a digital map without using a common link number. In this method, as shown in FIG. 32A, the transmission side sets a plurality of nodes p1, p2,... PN in the road section to be transmitted on the digital map of the transmission side, and FIG. As shown in FIG. 5, “road shape data” is generated by arranging the position data of the plurality of nodes p1, p2,. For example, when notifying the location of the accident that occurred in this road section, this road shape data and the distance from the reference node (for example, p1) to the accident location are transmitted to the receiving side. The receiving side performs map matching that associates each node position included in the road shape data on its own digital map, identifies a road section, and identifies an accident position based on distance information from the reference node.
Patent Document 2 below discloses a method for reducing the amount of data by variable-length coding the road shape data.

JP 2001-41757 A JP 2003-23357 A

As shown in FIG. 33, the currently provided VICS traffic information is a graph in which the vertical axis indicates the number of states (traffic expression resolution) that can be expressed as traffic information, and the horizontal axis indicates the position (or section) resolution. Expressed above, the traffic information can be displayed in 10m increments with respect to the location, but the traffic information can be expressed in only three states: traffic jam, congestion, and light. It is positioned as information with low resolution. In addition, the link travel time can be expressed in units of 10 seconds, but the position resolution is only “link units”, and it is not possible to express the detailed speed distribution in the link. That is, the link travel time information is positioned as information having a low traffic resolution but a low position resolution.
As described above, the current traffic information has two extreme resolutions in information expression, and the intermediate resolution in the circle shown in FIG. 33 cannot be expressed.

  It is possible to collect traffic information within this circle, and the original information collected by existing sensors before editing is based on such intermediate level traffic information, depending on the sensor density. is there. In recent years, a road traffic information collection system (probe information collection system, which collects measurement information such as travel trajectory information and speed from a running vehicle (probe car) and uses it to generate traffic information, which is being researched in recent years. Alternatively, in the floating car data (FCD) collection system), information at each level in the circle can be collected at the center according to the purpose of information collection and the amount of transmission data.

The present inventors have previously proposed a method of setting the position resolution and expression resolution of the traffic information to be transmitted at an arbitrary location in FIG.
In this method, the traffic situation represented by the vehicle speed, travel time, congestion degree, etc. is regarded as a function that changes along the road, and this function is sampled along the road at intervals corresponding to the position resolution. The obtained sampling data is rounded according to the expression resolution. FIG. 34 shows the array (b) of discrete values (sampled data) and the target road (a) thus obtained. The length of one square in FIG. 34 (b) indicates the interval between sampling points obtained by sampling the traffic situation.

The data string of the sampled data is encoded by orthogonal transformation, and the encoded data and road shape data indicating the target road section are transmitted to the receiving side. The receiving side identifies the road section using the road shape data, decodes the encoded data, and reproduces sampled data representing the traffic situation of the section.
Using this method, for example, traffic information of a road section of several kilometers can be encoded to provide information by reducing the amount of data, and the speed measured by the probe car over 4000 m at intervals of 1 second. Information and the like can be transmitted to the center with a small amount of data.
In this case, the longer the target road section of the traffic information is set, the larger the amount of data that can be encoded and compressed, so the data compression rate improves.

The present invention improves this traffic information generation method.
Certainly, when the traffic information is generated by this method, the data compression rate increases as the distance of the target road section increases. However, if the distance of the target road section is long, the following problem occurs.
(1) When encoding and decoding traffic information, the number of samples (data amount) that must be handled together is large, so the burden on the program is large and the implementation of the program is difficult. In addition, it is necessary to increase the memory size of the work memory used for encoding and decoding processing, which is difficult to achieve with a PDA, a low-cost car navigation device, or the like. In addition, it is difficult to perform encoding and decoding processing with a standardized chip.

(2) If the distance of the target road section is long, there is a high possibility that it will include a traffic jam section that requires detailed traffic information and a quiet section that does not require detailed information. It is difficult to change the level of detail (compression rate) of information, and therefore it is difficult to provide detailed information according to necessity.
(3) If the distance of the target road section is long, for example, the distance from the base point transmitted by the transmission side may be greatly shifted on the reception side, and the shift in the distance direction of the road cannot be ignored.

  The present invention solves these problems, and a traffic information generation method that can reduce the burden of encoding processing and decoding processing, can easily change the compression rate, and can correct the deviation in the distance direction. An object of the present invention is to provide a device for generating traffic information by the method and a device for reproducing the traffic information.

The traffic information generation method of the present invention is a traffic information generation method for sampling the traffic situation of a target road at predetermined intervals along the road, and divides the array of sampled data into a plurality of blocks. Encoding is performed by orthogonal transform in units of blocks for the included sampled data.
Since decoding of the encoded data is also performed in units of blocks, the burden of encoding and decoding programs is reduced, and the amount of work memory used for this processing can be small.

In the traffic information generation method of the present invention, the number of sampled data included in each block is set to a predetermined upper limit number or less.
If there is no limit on the number of sampled data included in the encoded data, the traffic information receiving side must adopt a processing system that can handle even if the number of sampled data is large. Is provided, it becomes easy for the receiving side to cope.

In the traffic information generation method of the present invention, the number of sampled data included in each block is set to be constant.
In this way, the decoding mechanism of the traffic information receiving device can be standardized.

Further, in the traffic information generation method of the present invention, the target road is divided at regular distance intervals, and blocks are generated corresponding to the divided sections.
In this way, traffic information encoding / decoding processing can be standardized.

In the traffic information generation method of the present invention, the target road is divided at unequal distance intervals with the selected point as a boundary, and a block is generated corresponding to the divided section.
As this boundary, an intersection or a facility point is selected.
In this method, a section in which a change in traffic flow occurs regularly can be included in one block, and traffic information can be displayed more easily.

In the traffic information generation method of the present invention, the sampled data is divided into time units to generate blocks.
Moreover, when sampling data is the measurement information measured with the probe car vehicle equipment, measurement information is divided | segmented into plurality by the time slot | zone of measurement time, and the block is produced | generated by the divided | segmented measurement information.
In this way, the block may be divided into time units.

Further, in the traffic information generation method of the present invention, when the sampled data is measurement information measured by the probe car on-vehicle device, the traveling information on the probe car on-vehicle device and the position of the probe car on-vehicle device are associated with each other. A block marker indicating the boundary of the block is set based on at least one of position information on map information and communication operation information in a communication unit mounted on the probe car on-vehicle device.
Thereby, for example, a block marker can be set at a change point of a traffic situation according to a traveling state of the probe car on-board device, and the block can be divided, and a change point of traffic information can be easily distinguished.

In the traffic information generation method of the present invention, when a predetermined event occurs in the travel of the probe car on-vehicle device based on at least one of the travel information, the position information, and the communication operation information, the block marker Is set.
As a result, for example, when a predetermined event occurs, such as turning left or right at an intersection or entering a facility, by setting a block marker, the traffic information change point can be easily distinguished, and the section where the traffic situation changes In addition, the block can be divided and set. In addition, even when the measurement information is averaged by performing encoding for each block, the change point of the traffic information can be easily determined.

In the traffic information generation method of the present invention, the data compression rate in encoding is set in units of blocks.
Therefore, traffic information can be encoded with necessary details according to traffic conditions.

The data compression rate is changed according to the average speed of the block represented by the sampled data.
Alternatively, the average speed of the block represented by the sampled data is changed depending on the change rate between the blocks.
Or it changes with the event which has generate | occur | produced in the area corresponding to a block.
Alternatively, in a block including measurement information of the probe car on-board device as sampling data, the block is changed by an event such as a sudden brake measured by the probe car on-vehicle device.
Or it changes with the measurement time of the measurement information which the probe car vehicle equipment measured.
Alternatively, the measurement point of the measurement information measured by the probe car onboard device is changed depending on whether or not it is around the designated position.

Further, in the traffic information generation method of the present invention, when encoding in block units, the block range is expanded, and the sampling data of the block including the sampling data of the extended portion is encoded.
By doing so, it is possible to reduce mismatch (block noise) that occurs at the block boundary when decoding.

In order to reduce block noise, the value of the sampled data in the extended portion is matched with the value of the sampled data at the original boundary of the block.
Alternatively, the value of the sampled data in the extended part is matched with the value of the sampled data corresponding to the block adjacent to the block.
Alternatively, the value obtained by matching the value of the sampled data of the extended part with the value of the corresponding sampled data of the block adjacent to the block, and multiplying the sampled data of the block containing the extended part by the window function Is the sampling data of the block.

In the traffic information generation method of the present invention, position information indicating a block boundary is added to road reference data for specifying a target road to form a part of the traffic information.
The traffic information receiving side can correct the positional deviation in the distance direction of the target road using the position information indicating the block boundary, and can accurately reproduce the traffic information on its own digital map. .

The traffic information reproduction method of the present invention is a traffic information reproduction method in which the traffic situation of the target road is sampled along the road at predetermined intervals, and the array of the sampled data is divided into a plurality of blocks. Traffic information generated by encoding in units is acquired, and the traffic information is decoded in blocks to reproduce sampled data.
Thus, the traffic information is decoded in units of blocks, thereby reducing the burden on the program and reducing the memory capacity of the work memory used for this processing.

In the traffic information reproducing method of the present invention, in reproducing sampled data, traffic information is output in association with position information.
Alternatively, in reproducing the sampled data, the traffic information is displayed on the display means in association with the position information.
As a result, when the traffic information is decoded in units of blocks and reproduced and used such as output and display, the processing load can be reduced.

The present invention also provides a program for causing a computer to execute each procedure of the traffic information generation method described above.
Moreover, this invention provides the program for making a computer perform each procedure of the reproduction | regeneration method of the traffic information in any one of the said.

The traffic information generation device of the present invention is a traffic information generation device that samples the traffic situation of a target road at predetermined intervals along a road, and the array of sampling data corresponding to the traffic situation is divided into a plurality of blocks. Block dividing means for dividing, and coding means for performing coding by orthogonal transform in units of the blocks for the sampled data included in the block.
Thus, by encoding traffic information in units of blocks, the burden on the program is reduced, and the memory capacity of the work memory used for this processing can be reduced.

Further, in the present invention, the traffic information generating device includes a traffic information blocking unit that divides an array of sampled data obtained by sampling the traffic situation of the target road into a plurality of blocks, and encoding of the sampled data included in the blocks. Block-by-block compression ratio determining means for determining the compression ratio in block, block noise reduction processing means for performing processing for reducing block noise generated at the boundary of the block at the time of decoding, and block subjected to block noise reduction processing And orthogonal transform encoding processing means for performing encoding by orthogonal transform on a block-by-block basis.
In this apparatus, traffic information can be encoded in units of small blocks, and the compression rate in encoding can be set in units of small blocks.

Further, the traffic information generating apparatus of the present invention is provided with block position marker adding means for adding position information of a block marker indicating a block boundary to road reference data for specifying a target road, and the orthogonal transform coding processing means generates The encoded data and the road reference data to which the position information of the block marker is added are provided.
The receiving side can identify the target road and the block break from the road reference data.

In the traffic information generating device of the present invention, the block position marker adding means divides the target road at a predetermined distance interval and sets a block marker corresponding to the divided section.
In this way, for example, a block can be divided at a predetermined distance section such as a fixed distance section, and traffic information can be encoded for each block.

Further, in the traffic information generating device of the present invention, the block position marker adding means divides the measurement information at predetermined time intervals when the sampling data is measurement information measured by a probe car on-vehicle device, and divides the measurement information. The block marker is set corresponding to the measured information.
In this way, for example, blocks can be divided at a predetermined time interval such as a fixed time interval, and traffic information can be encoded for each block.

Further, in the traffic information generating device of the present invention, the block position marker adding means, when the sampling data is measurement information measured by a probe car on-vehicle device, travel information on the probe car on-vehicle device, The block marker is set based on at least one of position information on the map information associated with the position of the machine and communication operation information in the communication unit mounted on the probe car on-vehicle machine.
Thereby, for example, when a block marker can be set at a change point of traffic conditions according to the traveling state of the probe car vehicle-mounted device, the block can be divided, and the measurement information is equalized by encoding for each block In addition, the change point of the traffic information can be easily distinguished.

The traffic information reproducing device of the present invention is a traffic information reproducing device in which the traffic situation of the target road is sampled at predetermined intervals along the road, and the array of sampling data corresponding to the traffic situation is divided into a plurality of blocks. An acquisition means for acquiring traffic information generated by dividing and encoding in units of blocks, and a playback means for decoding the traffic information in units of blocks and reproducing sampled data.
Thus, the traffic information is decoded in units of blocks, thereby reducing the burden on the program and reducing the memory capacity of the work memory used for this processing.

In the present invention, the traffic information reproducing device receives the traffic information obtained by dividing the sampled data indicating the traffic condition of the target road into blocks and the road reference data indicating the boundary position between the target road and the block. Each block except receiving means, traffic information decoding means for decoding traffic information in blocks and reproducing sampled data, and sampled data added to reduce block noise from the reproduced sampled data Using block noise reduction processing means for obtaining sampling data included in the range of the road and information on the boundary position of the block included in the road reference data, a correction coefficient for a deviation occurring in the distance direction of the target road is calculated. Using the correction coefficient calculation means for each block and the correction coefficient, the exact position of the block on the target road is identified, and the sampling data is positioned at the sampling position of the block. It is provided with blocks per unit distance correcting means for attaching.
Since this traffic information reproducing apparatus decodes traffic information in units of small blocks, the burden on the program is small, and the memory capacity of the work memory can be small. Moreover, it is possible to accurately identify the block position on the digital map owned by itself using the information on the boundary position of the block, and accurately position the sampling data at the sampling position in the block.

In the traffic information generation method of the present invention, the traffic information of the target road is divided into small blocks and encoded, so the burden on the program is small, and the work memory used for encoding and decoding processing has a memory size of Even small ones are enough. Therefore, it is possible to leave the encoding / decoding process to the semiconductor chip.
Moreover, since the compression rate of traffic information can be changed in units of small blocks, the details of traffic information can be set according to necessity.
In addition, by using the boundary position of the traffic information block, it is possible to correct the shift in the distance direction of the road, and to convey highly accurate traffic information.

(First embodiment)
In the traffic information generation method according to the embodiment of the present invention, as shown in FIG. 34 (b), traffic information positioned at equal intervals along the target road is converted into blocks of a certain distance (that is, a certain number of sampling points). Divide and encode the traffic information in units of this small block. And the road shape data of the object road which specified the division | segmentation section of traffic information, and the traffic information encoded by the small block unit are transmitted to the receiving side. The receiving side individually decodes the traffic information of the small blocks, and connects the obtained traffic information to reproduce the traffic information of the target road.

  In this case, since the number of samples (data amount) included in the small block is the number of samples (data amount) handled collectively when encoding and decoding traffic information, the burden on the program is lightened. The work memory used for encoding and decoding of information is sufficient even if the memory size is small.

FIG. 1 schematically shows a method for generating this traffic information.
FIG. 1A shows a target road of traffic information, and FIG. 1B shows a traveling speed measured by the probe car per unit time, a speed on the vertical axis, and a distance from the base point of the target road on the horizontal axis. It is represented by a graph. This graph is nothing but a graph of the traffic information represented in the form of FIG. 34 (b) even though there is a difference in sampling point intervals. This speed information may be viewed as traffic information sent from the probe car to the center, or may be viewed as traffic information collected by the center from the probe car and provided to a car navigation device or the like.

  In the graph of FIG. 1B, the solid line represents the speed measurement data, the alternate long and short dash line represents the speed information obtained by compressing the measurement data at a low compression rate, and the fine dotted line represents the intermediate measurement data. The speed information compressed by the compression rate is represented, and the rough dotted line represents the speed information obtained by compressing the measurement data at a high compression rate.

  Here, the traffic information is divided in units of 1000 m. A block marker indicating the boundary position of the block of traffic information is set on the target road, and road shape data of the target road is generated so that the position of the block marker can be understood (“setting of block marker”). In FIG. 1A, nodes for obtaining this road shape data are set at intervals of a distance L1 in a tight curve section where the curvature of the target road is large, and in a gentle curve section where the curvature is small. The distance is set at an interval of distance L2 (> L1), and the block marker position is added to the node. Instead of changing the block marker position to a node, identification information of an adjacent node of the block marker and information on the distance to the node may be held.

The traffic information divided into block units is encoded by orthogonal transform in block units (“orthogonal transform coding process”). At this time, the compression rate of the encoded data is set in units of blocks (“setting the compression rate for each block”).
Also, traffic information encoded in units of blocks may be inconsistent (block noise) at block boundaries when the information is decoded and connected to each block. In order to avoid this, processing for reducing block noise is performed in advance (“block noise reduction processing”).
The traffic information encoded in block units is provided together with the road shape data of the target road.

The receiving side that has received such information identifies the target road from the road shape data, and positions the traffic information decoded in units of blocks on the target road. At this time, the positional deviation in the length direction of the target road is corrected using the distance information between the block markers ("distance deviation correction process").
FIG. 2 is a block diagram showing the configuration of the information transmitting apparatus 10 that provides the traffic information generated by this method and the information utilization apparatus 40 that utilizes the provided traffic information. The information transmission device 10 is a probe car on-board device that transmits probe information, or a traffic information center that provides edited traffic information. The information utilization device 40 is a probe information collection center that collects probe information, or a car navigation device that receives traffic information.

  The information transmission device 10 includes a traffic information / measurement information input unit 11 for inputting measurement information and traffic information positioned at equal intervals along the road, and a traffic information block for generating traffic information in block units from the input information. Unit 14, a block-by-block compression rate determination unit 16 that sets a compression rate for each block of traffic information, a block noise reduction processing unit 17 that performs block noise reduction processing, and orthogonal transform coding processing on traffic information in units of blocks. An orthogonal transform coding processing unit 19 to perform, a digital map database (A) 12, a shape data extraction unit 13 for generating road shape data of a target road of a probe car travel locus and traffic information from the input information, a road A block position marker adding unit 15 for adding a block marker to the shape data, and a variable length encoding processing unit 1 for variable length encoding the road shape data. When, and a data transmission unit 20 for transmitting the traffic information and road shape data encoded in block units, and storing the traffic information and road shape data, and a data storage unit 21 provided through the external media.

  On the other hand, the information utilization device 40 includes a data reception unit 41 that receives data transmitted from the information transmission device 10, a shape-encoded data decoding unit 42 that decodes variable-length-encoded road shape data, and a road shape. A shape data restoring unit 43 for restoring data, a digital map database (B) 45, a map matching unit 44 for identifying a road represented by road shape data on the digital map of the digital map database (B) 45, A block position specifying unit 46 for specifying the position of the block marker, a block-specific correction coefficient calculating unit 47 for calculating a correction coefficient used for the distance shift correction processing, and decoding the block-wise traffic information encoded by orthogonal transform A traffic information encoded data decoding unit 48 that performs the block noise reduction processing unit 49 that performs block noise reduction processing of the decoded traffic information. A block-by-block unit distance correction unit 50 that corrects the position of a sampling point in the block, a traffic information superimposition unit 51 that superimposes traffic information on the target road, and an information utilization unit 52 that utilizes the traffic information. Yes.

A traffic information generation method performed by the information transmission apparatus 10 will be described in detail.
<Block marker setting>
When the information transmission device 10 is a probe car on-vehicle device, the traffic information / measurement information input unit 11 measures the coordinates of the sampling points (nodes) and the sampling points as shown in FIG. Measurement information such as measurement time, distance between sampling points, and velocity is input. The traffic information blocking unit 14 generates traffic information in block units from the input information, and the shape data extracting unit 13 selects the coordinates of the sampling points from the input information to generate road shape data of the travel locus. The block position marker adding unit 15 adds block marker information to the road shape data.

This block marker setting process is performed according to the procedure shown in FIG.
A fixed distance (or a fixed number of sampling points) is set in advance as a block marker giving unit. Alternatively, this distance may be dynamically determined according to the amount of free memory that can be used as a work memory for encoding.
The measurement is repeated every unit time (or at constant distance intervals) until the time for transmitting the probe information to the probe information collection center comes, and the measurement data is accumulated in the buffer (step 1). When the probe information transmission time arrives (step 2), the traffic information blocking unit 14 determines a block marker addition unit (step 3), and the measurement information input from the traffic information / measurement information input unit 11 A block marker is set in a given unit, and block marker information shown in FIG. 3B is generated (step 4).

  If a fixed distance (or sampling points) is determined in advance as the block marker assignment unit, the accumulated value (or sampling points) of the inter-node distance data of the input measurement information is the block marker addition unit distance. Each time (or the number of sampling points) is reached, the node number is written in the block marker information. Further, when the distance of the block marker giving unit is dynamically determined according to the free memory amount, the current free memory amount is measured, and the distance (or the number of sampling points) of the block marker giving unit is determined from the value.

  The traffic information blocking unit 14 also extracts measurement data such as the measurement time and the distance and speed between sampling points from the measurement information set with the block marker, and generates measurement information for each block (step 5). . The traffic information blocking unit 14 sends the generated block marker information to the block position marker adding unit 15, and the block position marker adding unit 15 generates the road of the travel locus generated by the shape data extracting unit 13 based on the block marker information. Block marker position information is added to the shape data (step 6).

  When the information transmitting apparatus 10 is a center that provides traffic information, sampling points (as traffic information of a large number of roads are obtained from the traffic information / measurement information input unit 11 as shown in FIG. Node) coordinates, distance between sampling points, and traffic information positioned at the sampling points. The traffic information block forming unit 14 generates traffic information in block units from the input information, and the shape data extracting unit 13 selects the coordinates of the sampling points from the input information, and the road shape data of the target road of the traffic information. The block position marker adding unit 15 adds block marker information to the road shape data.

This block marker setting process is performed according to the procedure shown in FIG. A fixed distance (or a fixed number of sampling points) is set in advance as a block marker giving unit. Alternatively, in an interactive system, this distance may be dynamically determined according to the request of the counterpart device.
When shape data and traffic information (FIG. 5 (a)) are input through the traffic information / measurement information input unit 11 in order from the one with the identification number 1 (steps 10 and 11), the traffic information blocking unit 14 A marker assignment unit is determined (step 12), a block marker is set in the given unit for the input information, and block marker information shown in FIG. 5B is generated (step 13).

  If a fixed distance (or sampling points) is determined in advance as the block marker assignment unit, the accumulated value (or sampling points) of the inter-node distance data of the input measurement information is the block marker addition unit distance. Each time (or the number of sampling points) is reached, the node number is written in the block marker information. In the case of an interactive system, a block marker is set for each distance (or number of sampling points) applied from the counterpart device.

The traffic information blocking unit 14 also extracts each piece of traffic information positioned at the sampling point from the input information set with the block marker in units of blocks, and generates traffic information in units of blocks (step 14). The traffic information blocking unit 14 sends the generated block marker information to the block position marker adding unit 15, and the block position marker adding unit 15 targets the traffic information generated by the shape data extracting unit 13 based on the block marker information. Block marker position information is added to the road shape data of the road (step 15).
Such a process is repeated for all the shape data until the setting of the block marker is completed (steps 16 and 17).

<Compression rate setting for each block>
The block-by-block compression rate determination unit 16 sets the compression rate of the traffic information block generated by the traffic information blocking unit 14 as follows.
(1) When the information transmitting device 10 is a traffic information providing center or a probe car on-vehicle device, when the speed change between blocks is large, detailed information is required, so the compression rate is set small. Specifically, the average speed of each block is calculated, and the compression rate is changed depending on the difference in average speed with adjacent blocks.

(2) When the information transmitting apparatus 10 is a traffic information providing center, if there is an occurrence event such as an accident, construction, or regulation, detailed information is required, so the compression rate is set small. Specifically, the presence / absence of an occurrence event such as an accident, construction, or regulation in each block is determined, and the compression rate is changed depending on the degree of influence of the occurrence event on the traffic flow (number of regulated lanes, etc.).
(3) When the information transmission device 10 is a probe car on-vehicle device, the compression rate is changed depending on whether or not a measurement event has occurred, such as reducing the compression rate when a sudden brake is depressed. Specifically, it is determined whether or not a predetermined event has occurred in each block, and the compression rate is changed depending on the content of the generated event.

(4) When the information transmitting apparatus 10 is a probe car on-vehicle device, the information freshness of the measurement information decreases as the time elapses from the measurement time point, so the compression rate is set higher. Specifically, the time of the last (or first) measurement point of each block is calculated, and the compression rate is changed according to the elapsed time.
(5) When the information transmission device 10 is a probe car on-vehicle device, the compression ratio around the position designated by the information collection center is changed. Specifically, it is determined whether or not a location designated by the information collection center exists in each block. If there is a location, the compression rate of the block is changed to the designated compression rate.

<Orthogonal transform coding process>
Next, an orthogonal transform coding process performed by the orthogonal transform coding processing unit 19 before the block noise reduction process will be described.
Here, a case where discrete wavelet transform (DWT) is used as orthogonal transform will be described.
The DWT can be realized by a filter circuit that recursively divides a low frequency band, and the inverse transformation (IDWT) can be realized by a filter circuit that repeats the reverse synthesis at the time of division. Although various filter configurations may exist in the DWT, an example using a DWT 2 × 2 filter (a filter that generates one wavelet coefficient and one scaling coefficient from two inputs) will be described below. .

  FIG. 7A shows a DWT filter circuit. This DWT circuit is configured by a cascade connection of a plurality of circuits 191, 192, and 193 each including a low-pass filter 181, a high-pass filter 182, and a thinning circuit 183 that thins out a signal to ½. The high-frequency component of the signal input to the circuit 191 passes through the high-pass filter 182, and is then thinned out by the thinning-out circuit 183 and output. The low-frequency component passes through the low-pass filter 181. Thereafter, the data is thinned out by a thinning circuit 183 and input to the next circuit 192. FIG. 8A shows a specific configuration of each circuit 191, 192, 193. “Round” in the figure represents rounding processing.

  When two pieces of data are input to the circuit 191, the data is converted into one high-frequency component data (referred to as wavelet coefficients) and one low-frequency component data (referred to as scaling coefficients). . The scaling coefficient indicates information obtained by smoothing (averaging) input data, and the wavelet coefficient indicates difference information for restoring original data from the scaling coefficient.

Further, when the circuit 191 2 ^two data inputs, are generated and two wavelet coefficients and two scaling factors, the two scaling factors, if you enter the circuit 192, similarly, one A wavelet coefficient and one scaling coefficient are generated. The wavelet coefficients and scaling coefficients generated by the circuit 191 are referred to as primary wavelet coefficients and primary scaling coefficients, respectively. The wavelet coefficients and scaling coefficients generated by the circuit 192 are respectively secondary wavelet coefficients and secondary scaling. It is called a coefficient.

Similarly, if two ^three data are input to the circuit 191, are generated and four primary wavelet coefficients and four primary scaling coefficients, this four primary scaling factor, when the input to the circuit 192 When two second-order wavelet coefficients and two second-order scaling coefficients are generated and these two second-order scaling coefficients are input to the circuit 193, one third-order scaling coefficient and one third-order wavelet are generated. Coefficients are generated.

Thus, in the 2 × 2 filter, the number of input data needs to be a multiple of 2 to the Nth power.
FIG. 7B shows an IDWT filter circuit. The IDWT circuit includes an interpolation circuit 186 that interpolates the signal twice, a low-pass filter 184, a high-pass filter 185, an adder 187 that adds the outputs of the low-pass filter 184 and the high-pass filter 185, and The low-frequency component and high-frequency component signals input to the circuit 194 are interpolated twice, added, and input to the next circuit 195. . FIG. 8B shows a specific configuration of each circuit 194, 195, 196.

Now, when one third-order scaling coefficient generated by the filter circuit of FIG. 7A is input to the circuit 194 as a low-frequency component and one third-order wavelet coefficient is input as a high-frequency component, the circuit 194 The two secondary scaling factors are reproduced. Further, one of the secondary scaling coefficients is input as a low frequency component of the circuit 195, and one secondary wavelet coefficient is input as a high frequency component, thereby reproducing two primary scaling coefficients. Therefore, four primary scaling coefficients can be reproduced by combining two secondary scaling coefficients and two wavelet coefficients. Similarly, the circuit 196 can reproduce 23 ³ input data by combining the four primary scaling coefficients reproduced by the circuit 195 and the four primary wavelet coefficients.
That is, one third-order scaling coefficient, one third-order wavelet coefficient, two second-order wavelet coefficients, and four first-order wavelets converted from eight input data by the filter circuit of FIG. Eight input data can be reproduced using the coefficients.

  It should be noted here that even if there are no four primary wavelet coefficients, four primary scaling coefficients can be reproduced, and the state of eight input data can be known with coarse resolution by this scaling coefficient. It is a point that can be. Also, even from only one third-order scaling coefficient and one third-order wavelet coefficient, two second-order scaling coefficients can be reproduced, and this scaling coefficient can be used to change the state of input data to a coarser resolution. You can find out at

  In FIG. 1B, the graph displayed as high compression is a graph showing the transition of speed using a low-order scaling coefficient obtained by DWT conversion of the speed data, and is also displayed as medium compression. Is a medium order scaling factor, and the graph displayed as low compression represents the transition of speed using a high order scaling factor.

The flowchart of FIG. 9 shows the DWT for the traffic information in units of blocks and the pre-processing and post-processing procedures. The processing from step 20 to step 28 shows pre-processing until the input data of multiples of 2 N is prepared from the traffic information in block units, and the traffic information in block units is converted into position resolution (distance resolution). Are sampled at intervals corresponding to, and rounded according to the expression resolution to generate input data that is an integer multiple of 2 ^N. If the number of input data does not match an integer multiple of 2 ^N , 0 or the last numerical value is added as a dummy so as to match.

  Next, in order to reduce the absolute value of the input data, the level of each data is shifted by the intermediate value of the input data (step 29), and the order N of the DWT is determined (step 30). This corresponds to determining how many of the cascade-connected filter circuits in FIG. 7A are used to perform DWT.

Next, (step 30) in order from the case of the first 0-order (n = 0), the number of data / 2 ⁿ determines the number of input data (step 32), by applying the DWT to the input data, the scaling factor input data And wavelet coefficients (step 33). At this time, the numbers of data of the scaling coefficient and the wavelet coefficient are each ½ of the number of input data.
The obtained scaling coefficient is stored in the front of the data, and the wavelet coefficient is stored in the back of the data (step 34). If n <N (step 35), the process returns to step 32, the order is incremented by 1, and the number of input data is determined by the number of data / ²ⁿ . At this time, only the scaling coefficient stored forward in step 34 becomes the next input data.

Steps 32 to 34 are repeated until n = N. In this process, when the number of input data is 2 ^N , the scaling coefficient is one. When the number of input data is m × 2 ^N , the scaling coefficient is m.
Next, the data generated by DWT is decomposed into bit planes (step 36), and the binarized bit data is arithmetically encoded (step 37).

FIG. 10 shows a block of traffic information input data (a) adjusted to Na (= 2 ^N ) by adding a dummy to Nb valid data and this input data is generated by applying an Nth-order DWT. The scaled coefficient and wavelet coefficient (b), and the result (c) obtained by bit-plane decomposition of the scaled coefficient and wavelet coefficient are shown. This bit-plane decomposed data is more important as it goes up (ie, the order becomes higher) and becomes more important as it goes to the left side (ie, the higher digit). Therefore, as shown in FIG. 11, if the nth-order bit plane data excluding the lower L digit is sent to the receiving side, the essence of the traffic information can be transmitted, and the receiving side is sufficient to know the traffic situation. Coarse resolution traffic information can be reproduced.

  FIG. 12 shows transmission data (b) in which one block of traffic information is represented by a DWT coefficient, and parameter information (a) thereof. The parameter information (a) includes the length of the corresponding block, the number of data Na (number of divisions of the corresponding block), the number of valid data Nb, the final DWT order N, and the DWT transmission order n indicating the DWT minimum order included in the transmission data. And level shift L indicating the number of digits removed by the transmission data. The transmission data (b) includes an Nth-order scaling coefficient from which the lower L digits are removed and wavelet coefficients from the Nth order to the nth order. By changing the values of Na, N, n, and L in units of blocks, the compression rate in units of blocks can be changed. The compression rate set in <Compression rate setting for each block> It can be realized by changing. It should be noted that the program processing becomes easier when Na of all blocks is aligned.

<Block noise reduction processing>
The block noise reduction processing unit 17 reduces block noise by the following methods (1), (2), and (3).
(1) The block boundary value is stretched as it is, and is compressed and encoded somewhat including the outside of the boundary (referred to as “boundary value stretching method”). When restoring, information outside the block boundary is discarded.
(2) Encoding and compressing data including data slightly deviating from the original block boundary (referred to as “outer boundary encoding method”). When restoring, information outside the block boundary is discarded.
(3) Define a window function that attenuates at both ends, and perform coding so that adjacent blocks overlap (referred to as “window function use method”).
These methods need to encode a wider range than the original range, which leads to an increase in the amount of data, but is a necessary process for reducing block noise.

Next, each method will be described in detail.
(1) Boundary value enlargement method In the boundary value enlargement method, as shown in FIG. 13, a range of traffic information (dotted line range) that samples input data for generating transmission data (encoded data) of the target block K , Hereinafter referred to as “encoding traffic information range”) is extended to the outside of the range of the target block K, and the value of the traffic information in the upstream extended range becomes the value at the boundary on the upstream side of the target block K. The traffic information value in the downstream extended range is set to the value at the downstream boundary of the target block K.

The flowchart of FIG. 14 shows the encoding procedure in this method. First, the number M of blocks of traffic information to be provided is acquired (step 40), the block number K = 1 in order (step 41), the traffic information of block K is acquired (step 42), and both ends of the block K are acquired. As the value of the traffic information in the extended range generated outside the block (step 43), the traffic information in the encoding traffic information range including this extended range is described in <Orthogonal Transform Coding Process>. The orthogonal transformation is performed (step 44). This process is repeated for all blocks of traffic information (steps 45 and 46).
As shown in FIG. 15, the parameter information of the DWT data generated in this way is added with the data number Ma in the upstream extension range and the data number Mb in the downstream extension range.

(2) Out-of-boundary coding method In the out-of-boundary coding method, as shown in FIG. 16, the traffic information range for coding of the target block K (the range of the dotted line) is extended outside the range of the target block K. The traffic information of the adjacent block that falls within the extended range is used as the traffic information of the encoding traffic information range of the target block K.
The flowchart of FIG. 17 shows an encoding procedure in this method. First, the number M of blocks of traffic information to be provided is acquired (step 50), and the traffic information of block K and the extended range traffic information of adjacent blocks are acquired in order from the block of block number K = 1 (step 51). Then (step 52), orthogonal transform is performed on the traffic information in the encoding traffic information range including the extended range (step 53). This process is repeated for all blocks of traffic information (steps 54 and 55).
As in the case of the boundary value enlargement method (FIG. 15), the upstream extension range data number Ma and the downstream extension range data number Mb are added to the parameter information of the DWT data generated in this way.

(3) Window Function Usage Method As shown in FIG. 18B, the window function is a function in which the added value with the adjacent window function is always 1, the maximum value is 1 and the minimum value is 0 and both ends are attenuated. It is. Here, the window function f (k) of the target block K intersects the window function f (k-1) of the upstream adjacent block K-1 on the upstream boundary of the target block K, and is downstream of the target block K. The window function f (k) that intersects the window function f (k + 1) of the downstream adjacent block K + 1 on the side boundary is used, and the traffic information in the encoding traffic information range of the target block K is the upstream adjacent block K. −1, the traffic information of the target block K and the downstream adjacent block K + 1 is multiplied by the window function fk.

  The flowchart of FIG. 19 shows an encoding procedure in this method. First, the number of blocks M of the traffic information to be provided is acquired (step 60), the block number K = 1 in order (block 61), and the traffic information of block K and the necessary traffic information of adjacent blocks are acquired. (Step 62), the traffic information value at each sampling point of the traffic information is multiplied by a window function (Step 63), and orthogonal transformation is performed using the traffic information as traffic information in the encoding traffic information range (Step 64). . This process is repeated for all blocks of traffic information (steps 65 and 66).

  As shown in FIG. 20, the window function definition used to generate the traffic information in the encoding traffic information range is added to the parameter information of the DWT data generated in this way. Various types of window functions such as trapezoidal window, triangular window, and trigonometric function window can be used, and the identification information of the used window function is described in the parameter information from several predefined window functions. .

  Thus, the block noise reduction processing is performed, and the traffic information of each block subjected to orthogonal transform coding is sent to the data transmission unit 18 together with the road shape data. The road shape data may be variable length encoded by the variable length encoding processing unit 18 in order to compress the data amount. This variable length coding method is described in detail in the above-mentioned Patent Document 2.

  The data transmission unit 18 transmits the traffic information and road shape data to the information utilization device 40. FIG. 21 shows a data structure of road shape data (a), block marker information (b), and traffic information (c) transmitted to the information utilization device 40. The block marker information (b) includes the shape identification number of the target road included in the road shape data (a), the number of traffic information blocks of the target road, the node number of the node where the block marker is set, the block marker The distance between and is included. The traffic information (c) includes a shape identification number, an information type of traffic information, the number of traffic information blocks, parameter information of each block shown in FIGS. 12 (a), 15 and 20, and FIG. The traffic information of each orthogonally transformed block shown in (b) is included.

In addition, when variable length coding is performed on road shape data, the block marker position is not added to the node, but is set by equidistant resampling (however, the resampling length of the section changes depending on the curvature of the road section). Data compression is more effective when encoded using only nodes. Therefore, in this case, as shown in FIG. 22, the block marker position is represented by distances D1, D2, and D3 from the left adjacent node set by equidistant resampling. The number of bits necessary for displaying D1, D2, and D3 is d (m), which is the resolution necessary to specify D1, D2, and D3.
Number of required bits = roundup [log ₂ (L / d)]
L: Resample length (m)
If d = 3m (the distance that the vehicle travels in about 0.1 second), if L is 10m, 2 bits are enough, and if L is 160m, 6 bits are needed. , L is 640 m, 8 bits are required. FIG. 23 shows the relationship between the resample length and the number of bits necessary for displaying the distance between the node and the block marker. FIG. 24 shows road shape data including the block marker identification code and the distance information (D value) from the node following the node position information.

The information utilization device 40 that has received the traffic information and the road shape data sends the road shape data and the block marker information to the shape encoded data decoding unit 42 and sends the traffic information to the traffic information encoded data decoding unit 48.
The traffic information encoded data decoding unit 48 acquires the orthogonal transform coefficient of each block, and decodes the traffic information in units of blocks in the procedure shown in FIG.

The DWT order N is read from the parameter information of the received traffic information (step 70), n is set to N-1 (step 71), and the number of input data is determined by the number of data / ²ⁿ (step 72). Next, IDWT is performed by the filter circuit of FIG. 8B with the front of the input data as the scaling coefficient and the rear of the input data as the wavelet coefficient to reconstruct the first-order lower-order scaling coefficient (step 73).

If n> 0 or within the time limit, the process returns to step 72, 1 is subtracted from n, and the procedure of steps 72 and 73 is repeated (step 74). When n = 0 and IDWT is completed, the data is reverse-shifted by the amount shifted by the transmission side to restore the traffic information in units of blocks (step 77). When the time limit of IDWT processing has passed, IDWT is terminated and the time resolution is set to 2 ⁿ times to display traffic information with a reduced resolution using the obtained traffic information data (step 76). ), Reverse shift is performed to restore the averaged block-by-block traffic information (step 77).

  The block noise reduction processing unit 49 extracts only the information of the range of the target block K from the restoration value when block noise reduction processing of the boundary value enlargement method or the out-of-boundary encoding method is performed on the transmission side. Thus, traffic information of each block is obtained. When block noise reduction processing using the window function method is performed on the transmission side, the restored value of the target block K is added to the value of the block (K-1) restored before the target block K, and this By repeating the process, traffic information of each block is obtained.

On the other hand, if the road shape data is variable-length encoded, it is decoded by the shape encoded data decoding unit 42 and restored by the shape data restoring unit 43.
The map matching unit 44 specifies the target road represented by the road shape data on the map of the digital map database (B) 45 by performing map matching.

<Distance deviation correction processing>
The blocking position specifying unit 46 calculates the latitude / longitude of the block marker position from the position of each node matched on the target road and the block marker information, and specifies the block section. FIG. 26 schematically shows this processing. FIG. 26A shows road shape data generated by the information transmitting apparatus 10 using the map data of the digital map database (A) 12 (here, the block marker positions (BM1, BM2, BM3) are shown. Set as a node). FIG. 26B shows a state in which the information utilization device 40 represents the node position included in the road shape data on the map of the digital map database (B) 45. The map matching unit 44 positions these nodes on the road of the digital map database (B) 45 by map matching as shown in FIG. The block position specifying unit 46 calculates the latitude and longitude of the block marker positions (BM1, BM2, BM3) positioned on the road from the data of the digital map database (B) 45, and specifies the block section.

  The block-by-block correction coefficient calculation unit 47 calculates the distance (Bd) along the road of each block using the data of the digital map database (B) 45, and the distance (Bd) and the corresponding information represented by the block marker information. From the ratio of the block to the distance between the block markers, the correction coefficient for this block is calculated. When the distance transmitted from the information transmitting apparatus 10 is applied to the block, it is necessary to correct the distance with this correction coefficient.

  The unit distance correction unit 50 for each block corrects the length of the corresponding block included in the parameter information by the correction coefficient, and divides the corrected length by the number of data Na (number of divisions of the corresponding block) for each sample. The distance between the sampling points is obtained, and the position of each sampling point included in the block whose position is specified by the blocking position specifying unit 46 is specified. Then, the traffic information data of this block is assigned to each sampling point to reproduce the traffic information.

  As shown in FIG. 22, when the block marker does not coincide with the node, the distance N1 from the node n1 to the node n2 using the distance between the block markers and the distances D1 and D2 included in the block marker information. Further, the distance N2 along the road from the node n1 to the node n2 matched with the road in the digital map database (B) 45 is obtained, and the correction coefficient is calculated from the ratio of N2 and N1. Then, D1 and D2 are corrected with the correction coefficient, and the block is specified with the point separated by D1 corrected from the node n1 as one boundary and the point separated by D2 corrected from the node n2 as the other boundary.

Further, the unit-by-block unit distance correction unit 50 corrects the distance by the correction coefficient when the accident occurrence position is transmitted by the distance from the reference node, and is matched on the road of the digital map database (B) 45. A point away from the reference node by the corrected distance is specified as the accident occurrence point.
The traffic information superimposing unit 51 sequentially superimposes the restored block-unit traffic information on the target road, and the information utilization unit 52 utilizes the traffic information.
Thus, in this traffic information generation method, the traffic information of the target road is divided into small blocks and encoded, so the burden on the program is small and the work memory used for encoding and decoding processing The memory size can be small. Therefore, the encoding / decoding unit can be configured with a semiconductor chip or the like.

Moreover, since the compression rate of traffic information can be changed in units of small blocks, the details of traffic information can be set according to necessity.
In addition, by using the boundary position of the block of traffic information, it is possible to correct a shift in the distance direction of the road, and to convey highly accurate information.
Further, traffic information in units of small blocks can be efficiently encoded and decoded by a streaming process or pipeline process in which an input block is processed and output before the next block is input.
In addition, sampling of traffic information and block division may be performed after the sampling is performed, and the obtained sampling data may be divided into a plurality of blocks. Sampling may be performed at predetermined intervals in each block.

<Modification>
So far, the case where the length of each block is set constant has been described, but the block of traffic information may be divided at a point where the traffic flow is likely to change (such as a bottleneck intersection or in front of a famous facility). FIG. 27 shows an example in which block markers are set at famous intersections and bottleneck intersections. In this case, the distance between the block markers is unequal, but the number of data Na is set by making the number of divisions (data number Na) in each block constant or within a range not exceeding a predetermined maximum value. By setting, it is possible to reduce the burden of encoding / decoding processing, adaptively change the compression rate, and effect of distance direction deviation correction. In the case of this modification, the traffic situation between important intersections is represented by traffic information of one block, so that it becomes easier to understand. In addition, the information utilization device can select a block for reproducing traffic information and reproduce only the traffic situation between intersections to be known.

  So far, the case where traffic information is divided into blocks by distance has been described. However, when the on-vehicle probe car provides traffic information (measurement information) to the probe information collection center, the traffic information is converted to time. You may make it transmit by dividing | segmenting by a unit. When the center provides travel time traffic information, the traffic information can be blocked in units of travel time.

  So far, the case where road shape data including a data string of node positions on the target road is used to convey the target road of the traffic information has been described. However, data (road section) for specifying the target road has been described. As the reference data, for example, an identification code attached to the target road section in advance, a road section identifier (link number) or an intersection identifier (node number) determined in a unified manner may be used.

Further, when both the providing side and the receiving side refer to the same map, the providing side can transmit latitude / longitude data to the receiving side, and the receiving side can specify a road section by this data.
In addition, the road map is identified by using the identifiers attached to each of the road maps divided into tiles, the kilometer posts, road names, addresses, and postal codes provided on the roads as road section reference data. May be.

(Second Embodiment)
In the second embodiment, an example in which block markers are arbitrarily set at unequal intervals as in the modification of FIG. This second embodiment is an example suitable for a case where a probe car is assumed as the information transmitting apparatus and traffic information such as speed information is collected by the probe car.

  FIG. 28 is a diagram schematically illustrating a first example and a second example of a traffic information generation method according to the second embodiment. The first example is a case where the traveling direction of the probe car changes greatly by a predetermined value or more based on the output of a vehicle sensor such as a steering wheel steering angle sensor or a gyro provided in the probe car, that is, when the vehicle is bent by a predetermined angle or more during traveling. It is determined that an event has occurred, and a block marker is set at this location. Consider a case where there is an intersection at a point 3000 m to 4000 m from the block marker setting start point as shown in FIG. 28 and the probe car turns right here. It is assumed that there is a traffic jam waiting for a right turn before this intersection.

  A place where such a probe car bends greatly is considered to be a change point of traffic conditions such as an intersection, so by inserting a block marker here, the traffic situation can be reduced even if the traffic information is compressed in blocks. It is possible to clearly determine the changing position. In addition, the block marker clearly indicates where the traffic situation changes such as an intersection, so when calculating the right / left turn waiting time (right / left turn cost) from the collected traffic information, the position of the intersection is clearly grasped. This can improve the accuracy of the waiting time for turning left and right. Also, when generating traffic jam information, it is possible to easily determine the position of a queue break such as a traffic jam start position or an end position, and it becomes easy to calculate a waiting time or a queue end position.

  The second example is another example in which the output of the vehicle sensor is used, and an event occurs when the probe car has been stopped for N minutes or more based on the output of a vehicle sensor such as a speed sensor provided in the probe car. It is determined and a block marker is set at this place. For example, a block marker is inserted when the stop state continues for 3 minutes or more. Usually, the signal control cycle is 45 to 180 seconds, and the stop for waiting for the signal is about 20 to 90 seconds. Even if it does not move at all for two cycles, such as when the intersection is clogged, the maximum stop time is about 180 seconds. If it has stopped for longer than this time, it is considered that the car is not in a traffic flow, such as getting on and off a taxi or waiting for a person. Since such a stop is not appropriate as traffic information, a block marker is inserted to clearly indicate the stop event occurrence location. Thereby, it is possible to clearly determine the position where the traveling state of the probe car has changed, and to provide highly accurate traffic information.

  In the first example and the second example described above, by changing the compression rate of the traffic information in the blocks before and after the block marker set at the event occurrence point such as a right turn or stop at the intersection, an appropriate amount of information is obtained for each divided block. It is possible to generate traffic information. For example, lowering the compression rate of the upstream block located before the intersection to increase the amount of information and further refine the traffic information to make it easier to grasp the end of the queue such as traffic congestion waiting for a right turn Can do.

  FIG. 29 is a diagram schematically illustrating a third example and a fourth example of the traffic information generation method according to the second embodiment. The third example is based on the map information of the navigation device provided in the probe car and the own vehicle position, the location where the probe car has left the road, the location of the specific object that is of interest to users such as parking lots, stores, play facilities, etc. It is determined that an event has occurred at a POI (Point Of Interest) entrance point, a private road or a point entering a facility road, and a block marker is set at this location.

  When a car enters POI, it will leave the public road network, or drive on a private road or facility road. Normally, traffic information such as traffic jam information does not require information other than the public road network, so the boundary points between the public road network and others are clearly indicated by inserting block markers at each of the above points. This makes it possible to easily identify entry / exit positions other than the public road network, and to provide highly necessary traffic information. Also, when there is a traffic jam waiting for entry to a parking lot or facility, when generating traffic jam information, as in the first example above, the position of the queue break such as the traffic jam start position and end position is set. It can be easily discriminated and it becomes easy to calculate the waiting time and the end position of the queue.

  In the fourth example, it is determined that an event has occurred at the time of communication based on information of a communication device such as a DSRC (Dedicated Short Range Communication) type narrow-range wireless communication device provided in the probe car. It is to set. For example, data transmission / reception occurs at the gate of an ETC (Electronic Toll Collection) system using DSRC narrow-area communication provided at tollgates on expressways, and at the DSRC system provided at the entrance of a parking lot or facility Insert a block marker at times.

  Due to traffic jams at toll booths, traffic conditions also change before and after the toll booth and at interchange entrances and exits connected to the toll booth. In addition, traffic conditions may change at parking lots and entrances to facilities due to traffic congestion waiting to enter. By inserting a block marker at such a point, it is possible to clearly determine the position where the traffic situation changes. In addition, it is possible to clearly discriminate the entry point of POI, etc., and to clearly distinguish the public road network from other places in the POI, etc., and to provide useful traffic information.

  FIG. 30 is a block diagram illustrating a configuration of an information transmission device 110 that provides traffic information and an information utilization device 40 that utilizes the provided traffic information in the second embodiment. This information transmission device 110 is a probe car on-vehicle device, and is a partial modification of the configuration of the information transmission device 10 of the first embodiment shown in FIG. In FIG. 30, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The information transmission device 110 includes a GPS position detection unit 121, a speed sensor 122, and a gyro 123 as vehicle sensors. Also, a travel locus measurement information input unit 111 that captures the map information of the digital map database (A) 12 and the measurement information from each vehicle sensor and inputs it as travel locus measurement information of the probe car, and a travel locus measurement information input unit 111. A travel trajectory shape extraction unit 113 for generating the travel trajectory shape data of the probe car related to the target road and POI of the traffic information from the output information, the travel trajectory measurement information input unit 111, the digital map database (A) 12, and each vehicle A measurement information blocking determination unit 114 that determines a division position of measurement information to be blocked from output information of the sensor and generates traffic information in units of blocks, a travel locus shape extraction unit 113, and a measurement information block determination determination unit 114 Add block marker to shape data of running track from output information. And a section 115. In addition, information from the steering angle sensor 124 and the DSRC communication unit 125 is input to the measurement information blocking determination unit 114.

  The block marker setting process in the information transmitting apparatus 110 configured as described above is performed according to the procedure shown in FIG. FIG. 31 is a flowchart showing a procedure for giving a block marker to probe car measurement information in the second embodiment.

  The measurement of the speed and the like by the probe car is repeated every unit time (or at regular distance intervals), and the measurement data is accumulated in the buffer (step 101). When the probe information transmission time comes (step 102), the measurement information blocking determination unit 114 determines a block marker addition unit (step 103). Here, the unit for giving the block marker is a value fixedly determined in the system or a value determined by measuring the amount of free memory in the current buffer. Two types of fixed distance units and fixed time units are conceivable. First, the node number N = 1 of the road shape data of the target road is set (step 104), the travel locus measurement information input unit 111, the digital map database (A) 12, the GPS position detection unit 121, the speed sensor 122, and the gyroscope 123. The information from each vehicle sensor is input, and it is determined whether or not a predetermined event has occurred in the node N (step 105).

  Here, as described in the first to fourth examples above, as the predetermined event, (1) “turned at a large angle” from the output of the vehicle sensor (steering wheel steering angle, gyroscope, GPS bearing, etc.) When it is determined, (2) When it is determined from the output (speed etc.) of the vehicle sensor that “the vehicle has been stopped for a predetermined time or more”, (3) From the map matching result of the shape data of the travel locus, (4) If it is determined that it is “POI (parking lot etc.) entrance”, “I entered a private road or in-facility road”, or it is determined to be a key traffic point in front of a major intersection or large-scale facility When communication with the ETC system or the DSRC system occurs based on information from the DSRC communication unit.

  When a predetermined event occurs (Yes in Step 106), the measurement information blocking determination unit 114 sets a block marker at a location where this event has occurred, and generates block marker information (Step 107). Then, it is determined whether the distance or time interval from the previous marker setting position exceeds the determined grant unit (step 108). On the other hand, if no event has occurred in step 106, the giving unit determination in step 108 is performed without generating the block marker in step 107. If it exceeds the grant unit (Yes in step 109), block marker information in a fixed grant unit is generated (step 110). Thereafter, it is determined whether the processing has been completed for all nodes of the road shape data of the target road (step 111). On the other hand, if the given unit is not exceeded, block node generation in step 110 is not performed, and all node end determination is performed in step 111.

  If the block marker insertion determination and generation processing has not been completed for all nodes of the road shape data of the target road, the node number is incremented by 1 as N = N + 1 (step 112), and the process returns to step 105 for the next node. Similarly, the processes in steps 105 to 110 are repeated. On the other hand, when the processing of all nodes is completed, the compression rate of traffic information is determined by the block-by-block compression rate determination unit 16 for each block divided by the block marker generated by the measurement information blocking determination unit 114, After the block noise reduction processing unit 17 performs block noise reduction processing, the orthogonal transform coding processing unit 19 performs orthogonal transform coding processing such as DWT on a block basis to compress the data (step 113). Further, the block position marker adding unit 115 adds the position information of the block marker to the shape data of the traveling locus generated by the traveling locus shape extracting unit 113 based on the block marker information generated by the measurement information blocking determination unit 114. (Step 114).

  When traffic information is divided into small blocks and compressed in units of blocks, measurement information such as speed and unit section travel time is averaged along with the compression, so increasing the compression rate makes it difficult to determine changes in traffic conditions. Therefore, when generating traffic information or the like, it may be difficult to determine the end position of the event. Therefore, in the second embodiment, when an event corresponding to a traffic situation change point such as an intersection turn left or right or POI entrance occurs, a block marker is set at this corresponding position, thereby easily changing the traffic situation change point. It becomes possible to discriminate. Moreover, in each block divided | segmented by this block marker, appropriate efficient compression processing can be performed, and the reduction of the data amount of traffic information and the improvement of usefulness can be made compatible.

The traffic information generation method of the present invention can reduce the burden of software and hardware on the side that generates traffic information and the side that uses traffic information, and can be used for transmission and recording. It can be widely used when generating probe information and the like.
The device of the present invention can be applied to a center device of a traffic information providing system, a probe car on-vehicle device that provides measurement information, and the like, and a center device for collecting probe car information as a device that uses information. It can also be widely applied to information terminals such as car navigation devices, personal computers, PDCs, and mobile phones.

Schematic diagram illustrating a method for generating traffic information in the first embodiment of the present invention The block diagram which shows the structure of the information transmitter in the 1st Embodiment of this invention, and an information utilization apparatus. The figure which shows the driving | running locus | trajectory and measurement data of a probe car, and block marker information in embodiment of this invention The flowchart which shows the block marker provision procedure to the probe car measurement information in the 1st Embodiment of this invention The figure which shows road shape data and traffic information, and block marker information in embodiment of this invention The flowchart which shows the block marker provision procedure to the road shape data and traffic information in the 1st Embodiment of this invention (A) DWT filter circuit (b) IDWT filter circuit (A) Lifting configuration of DWT filter circuit (b) Lifting configuration of IDWT filter circuit FIG. 3 is a flowchart showing a procedure of orthogonal transform encoding processing in the embodiment of the present invention. Diagram showing changes in data by DWT Diagram explaining the transmission data part The figure which shows the parameter information and traffic information which were produced | generated by the method in embodiment of this invention The figure explaining the boundary value enlargement method used with the block noise reduction method in the embodiment of the present invention The flowchart which shows the procedure of the boundary value enlargement method in embodiment of this invention The figure which shows the parameter information produced | generated by the boundary value enlargement method in embodiment of this invention The figure explaining the outer boundary encoding method used with the block noise reduction method in embodiment of this invention The flowchart which shows the procedure of the outer boundary encoding system in embodiment of this invention The figure explaining the window function usage system used with the block noise reduction method in the embodiment of the present invention The flowchart which shows the procedure of the window function usage system in embodiment of this invention The figure which shows the parameter information produced | generated by the window function usage system in embodiment of this invention The figure which shows the data structure of the road shape data produced | generated by the traffic information production | generation method in the embodiment of this invention, block marker information, and traffic information. The figure explaining the other block marker setting method in the production | generation method of the traffic information in embodiment of this invention Diagram showing the relationship between the resample length and the number of bits required to display the distance between the node and block marker The figure which shows the other data structure of the road shape data produced | generated with the production | generation method of the traffic information in embodiment of this invention Flow chart showing the processing procedure of IDWT The figure explaining the distance shift correction method in embodiment of this invention The schematic diagram which shows the modification of the generation method of the traffic information in embodiment of this invention The schematic diagram explaining the 1st example and 2nd example of the production | generation method of the traffic information in the 2nd Embodiment of this invention The schematic diagram explaining the 3rd example and the 4th example of the production | generation method of the traffic information in the 2nd Embodiment of this invention The block diagram which shows the structure of the information transmitter in the 2nd Embodiment of this invention, and an information utilization apparatus. The flowchart which shows the block marker provision procedure to the probe car measurement information in the 2nd Embodiment of this invention Diagram explaining road shape data A diagram explaining the position resolution and expression resolution of traffic information Diagram explaining how to express traffic information as a function of road

Explanation of symbols

10, 110 Information transmitter 11 Traffic information / measurement information input unit 12 Digital map database (A)
DESCRIPTION OF SYMBOLS 13 Shape data extraction part 14 Traffic information block formation part 15, 115 Block position marker addition part 16 Compression ratio determination part for every block 17 Block noise reduction process part 18 Variable length encoding process part 19 Orthogonal transform encoding process part 20 Data transmission part DESCRIPTION OF SYMBOLS 21 Data storage part 40 Information utilization apparatus 41 Data receiving part 42 Shape encoding data decoding part 43 Shape data decompression | restoration part 44 Map matching part 45 Digital map database (B)
46 Block position specifying unit 47 Correction coefficient calculation unit for each block 48 Traffic information encoded data decoding unit 49 Block noise reduction processing unit 50 Unit distance correction unit for each block 51 Traffic information superposition unit 52 Information utilization unit 111 Traveling track measurement information input unit 113 Traveling track shape extraction unit 114 Measurement information block determination unit 121 GPS position detection unit 122 Speed sensor 123 Gyro 124 Steering angle sensor 125 DSRC communication unit 181 Low-pass filter 182 High-pass filter 183 Thinning-out circuit 184 Low-pass filter 185 High-pass filter 186 Decimation circuit 187 Addition circuit 191 Filter circuit 192 Filter circuit 193 Filter circuit 194 Filter circuit 195 Filter circuit 196 Filter circuit

Claims (35)

A traffic information generation method for sampling traffic conditions of a target road at predetermined intervals along a road, and dividing an array of sampled data into a plurality of blocks so that a plurality of sampled data are included in one block. A method of generating traffic information, characterized in that encoding is performed by orthogonal transform in units of the block for the plurality of sampled data included in the block. 2. The traffic information generating method according to claim 1, wherein the number of the plurality of sampled data included in each of the blocks is set to a predetermined upper limit number or less. The traffic information generation method according to claim 2, wherein the number of the plurality of sampled data included in each of the blocks is set to be constant.   4. The traffic information generating method according to claim 1, wherein the target road is divided at a constant distance interval, and the block is generated corresponding to the divided section.   The traffic according to any one of claims 1 to 3, wherein the target road is divided at unequal distance intervals with a selected point as a boundary, and the block is generated corresponding to the divided section. How information is generated.   6. The traffic information generation method according to claim 5, wherein an intersection or a facility point is selected as the boundary.   4. The traffic information generation method according to claim 1, wherein the block is generated by dividing the sampled data into time units.   When the sampling data is measurement information measured by a probe car vehicle-mounted device, the measurement information is divided into a plurality of times according to a time zone of measurement time, and the block is generated by the divided measurement information. The method for generating traffic information according to any one of claims 1 to 3.   When the sampling data is measurement information measured by a probe car on-vehicle device, travel information on the probe car on-vehicle device, position information on map information in which the position of the probe car on-vehicle device is associated, the probe The block marker which shows the boundary of the said block is set based on at least any one of the communication operation information in the communication part mounted in the car vehicle equipment, The Claim 1 characterized by the above-mentioned. How to generate traffic information.   The block marker is set when a predetermined event occurs in the traveling of the probe car on-vehicle device based on at least one of the traveling information, the position information, and the communication operation information. The traffic information generation method described in 1.   The method for generating traffic information according to any one of claims 1 to 10, wherein a data compression rate in encoding is set for each block. 12. The traffic information generation method according to claim 11, wherein the data compression rate is changed according to an average speed of the block represented by the plurality of sampled data. 12. The traffic information generation method according to claim 11, wherein the data compression rate is changed according to a change rate between blocks of an average speed of the blocks represented by the plurality of sampled data.   The traffic information generation method according to claim 11, wherein the data compression rate is changed according to an event occurring in a section corresponding to the block. 12. The traffic information generation method according to claim 11, wherein the data compression rate of a block including measurement information of the probe car on-board device as sampling data is changed according to an event measured by the probe car on-board equipment.   The traffic information generation method according to claim 11, wherein the data compression rate of the block including the measurement information as sampling data is changed according to the measurement time of the measurement information measured by the probe car onboard device.   12. The traffic information according to claim 11, wherein the data compression rate of the block including the measurement information measured by the probe car vehicle-mounted device is changed depending on whether or not the measurement point is around a specified position. Generation method. 2. The coding according to claim 1, wherein, when coding in units of blocks, the range of the block is expanded and coding is performed on a plurality of sampled data of the block including sampled data of an extended portion. Traffic information generation method.   19. The traffic information generation method according to claim 18, wherein the value of the sampled data in the extended portion is matched with the value of the sampled data at the original boundary of the block.   19. The traffic information generation method according to claim 18, wherein the value of the sampled data of the extension portion is matched with the value of the sampled data corresponding to a block adjacent to the block.   The value of the sampled data of the extension part is matched with the value of the corresponding sampled data of the block adjacent to the block, and the sampled data of the block including the extension part is multiplied by a window function 19. The traffic information generation method according to claim 18, wherein the value is sampled data of the block.   The traffic information generation method according to claim 1, wherein position information indicating a boundary of the block is added to road reference data for specifying the target road to form a part of the traffic information. A method of reproducing traffic information in which traffic conditions of a target road are sampled along a road at predetermined intervals, and the array of sampled data is divided into a plurality of blocks so that a plurality of sampled data is included in one block. A traffic information reproducing method comprising: obtaining traffic information generated by encoding in units of blocks, decoding the traffic information in units of blocks, and reproducing sampled data.   The traffic information reproducing method according to claim 23, wherein in reproducing the sampled data, the traffic information is output in association with position information.   24. The traffic information reproducing method according to claim 23, wherein in reproducing the sampled data, the traffic information is displayed on display means in association with position information.   The program for making a computer perform each procedure of the production | generation method of the traffic information in any one of Claims 1-22.   The program for making a computer perform each procedure of the reproduction | regeneration method of the traffic information in any one of Claims 23-25. A traffic information generation device that samples traffic conditions of a target road at predetermined intervals along the road,
Block dividing means for dividing an array of sampled data corresponding to the traffic situation into a plurality of blocks so that a plurality of sampled data is included in one block;
Encoding means for performing encoding by orthogonal transform in units of the block for the plurality of sampled data included in the block;
A traffic information generating apparatus comprising: Traffic information blocking means for dividing an array of sampled data obtained by sampling the traffic situation of the target road into a plurality of blocks so that a plurality of sampled data are included in one block;
A block-by-block compression rate determining means for determining a compression rate in encoding of the plurality of sampled data included in the block;
Block noise reduction processing means for performing processing for reducing block noise generated at the boundary of the block at the time of decoding;
An orthogonal transform coding processing means for performing orthogonal transform coding on a block basis for the plurality of sampled data of the block subjected to block noise reduction processing; Generator.   A block position marker adding means for adding position information of a block marker indicating a boundary of the block to road reference data for specifying the target road; the encoded data generated by the orthogonal transform encoding processing means; and the block 30. The traffic information generating device according to claim 29, wherein the road reference data to which marker position information is added is provided.   31. The traffic information generating apparatus according to claim 30, wherein the block position marker adding unit divides the target road at a predetermined distance interval and sets the block marker corresponding to the divided section.   The block position marker adding means divides the measurement information at a predetermined time interval when the sampling data is measurement information measured by a probe car onboard device, and associates the block marker with the divided measurement information. The traffic information generating device according to claim 30, wherein:   When the sampling data is measurement information measured by the probe car on-vehicle device, the block position marker adding means is map information in which travel information on the probe car on-vehicle device and the position of the probe car on-vehicle device are associated with each other. The traffic information generation according to claim 30, wherein the block marker is set based on at least one of the above position information and communication operation information in a communication unit mounted on the probe car on-vehicle device. apparatus. A traffic information reproduction device that samples the traffic situation of a target road at predetermined intervals along the road,
The sequence of the sampled data corresponding to the traffic situation is divided into a plurality of blocks so that a plurality of sampled data is included in one block, and encoding is performed in units of the blocks to obtain generated traffic information. Acquisition means;
Reproducing means for decoding the traffic information in units of blocks and reproducing the plurality of sampled data;
A traffic information reproducing apparatus comprising: Traffic information obtained by dividing the sampled data indicating the traffic condition of the target road into blocks so that a plurality of sampled data is included in one block, road reference data indicating the target road and the boundary position of the block, Receiving means for receiving
Traffic information decoding means for decoding the traffic information in units of blocks and reproducing the plurality of sampled data;
Block noise reduction processing means for obtaining a plurality of sampling data included in the range of each block excluding the sampling data added for block noise reduction from the reproduced plurality of sampling data,
A block-by-block correction coefficient calculating means for calculating a correction coefficient for a deviation that occurs in the distance direction of the target road, using information on the boundary position of the block included in the road reference data;
A unit distance correcting unit for each block that specifies an accurate position of the block on the target road using the correction coefficient and positions the plurality of sampling data at the sampling position of the block; Traffic information playback device.

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