GB2180642A - Counting the number of moving bodies - Google Patents

Abstract

A system for counting the number of moving bodies e.g. human bodies, has a one or more linear-array storage-type photodetectors 1,2 for monitoring changes in luminance of a supervisory line or lines A,B through which the moving bodies pass and means for discriminating the number of the moving bodies on the basis of photo data from the supervisory line or lines. The bodies are illuminated and viewed from above and/or below e.g. two lamps 106 set in the floor produce supervisory lines A and B which are viewed by linear CCD arrays 1 and 2 via mirrors 5 and 7. A proportion of the pixels in each array is sampled at intervals of 20 ms and stored in RAM's 12a and 12b. The numbers of data changes in each line and the order of occurrence are monitored by a cpu 16 to identify individual bodies and their direction of travel. <IMAGE>

Description

SPECIFICATION System for measuring the quantity of moving bodies The present invention relates to a system for measur ingthequantityofmoving bodies, which employs a storage type detector of optical radiation for measuring the quantity of number of moving bodies which have passed through a supervisory line or lines, for example, the number of persons who have gone in and out of a building etc. so asto indicatetheob- tained number. Theterm "bodies" should betakento include both animate and inanimate objects.

Conventional systems for automatically measuring the number of moving bodies, such as persons who are going in and out of buildings, include a photoelectric switch system utilizing a light beam, a system utilizing images obtained by a television camera, our a so-called mat sensor incorporating a switch in a floor mat.

However,thesystem utilizing a light beam has the disadvantage that the n u m ber of the bodies can not be discriminated when the persons are passing sideby-side. It has another defect that swinging of arms or legs of persons may possibly cause an error in the measurement. The system using a television camera is disadvantageously complicated intechniquefor pattern recognition of images of the passer-by per sonsfromthe images obtained bythetelevision camera. The mat sensor also involves a problem in durability because of its mechanical switching structure.

In big cities, multistorey buildings and underground shopping arcades, which can admit a great number of peopletherein and which allowthem to go in and out thereof, have been developed. Under these circumstances, the importance ofthe supervision ofthe peoples' conditions in the building has been increased. In particular, it is essential to ascertain the instantaneous accurate number of people within the building so asto guide people safely and effectivelyforevacuation in case of emergency.

The present invention has been made to obviate the problems in techniques and safety control which have been involved in the prior art, and it is an object ofthe present invention to provide a system for measuring the quantity of moving bodies which is capable of accurately discriminating the number of moving bodies, for example, the number of persons who are passing by and which is simple in structure and can be manufactured at a reasonable cost.

In accordance with the present invention, there is provided a system for counting a quantity of moving bodies, comprising a storage type photodetector having a plurality of pixels disposed linearlyfor monitoring changes in the luminance of at least one supervisory line through which the moving bodies pass from above orfrom the underside ofthe or each line in relation to the directions of motion of the moving bodies, and meansfordiscriminatingthenumberof the moving bodies on the basis of photo data ofthe or each supervisory line detected by said storagetype photodetector.

Preferably, the system comprises a storage-type detector of optical radiation provided with a plurality of pixels or picture elements arranged linearlyfor watching changes in luminance of a supervisory line or lines, by which the moving bodies are to pass, from above or under thereof in relation to the moving direction ofthe bodies; and a discriminating means for discriminating the number ofthe moving bodies on the basis of the photo data of the supervisory line or lines detected by the storage-type detector of optical direction.

Byway of example only, specific embodiments of the present invention will now be described, with reference to the accompanying drawings, in which Figure lisa block diagram of a system according to one embodiment ofthe present invention; Figure 2 is a plan view showing the relationship between supervisory lines and a person; Figure 3 is a similar plan view showing anotherexample ofthe relationship between supervisory lines and a person; Figure 4 is an explanatory view of a construction of CCD sensor employable in the present invention; Figure 5is a general chart of data processing buy a calculation processing section shown in Figure 1;; Figure 6is a block diagram ofan exemplarycircuit arrangement of the calculation processing section of Figure 1; Figure 7is an explanatory view showing patterns ofthe relations between the supervisory lines and a person who is passing by the lines; Figures 8A land 8A2, 8B and 8Care flowcharts of the program-controlled processing for measuring the passing-by quantity; Figure 9 is a flowchart of refreshing processing of background reference data; Figures lOA and B are schematic views of another embodiment ofthe present invention, showing an arrangement of the system according to the present invention; Figure 11 is an explanatory view of the operation of the embodiment shown in Figures 1 OA and B;; Figures 12A and B are schematic views of a modification ofthe embodiment of Figure 10; and Figure 13 is an explanatory view of the operation of the embodiment shown in Figures 1 2A and B.

In the following embodiments, the description is made byway of example only, referring to the case wherein persons as moving bodies go in and out of the entrance or exit of a building. However, it is to be noted that the detection object of the present invention is not limited to the movements of persons.

In Figure 1, numerals 1 and 2 are charge coupled devices (hereinafter referred to as CCD sensors) functioning as storage-type detectors of optical radiation.

An optical system for introducing lightto the CCD sensors 1,2 includes a reflecting mirror5, a condenser lens 6 and a lightly silvered plated mirror7 (by which the light coming from the source is divided into a reflected and transmitted beam of certain proportional intensity; hereinafter referred to simply as mirror7). Supervisory lines A, B are provided on a floor 4 on which people pass by. Optical images of the supervisory lines A, B are incident upon the CCD sensors, respectively. The CCD sensors 1,2 develop stored charges whose val ues vary with the I u mi n- anceoftheoptical images, and the values are read and discriminated by a discriminating function of a processor 100 for determining the numberofthepas- sersby.

The CCD sensors 1,2 may be comprised of 2048 photo pixels or picture elements 3a to 3n which are arranged linearly as illustrated in Figure 4. By virtue ofthe optical system as described above, in orderto supervise the lines A, B of 5m, an image of 0.25cm on each of the supervisory lines A, B is set in a reduced scale on each ofthe photo pixels, respectively. When light is incident upon each of the photo pixels 3a to 3n,there is obtained a stored charge proportional to an integration amountofthe incident lightoverapredetermined storing time (exposure time).

in the present invention, as data for calculation of the passing-by quantity, either the whole or a part of the photo data obtained by the CCD sensor as described above can be utilized. For example, every four photo data A1,A5 .... An-1 and B2, B6,... Bn are read out, as shown byshading in Figure 4, by designating jumping addresses from a memory which stores the photo dataforcarrying out the calculation. In the embodiments described asfollows, in view ofthe above description, every 16 photo data in relation with the 2048 photo pixels 3a to 3n are read out to carry out data processing Since the supervisory length on the supervisory line per one photo pixel formed on the CCD sensor is 0.25cm, to read every 16 photo data means to process the photo data at intervals of 4cm on each ofthesupervisorylines.

As onlythe photo data obtained from the photo pixels 3a to 3n arrayed linearly which are read out at given intervals are subjected to data processing, the processing by the processor 100 can be of high speed in spite ofthe great number of pixels per line.

In the case that the moving bodies to be objects of the measurement are persons, the density ofthe photo data employed in the data processing which correspond to the photo pixels 3a to 3n is determined within a range where the passing-by ofthe persons can be detected and is variable within a rangewhere the persons can be detected. However, ifthe data processing speed at the processor 100 is high enough, a series of the photo pixels may, of course, be read out and processed.

The supervisory linesAand Bareformed asfol- lows: the floor (supervisory plane) 4at an entrance or exit etc. of a building is provided with two grooves 1 02a, 1 02b for accommodating light sources, respectively; a plurality of fluorescent lamps 106 are disposed in tandem within each of the grooves along the length thereof. Protective covers 1 08a, 1 08b made of glass etc. are fitted in the openings ofthe grooves, respectively.

As illustrated in Figure 2 (b) which shows the lightsource accommodating grooves 1 02a, 1 02b with the protective covers 1 08a, 1 08b removed therefrom, the plurality offluorescent lamps arranged in tandem provide a light source. The protective covers 1 08a, 1 08b have transparent or translucent windows 11 Oa, 11 Ob which are provided with shading portions to define the supervisory lines A, B, respectively, as illustrated in Figure2(a).

The images ofthesupervisory linesAand Bare reflected by the reflecting mirrorS from the above in relation with the moving directions ofthe persons so as to be incident upon the condenser lens 6. The image ofthe supervisory line A passed through the condenser lens 6 is then reflected by the mirror7 to form an image on the CCD sensor 1, while the image of the supervisory line B passed through the condenser lens 6 is transmitted through the mirror 7 to form an image on the CCD sensor 2.

Any type of optical system may be employed so long as it is capable ofsurelyforming the images of the supervisory linesA and Bonthecorresponding CCD sensors 1,2, respectively.

Adistance D between the supervisory l nesA and B is selected according to the sizes of the moving bodies, while the width W of the supervisory lines A and B is selected according to the size of the entrance or exit.

More specifically, the spacing D between the supervisory lines A and B is determined as follows. The thickness H2 of a human body at a bust is distributed within a range of 14to 24cm in the case of adults and within a range of 9 to 21 cm in the case of children.

Therefore, to determine the passing-by quantity upon detection of a change in luminance caused when a person is passing by the supervisory lines A and B, the spacing D which ensures minimized measuring error is selected based on the thickness of the human body and it may preferably be selected so as notto exceed 9cm which is a minimal thickness of a child's body.

Of course, thewidth W and the distance D may be changed according to the kind of the moving body.

The supervisory lines A and B may be formed by drawing two parallel white lines on the floor 4 as shown in Figure3. If thefloor is made of a material which shows a high reflection effect, such afloor itself can be used for the supervisory region without any special facilities.

Although the supervision is made from above in relation with thefloor4 in the embodiment as illustrated, it may be made from the under side or inside of the floor if there is provision for detecting a change in luminanceofthesupervisorylinesA, B(forexample, if the floor4 is made of transparent materials).

The data stored in the CCD sensors 1,2 are sampled bythe processor 100. In orderto minimize counting errors which may possibly be caused when persons pass by the supervisory lines A, B during the interval between the sampling periods, the sampling rate may be selected so as to be properly higherthan the moving speed of the persons. Ifthe moving speed of the persons is now assumed to be 2.2m/s from the statistics, the storing time of the CCD sensors 1,2 is determined as follows.

First, the distance D between the supervisory lines A and B is set to be 8.5cm which is shorterthan 9cm as specified above by 0.5cm for leaving a margin. The distance D = 8.5cm is divided by the moving speed of 2.2m/s and the sampling is effected two times. Thus, the storing time will be 19.4ms. In this connection, it isto be noted that in case where a fluorescent lamp, for example, of 50Hz is used as a light source,the storing time should be integral multiples of 10msto avoid flickering, though there is no problem when a d.c. lighting-or high-frequency lighting-light source is used. More specifically, the storing time may be set to be 20ms instead of 19.4ms.

The processor 100 is mainly composed of a photoelectric converting section, a background processing section and a calculating section.

The photoelectric converting section includes a pair of AND converters 9a, 9b and a CCD driving circuit 8.

As the CCD sensors 1,2 have 2048 photo pixels 3a to 3n as described above, the reading-out time will be long if the sensors are subjected to reading one by one. By th is reason, two systems of A/D converters 9a, 9b are provided to effect parallel reading ofthe photo signals for enabling high-speed processing.

The CCD sensors 1,2 output photo signals at given intervals of the storing time in responseto a transfer- red clock from the CCD driving ci rcuit 8. The transferred clock reads out the charge stored in the photo pixels 3a to 3n of the CCD sensors 1,2, as a photo signal, at intervals ofthestoring, exposuretime.

The outputs from the respective CCD sensors 1,2 are converted into digital signals corresponding to the respective photo levels by the AID converters 9a, 9b, respectively, to be applied to a multiplexer 10.

The background processing section has a background processing circuit 11, for processing background noises, and RAMs 1 2a, 12b provided afterthe multiplexer 10.

For initialization, the photo data ofthe CCD sensors 1,2 obtained when no person is passing by the supervisory lines A, B are written into RAM 1 2a through the multiplexer 10 as reference data forthe background processing. In the state where the reference data are stored in RAM 1 2a, the photo data ofthe supervisory lines A, B are output in real time from the multiplexerlOtothe background processing circuit 11. The background processing circuit 11 carries out a background processing for obtaining a difference between the reference data stored in RAM 1 2a and the photo data actually obtained.

Another RAM 1 2b continuously writes in photo data obtained in real time and is always prepared to provide latest photo data as background reference data, on the basis of an updating processing aswill be described in detail later, through switching from RAM 12a.

Although the background reference data to be used in the background processing circuit 11 is updated through switching between RAMs 12a and 12b in the embodiment as illustrated, RAM 1 2a may alternatively be used exclusivelyforstoring the background reference data so that only RAM 1 2b may be used for writing in photo data obtained in real time. In this case, the photo data of RAM 1 2b may be transferred to RAM 1 2a storing the background reference data to update the background reference data.

An output from the background processing circuit 11 may be transmitted to the calculating section.

More particularly, the photo data subjected to the background processing by the background processing circuit 11 is written into a buffer storage 1 4a or 14b through a gate circuit 13. The buffer storages 14a, 14b are connected, through a gate circuit 15, to the calculation and processing section 1 6forcarry- ing out calculation for passing-by quantity measure ment.

The reason why two buffer storages 1 4a, 1 4b are provided is to omit a process for synchronizing the timings on the CCD sensorside and the calculating and processing section side and to separate the transferring of the photo data from the CCD sensors 1,2 and the data processing by the calculating and processing section 16. Stated more illustratively, when photo data is being written into one of the buffer storage, for example the buffer storage 1 4a, through the gate circuit 13, another buffer storage 1 4b is connected to the calculating and processing section 16through the gate circuit 15 so thatthe calculating and processing section 16 may read there into the photo data stored in the buffer storage 14b for carrying out data processing.

The calculating and processing section 16 is im plemented, for example, under programmed control by CPU. The calculating and processing section 16 reads in the photo data stored in the buffer storage 14a or l4bwhich is selected by the gate circuit 15to carry outthe calculation forthe passing-by quantity measuring. The calculation by the calculating and processing section 16 is as illustrated in a general flowchart of Figure 5.

The reading-in of the data from the buffer storage 14a or 14b is carried out as illustrated in Figure 4.

More specifically, the photo data 3a to 3n at given intervals are read-in bythecalculating and processing section 16 to carry outthe data processing.

Such data reading is implemented by designating a jumping address to the buffer storage.

The calculating and processing section 16 first reads-in data ofthe lineAfrom the buffer storage 14a or 1 4b as shown by block 18 to detect a change in the data. Subsequently, the reading is switched to the data ofthe line B at block 1 9to detect a change in the data. In the detection of a change in the data at blocks 18 and 19, the positions of the respective linesAand B where such a change in the data has been caused are also detected. The positions ofthe supervisory lines A, B corresponding to the respective pixels 3a to 3n are segmented at intervals of 0.25cm and determined as described before. Therefore, the calculating and processing section 16 can easily identify the positions ofthe lines where a change in data has been caused.

Figure 6 is a block diagram of one form ofthe calculaton processing section 16.

The formation will first be described. 24 is an A line data reading-in ci rcuit for reading-in photo data per one pixel of the line A subjected to the background processing which is transmitted from the buffer storage. 25 is a data change detecting circuit which comparetheA line data with a threshold value for a given data levelfordiscriminating a person orpersonsto detect a data change exceeding the threshold value.

An output from the data change detecting circuit 25 is supplied to a data change number counter 26 to count the number L of data change of the photo pixelsforthe line A. The outputfrom the data change detecting circuit 25 is further supplied to a blank number counter30 after being inverted byaninver- ter28.Theblanknumbercounter30generatesan output to reset the data change number counter 26 when the numberofthe blanks reaches a pred eterminedvalue,forexample2.

The blank number counter 30 functions to reset the countedvalue Lofthedatachangenumbercounter 26 when the data changes detected by the data change detecting circuit 25 do not continue and two pixel data having no data change are obtained successively.

The count output L ofthe data change number counter 26 is supplied to digital comparators 32,34 and 36 and compared with threshold values L = 3, L = Sand L = 18, respectively. A comparison output is generated when the counter output L exceeds the respective threshold.

In the present embodiment, a CCD sensor having 2048 pixels is employed and the number of data to be skipped in reading-in is set as 16 so that the data is detected at intervals of about 4cm on the line. Therefore,thethresholdvalue L=3ofthedigitalcomparator 32 corresponding to a length of 12cm on the supervisory line, the threshold value L = 5 of the digital comparator 34 a length of 20cm on the line andthe threshold value L = 18 a length of 72cm on the line. In other words, the digital comparator 32 generates an output when three data changes continue, the digital comparator34 generates an output by successive 5 data changes and the digital comparator36generates an output by successive 18 data changes.

The output from the digital comparator 32 is supplied to a B line data reading-in circuit 38 to instruct a reading-in operation. More particularly, the B line data reading-in circuit 38 reads in the B line data at a position corresponding to the A line data, i.e., the data stored in the buffer storage 1 4a as shown in Figure 1,through the gate circuit 15, in response to the comparison output ofthe digital comparator 32 when three changes in A line data continue.

An outputfromthe B line data reading-in circuit 38 is suppliedtoadata change d etecti n g circuit40 and compared with a predetermined threshold value set for discriminating a person as in the data change detecting circuit25. When the circuit 40 detects a data change exceeding thethreshold value, it generates a detection output.

41 is a predetermined-number continuation determining circuit which generates an output when a predetermined number, e.g.,three data changes forthe line B are obtained successively.

The formation ofthe predetermined-numbercon- tinuation determining circuit40 is similarto that of the line A side and the circuit 40 comprises a data change number counter 26a, an inverter 28a, a blank number counter 30a and a digital comparator32a.

42 is a moving direction discriminating circuit which discriminates a moving direction in response to the comparison output from the digital comparator 32 and the outputfrom the data change detecting circuit 40 which has detected a change in the B line data at a position corresponding to the A line data.

The discrimination of the moving direction by the moving direction discriminating circuit 42 will now be described referring to Figure7.

Figure 7 iliustrates a change with time, by dividing into time tl to time t3, in case where a person shown by a circle is passing by from a side of the supervisory line Ato a side ofthe supervisory line B. Attime t1,the person is on the lineA, at time t2, the person is across the lines A and B and at time t3, the person has passed the line A and is on the line B.

With respect to such a change with time ofthe moving body in relation with the supervisory lines A and B, a change in the dataforthe supervisory lineA which is positioned at the outset is first inspected in the moving direction discrimination according to the present invention. If three data changes successively occurattimetl,the digital comparator 32 generates an output. The moving direction discriminating circuit 42 discriminates, in response to the output from the digital comparator32,thattheA line data have been changed. A compa rison output from the digital comparator 32 is also supplied to a B line data reading-in circuit 38 to operate the same. The B line data reading-in circuit38 reads inthe B linedata ofthe supervisory line B corresponding to the A line data.

As no data change is obtained at time t1, the moving direction discriminating circuit 42 determines it is pattern 1 based on the fact that the A line data has been changed attimetl and the B line data has not been changed. The moving direction discriminating circuit 42 generates an output indicative that a pattern 1 is obtained attire to to a data memory44.

The moving direction discriminating circuit 42 is inputwith pattern data of a predetermined time be forethetimetl from the data memory 44 and compares the present pattern (pattern 1) with the previous pattern. Since no previous pattern is input in timetl,the moving direction discriminating circuit 42 outputs no counting-up signal indicative of entrance and no counting-down signal indicative of exit.

The digital comparator 34 generates an output when 5 data changes occur successively in case a threshold value L is set as 5. In otherwords,the com- parator 34 determines it is one person when the number ofthe data changes reaches 5. An entrance and exit numbercounter46 counts the numberofentrances and the exits. The counter 46 makes its counting based on the counting-up or down instructions from the moving direction discriminating circuit42.

The results M of the counting is stored in the data memory 44. However, at time since no counting- up or down instructions are output from the moving direction discriminating circuit 42 as described above, the counting operation is not effected.

48 is a counter for counting the number of persons who have passed one line. This one line number counter48 makes its counting in response to a comparison output from the digital comparator 36 having athresholdvalue Lox 18 and makes incrementofthe number N of persons per line in response to a comparison output obtained when 18 data changes occur successively.

In this connection, it is to be noted that there may be such a case that no data change is detected before the number of the data change does not reach the threshold L = 18. Afterthe number of data changes exceedsthethresholdvalue L = Ssetforthedigital comparator 34 and before it reachesthethreshold value L = 18, the one-line numbercounter48 makes increment irrespective ofthe comparison output from the digital comparator 36 if the detection ofthe data change is not obtained successively two times.

An AND gate 50 is provided fora counting operation operative when data changes are interrupted between L = 5 a nd L = 18. The AN D gate 50 ma kes incre mentofthe one-line number counter 48 according to AND of the comparison output from the digital com parator34andthe outputfrom the blank number counter30 when the blank number counter30 counts the predetermined blank numberto generate the output underthe conditions where the comparison output is being obtained from the digital comparator 34. Thus, it is determined that the passerby is one person.

The one-line number counter 48 outputs a signal N to the data memory 44. The signal N is a person number signal representing that the pattern 1 from the moving direction discriminating circuit 42 input attimetl indicates one person. The one-line number counter48 further resets the data change number counter 26. As a result of this, the data change numbercounter26isallowedto renewitscounting operation by succeeding inputs ofthe A line data of the supervisorylineAcontinuouslyoutputfrom the data change detecting circuit 25 after determination of one person.

These operations are repeated so that all the data forthe supervisory lines A and B are input and the number of persons and the pattern attimetl aresto- red in the data memory 44.

Attimet2, since onlytheA line data is normally watched, the data reading is switched to B line data in response to the comparison output from the digital comparator32 when changes in A line data aredetected at time t2 and three data changes continue.

Ifthere are changes exceeding a predetermined range in the B line data at time t2, too, the moving direction discriminating circuit 42 makes a determination of pattern 2 as shown in Figure 7, on the basis of the comparison output from the digital comparator 32 and the detection output from the data change detecting circu it 40.

The moving direction discriminating circuit 42 then generates an output indicating that the pattern 2 is determined at time t2 to the data memory 44. The moving direction discriminating circuit42 is input from the data memory 44 with data of a pattern of a predetermined time before the time t2. More specifically, the moving direction discriminating circuit 42 is input with the pattern 1 which is a pattern ofthe predetermined time before time t2, namely time t1.

The moving direction discriminating circuit42 compares the previous pattern, i.e., pattern 1 and the present pattern, i.e., pattern 2 and determines that the pattern has been changed from pattern 1 to pattern 2 to output a counting-up signal indicative of an entrance to the entrance and exit counter 46.

The entrance and exit counter46 receives the counting-up signal when the comparison output is generated from the digital comparator34to make increment ofthe entering persons. At the same time, the entrance and exit counter 46 outputs a count re sult M to the data memory 44.

The data memory 44 memorizes that the entering person is one upon receipt of the person number signal N from the one-line numbercounter48. The data change number counter 26 is reset by the per son numbersignal N from the one-line numbercoun ter48 and the digital comparators 32, 34 and 36 are initialized to receive succeeding outputs of the A line data from the data change detecting circuit 25.

Theforegoing description is madefortheentrance and the exit will now be described.

Attimet4, if changes oftheA line data are detected and three data changes successively occur, B line data are read-in in response to the comparison output from the digital comparator 32. If there are changes also in the B line data, the moving direction discriminating circuit 42 makes a determination of pattern 2 as illustrated in Figure 7 on the basis of the comparator outputfrom the digital comparator32 and the detection outputforthe B line data from the data change detection circuit 40. The moving direction discrimination circuit42 generates an output in dicative of pattern 2 attime t4to the data memory 44.

The moving direction discrimination circuit 42 is input from the data memory 44 with data of a pattern of a predetermined time before the time t4. However, since no previous pattern is stored in the data memory 44, the moving direction discriminating cir cuit42 outputs no counting-up signal nor countingdown signal.

Then, attimetS, if changes intheA line data are detected and three data changes occur successively, the B line data are read-in in response to the comparison output from the digital comparator32. If there are no changes in the B line data, the moving direc tion discriminating circuit42 determines itisa pattern 1 of Figure 7 on the basis of the comparison output from the digital comparator 32 and generates an output indicating that the pattern is pattern 1 to the data memory 44.

The moving direction discriminating circuit 42 also receives an input indicating that a pattern of the pred etermined time before the time t5, i.e., a pattern 2 at timet4 has been obtainedtodeterminethatthepat- tern has been changed from pattern 2to pattern 1 and outputs a counting-down signal indicative of an exitto the entrance and exit number counter 46. The entrance and exit number counter 46 is input with a counting-down signal when the digital comparator 34 generates a comparison output to make increment ofthe number ofthe exited persons. The count result is output to the data memory 44.

In the foregoing, the entrance and the exit are described while differentiating the occurring times.

However, if there are a plurality of entrances and exits at the same time, the number of the data changes is largerthan that for one person so thatthe A line data sequentially read-in is subjected to determination bythe one-line number counter 48 for dis- criminating one person to reset the data change number counter 26. Another passerby is determined bythe one-line number counter 48. These are repeated from one to anotherend ofthe pixels which are watching the supervisory lineAand the data changes are subjected to the determination or exit by the moving direction discriminating circu it 42 to dis crit innate whether they mean entrance or exit.

Thethresholdvalues L = 3,5 and 18fordetermin- ing asto continuation of counting ofthe data change numberwhich are set in the digital comparators 32, 34 and 36 ofthe embodiment as illustrated in Figure 6 are setaccording to the blank number ofthe data defined by shadows of Figure 4to be read-in from the buffer storage forthe calculation.

In this connection, it is to be noted that the passingby quantity measurement can be effected without any problem when a single person is passing by the two lines, a plurality of persons are passing by the lines in tandem in a direction perpendiculartothe lines, orwhen a plurality of persons are passing side by side but keeping a space therebetween. However, in case where plural persons passing byarejuxta- posed laterally and close to each other or where a baby or child is on the back of a person who is passing by, there is needed a criterion for determining the number of persons who are passing.

The calculating processing ofthe calculation processing section 16 employed in the embodiment of Figure 1 which is operated under programmed control is as shown in theflowchartof Figures8A1 and 2 to 8C and will be described in the following. In this connection, it is to be noted that the calculation processing function ofthe flowchart is identical with that of Figure 6.

In Figure 8A1 and 2, when the system is started, the counter M is initialized and a background reference data is set at block 60. The contents of the counter M is corresponding to the entrance and exit number counter 46. The setting ofthe background reference data is effected in such a manner that either one of RAMs 12a and 12b shown in Figure 1 stores photo data obtained for each ofthe supervisory lines under an initial condition, i.e., underthere are no passersby through the supervisory lines A and B. Such photo data are set as reference data for the background processing circuit 11.

The step proceeds to block 62 to initialize counters Land N to zero which are set as counters in the program corresponding to the data change number counter 26 and the one-line number counter 48 of Figure 6. In the operation intheflowchartasdescri- bed in the following, 128 photo data are processed per line. For this reason, a loop counter I is employed and the loop counter I is also initialized to zero.

After completion ofthe initialization at block 62, the step proceeds to block 64 where a first A line data designated by the loop counter I is input.

Subsequently, at determining block 66, it is inspected as to whether the output is such that the A line data exceeds the threshold value, i.e., the data changes are more than the predetermined level.

When the A line data do not exceed thethreshold value, i.e., the data changes are not of such extent, the step proceeds to block 68.

At block 68, the Ith B line data is skipped and at block 70, the loop counter I is incremented. At determining block 72, it is checked whether I reaches 128 or not and the step returns again to step 64 where the succeeding A line data or 16 data which has been skipped and is designated by the loop counter I is input.

Thus, the processing loop from block 64to 72 is repeated until there is a change in the A line data. If there is no data change even afterthe loop counter reaches its final value, i.e., 128, the step proceeds from determining block72 to determining block74to check if it is a time to refresh the background reference data. If it is a time to make refreshment, the step returns to block 60 to reset the background reference data. Whereas, if it is not a time to make refreshment, the loop counter I is setto zero at block 73 and then the step returns to block 64 to start inputting of new A line data.

When A line data exceeding thethreshold value is obtained in the supervisory cycle of the A line data by the loop counter I, the step proceeds from determining block 66 to block 76.

Block 76 isto determinewhethertwo pixel data are successively input or not. Signals from the pixels are successively obtained, the step proceeds to block78 to incrementthedata change number counter L. The data change numbercounterLcountsthedata change number ofthe Nth person from the end ofthe line A in corresponding relation with the counter N which countsthe number of persons per line aswill be described in detail later. Afterthe increment ofthe data change number counter L has been completed at block 78, the step proceeds to block 80 to check whetherthe counter L reaches 3 or not. When L is less than 3, the step returnsto block 68.

The operations of a loop from block 68 to block 76 and to block 78to increment the data change number counter L are repeated until L reaches 3.

On the other hand, when the step proceeds to determining block 76 in the course of repeating ofthe loop from block 68 to block 80, the counter L is reset to zero as being data changes due to erroneous operation at block 82 if two predetermined blanks are successively obtained. The step then returns to block 68 to repeat the operation. If the number of the blanks is less than the predetermined number, the step proceeds to blocks 78 and 80 to repeat the operation of the loop.

It is confirmed at determining block 80 thatthe counter L has reached 5, Ith B line data designated by the then loop counter I is input at block 84 and the data is checked as to whether it exceeds the threshold value or not.

If the data does not exceed the threshold value, the pattern 1 as shown in Figure 7 is discriminated at block 88. On the other hand, if the data exceeds the thresholdvalue,the pattern 2Of Figure7 isdiscriminated at block 90. Afterthe pattern discrimination at blocks 88 and 90, the moving direction is discriminated at blocks 92 and 94 on the basis of the comparison with the pattern of the predetermined time before which has been registered in the previous line processing.

In the moving direction discrimination, the counting of the entrance and exit is not carried out. The counting is effected after inspecting the continuation conditions ofthe data change number counter L.

Figure 8B is a flowchart to be carried out after Figure 8A1 and 2 and shows a counting operation for entrance and exit after determination ofthe moving direction.

More specifically, the loop counter I is incremented at block 106 and it is determined at block 108whether I is 128 or not. Then, A line data is input at block 110 and it is subjected to inspection as to whetherthe data exceeds the threshold value or not at block 112.

If the data exceeds the threshold value, the data change number counter L is incremented at block 114 and it is determined at block 1 16 whether L reaches 5 or not. If L does not reach 5, the step returns to block 106through block 118to repeat increment of the counter L. Then, when it is determined at block 116 that L reaches 5, the step proceeds to block 122 to count the number M of entrances and exits on the basis ofthe moving direction determined in the flowchartofFigure8A1 and 2.

More particularly, in the case of entrance determination, the entrance and exit number counter M is set as M = M + 1 and in the case of exit determination, it is set as M = M - 1. Of course, if A line data which does not exceed the threshold value is obtained dur ingthe loop processing of determining block 106to block 118, the step proceeds to block 124 to inspect whether the number of blanks reaches the pred eterminednumberornot. If the number of the blanks reaches the predetermined number, data change is determined as being due to erroneous operation and the counter L is reset to zero at block 126 so as notto count the number of entrances and exits.

Figure 8C is a flowchart to be carried out after the operation of Figure 8B, which determines the continuation ofthe data change corresponding to the shoulderwidth of a man fordiscriminating one person to register the position of the person on the line and the pattern obtained in the operation of flowchart as shown in Figure 8A1 and 2.

More specifically, the loop processing of from block 128 to determining block 140 is carried out in such a way that the determination as to whetherthe data change numbercounterl reaches 1 8 or not is made bythe input determination of the A line data. If the counter L reaches 18, the step proceeds to block 142 to register the then one-line number counter N and the pattern. The counter N is incremented at block 144 and the step returns to block 68 of Figure 8A1 and 2.

On the other hand, if A line data which does not exceed the threshold value during the loop operation until the counter L reaches 18, the step proceeds to block 146. If the number of blanks reaches the predetermined number, the step proceeds directly to block 142, skipping determining block 140, to register the position of the person and the pattern. The counter L is reset to zero at block 148.

The processing according to the flowchart of Figure 8C is to determine whether the continuation of the data changes reaches 72cm on the supervisory line which is set by L = 18 or not. For example, if two persons are entering side by side without leaving a space therebetween, one person is discriminated when the data changes corresponding to 72cm have been obtained and another data processing is further carried out to discriminate another person. Thus, the plurality of persons who are passing by can be discriminated from the combined data changes. Furthermore, even if the data changes do not reach 72cm, the passing-by of the person can be discriminated if the data changes exceed 20cm corresponding to L = 5.

In the examples as illustrated in Figures 6 and 8, the value of L is an integer because the data are read while being skipped. Of course no integral number can be used for the value of L. Furtherthe distribution of the shoulder width is within a range of 40 to 60cm in the case of adults and within a range of 20 to 40cm in the case of children.

Figure 9 is a flowchart showing in detail a resetting operation (updating processing) ofthe reference data upon determination ofthe refreshing time atblock74ofFigure8Al and 2.

More particularly, the re-setting of the background reference data is carried out on the basis of the count value of the counter N which counts the number of persons per one line. When the loop counter I reaches the final position where the loop counter becomes 128, the step proceeds to determination block 150. Atthis time, if the one-line number counter N is zero, it meansthatthere is no person passing by the supervisory line and the step proceeds to block 152.

At block 152, the writing operation of RAM 12a or 12b of Figure 1 which has been writing the photo data obtained in real time from the CCD sensor 1,2 is stopped to switch to the setting of the background reference data for the background processing circuit 11 for effecting a refreshing operation (updating processing). After completion of the refreshing operation, the step proceeds to block 1 54to initialize the counters I, N and L into zero and the step moves to a next line data calculating operation through a ready determination at block 156.

As can be understood from the above, so long as there is no person passing by the supervisory line, the latest photo data is used as the background reference data.

In this connection, it isto be noted that the updating processing for the background reference data is carried out when the one-line number counter N is zero and the one-line number counter N is incremented when the data change number L becomes 5 i.e., the number of the data changes exceed 5. Thus, when the number of the data changes is 4 or less, the background reference data is refreshed.

Therefore, the determination of the refreshing may be effected not based on the value of the one-line numbercounterN, but based on the numberofthe data changes.

As the th reshold val ue for determining the data changes for refreshing operation, a threshold value solelyforthe refreshing determination may be em ployedinstead ofusingthethresholdvaluesetfor discrimination of person. In this case, the refreshing operation may be carried out when the data changes arelowerthanthethresholdvalue.Ofcourse,an- other reference or method may alternatively be em ployed for carrying out the refreshing and the present invention is not limited to those as described above. Or, instead of refreshing all the data, partial refreshing processing by a computer may also be employable. In brief, the refreshing may be suitably effected utilizing the change characteristics ofthe supervisory linesAand B.

Although thethreshold values L = 3, 5 and 18 are set for the determination of the direction, entrance and exit number and the shoulder of a person in the foregoing flowcharts, the present invention is not limited to these values and any suitable value may be selected according to necessity. Alternatively, the threshold values may be variable according to necessity without being fixedly set.

Theforegoing embodiments are applied to the number of persons who have entered and exited from a building. However, the present invention is not limited to this application and it may further be applied to measurement of passing of any moving bodysuch asa vehicle,article, orthe like. Inthese cases, the widths of the two supervisory lines A and B may suitably be selected according to the size or velocity ofthe moving body.

In the above mentioned embodiment, the line A is supervised always and the line B is only checked when the output is obtained based from the supervision of the line A. Howeverthesystem can be employed to supervise both of the lines A and B always.

And in such a condition wherein the lines A and B are always supervised the entrance or exit of a person can be determined bythechange of pattern 1 to 3 or3 to 1 as shown in Figure 7. This process will increase the accuracy ofthe detection.

In case where the objectto be measured runs in a fixed direction as an automobile running on a road, there is no need to determine the moving direction of the object. In this case, one supervisory line will suffice.

Figures 10 to 13 show different embodiments of the present invention which have different arrangements ofthe supervisory lines. In these a range ments, the supervisory line is watched by a detector from above orfrom the underside in relation to the moving direction ofthe moving body and the line is adjusted to cross the moving body diagonally.

More specifically, as shown in Figure 10, a mirror5 is so mounted that light from a supervisory line X may cross the moving body diagonally. In other words,the lightfrom the supervisory lineX is set so asto be incident upon the mirror 5 diagonally.

In this embodiment,same orsimilar parts or portions are denoted by same orsimilar numerals or characters to those in the foregoing embodiments.

The operation of the present embodimentwhen the moving body passes by the line will now be described.

Figure 11 is an explanatoryviewshowing the operation ofthe embodiment of Figure 10. In Figure 11, changes with time of a person Hasamovingbody who is passing by the supervisory line X are shown on the left side and signal waveforms corresponding to the respective changes with time are shown on the right side. Attimetl,the person H is moving from the left side as viewed on the drawing which is the inside of a building. Attimet2, the linefrom the supervisory line Xis intercepted by the head ofthe person H so that a signal output is obtained from the photo pixels corresponding to the head as shown on the right side.Attime t3, the light from the supervisory line X is intercepted by the body of the person so that a signal outputfrom pixels ofthe CCD sensor 1 corresponding to the body portion ofthe person H as shown on the right side. At time t4, the person H is further moving towards an exit ofthe building and the light from the supervisory line Xis intercepted by the feet ofthe person Hso that two signal outputs corresponding to the two feet are obtained as shown on the right side. AttimetS, the light is intercepted by one foot ofthe person H so that a signal outputcorresponding to the foot is obtained as shown on the right side.

Since the mounting position ofthe reflecting means is so adjusted that light from the supervisory line X may cross the moving body diagonally, signal outputs corresponding to the head, body and foot or feet ofthe person are obtained with time. Thus, the moving direction ofthe person H can be determined.

Of course, this arrangement ofthe embodiment may advantageously be combined with the processor 100 of the foregoing embodiment to make a precise moving direction discrimination.

Figure 12 is a modification ofthe embodiment of Figure 10. In this modification, the supervisory line X is formed that it may be diagonal with reference to a person who is passing through a path 4. The luminous light from the supervisory line X provided diagonally is reflected by the mirror5 and enters the CCD sensor 1 through the lens 6. In the embodiment as illustrated in Figure 12, since the supervisory line Xis provided diagonally with reference to the path 4, the luminous light from the supervisory line X crosses the person H diagonally as illustrated in Figure 13.

The detection operation ofthis modification will be described referring to Figure 13. At time t1 ,the per- son His moving from the inside of a building towards the supervisory line X. Attimet2,only a left shoulder ofthe person intercepts the supervisory line Xso that a signal output corresponding to the left shoulder is obtained as shown on the right side. At time t3, the body of the person is across the supervisory line Xso that a signal output corresponding to the body ofthe person is obtained. Attime t4, the person is further moved towards the outside and only the right shoul- der intercepts the supervisory line Xso that a signal output corresponding to the right shoulder is obtained as shown in the rightwaveform.

Thus, the the intercepting portions are sequentially changed from the left shoulder of the person H, to the body and to the right shoulder and as a result, the output from the corresponding pixels ofthe CCD sensor 1 are also changed sequentially. In Figure 13, the outputs of the pixels are changed from the right side as viewed on the drawing to the left side and it can be determined from these changes that the person is moving from the inside ofthe building to the outside ofthe building. It can also be discriminated from the pulse duration ofthe signal pulse indicative of the body that how many persons have passed.

In a further modification, the arrangement of Figure 10 may be combined with the arrangement of Figure 12. More particularly, the supervisory line X may be provided SQ asto diagonal with reference to the moving direction ofthe moving body and the in cident angle ofthe luminous light from the supervi- sory line X provided diagonally upon the reflecting mirror 5 may be deflected by a given anglefrom the vertical direction. With this arrangement, the moving direction and the number ofthe persons can be surely discriminated even if the persons as the moving bodies have passed the supervisory line in parallel therewith.

Claims (8)

1. Asystemforcounting aquantityofmoving bodies, comprising a storage type photodetector having a plurality of pixels disposed linearlyfor monitoring changes in the luminance of at least one supervisory line through which the moving bodies pass from above orfrom the underside ofthe or each line in relation to the directions of motion of the moving bodies, and meansfordiscriminating the number of the moving bodies on the basis of photo data ofthe or each supervisory line detected by said storagetype photodetector.

2. Asystemforcounting aquantityofmoving bodies as claimed in claim 1 ,which furthercom prisesastorage meansforstoring photo data obtained from said photodetectorwhen no bodies pass through the supervisory line or lines as reference data; a background processing circuitforobtaining a difference between the data sotred in said storage means and the photo data obtained from said photodetector; a determining means for determining asto whether or not the photo data from the photodetec torischanged morethana predetermined level ora predetermined range; and an updating means for updating the data stored in said storage means using the photo data from the photodetector as reference data.

3. Asystemforcounting aquantityofmoving bodies as claimed in claim 1 or2,wherein two photodetectors are provided, one of the supervisory lines being normally monitored with respect two a change in data thereof, the monitoring ofthe data being switched to another supervisory line when a change in the data has been detected and a moving direction discriminating means being further provided fordis- criminating the moving direction ofthe moving bodies on the basis of a change or changes in the data after the switching.

4. Asystemforcounting aquantityofmoving bodies as claimed in any of claims 1 to 3, wherein a pair of supervisory lines are provided and a pairof photodetectors are provided so as to correspond thereto, respectively.

5. Adeviceforcounting aquantityofmoving bodies as claimed in claim 4, which furthercomprises a reflecting means provided above or below the supervisory lines for reflecting light from the respective supervisory lines in predetermined directions, respectively, and means for letting the light reflected by the reflecting means enterthe re spectivelycorresponding photodetectors.

6. A system for counting a quantity of moving bodies as claimed in any of claims 1 to 5, wherein a light source or sources is/are provided in the supervisory line or lines, respectively, so that the light from the light source or sources incident upon the photodetectors are intercepted by passing of the moving bodies to obtain a change or changes in luminance.

7. Asystemforcounting aquantityofmoving bodies as claimed in any one of claims 1 to 6, wherein the supervisory line or lines is/are monitoring by the photodetector or photodetectors from above orfrom the underside in relation to the moving direction of the moving bodies and the supervisory line or lines cross the moving bodies diagonally.

8. A system for measu ri ng aquantityofmoving bodies, substantially as herein described with refer enceto, and as illustrated in, Figures 1 to 9, Figures 1 to 9 as modified by Figures 10 and 11, or Figures 1 to 9 as modified by Figures 12 and 13.