JP3166876B2 - Method of converting arc line data into curve part input of graphic processor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for inputting a figure such as a map as coordinate data by means of a figure input device, storing the input coordinate data as digital data in a storage device, forming a database, and using the stored data. The present invention relates to a method for converting an arc into line data at the input of a curved part of a graphic processing device such as a so-called computer mapping system, which is displayed on a display device or displayed on an output device in accordance with the method.

[0002]

2. Description of the Related Art In a mapping system, when a figure drawn on a paper such as a map is input using a figure input device such as a digitizer, a line segment input operation and a curve portion input operation are performed. is necessary. For example, when inputting a map, the sidewalk edge near the intersection is drawn as a curve corresponding to the actual shape, and an input operation corresponding to the curved portion is required.

As a rule of the flat plate surveying method for creating a map, poles are sequentially set up at several places on the side of the sidewalk which are curved as described above, and the survey is faithfully performed. Then, a free-form curve ruler or a cloud-shaped ruler is used. Since it draws while adjusting the shape, it accurately corresponds to the actual curved shape.

However, in a mapping system for performing input using a map of a scale of about 1/500, for example, if the width of the sidewalk is 2 m, the above curved portion on the map is only about 4 mm. Even if this is approximated as an arc, there is no problem in practice. And this arc is
The center position, radius, start angle and end angle can be stored as the arc itself.

However, in a mapping system, affine transformation of coordinate data stored in a database is frequently performed. Therefore, it is not advisable to store the data as a circular arc. In many cases, the curve portion is stored as a set of many continuous line segments so that

For this reason, conventionally, a curve portion is input by a method schematically shown in FIG. That is, when inputting a line as shown in FIG. 6, the worker firstly inputs an input cursor (indicated by an x mark in the figure) at the start point p1 and the end point p2 of the line segment L1 reaching the curved portion L2. Move and input the coordinates of the start point p1 and end point p2 of this line segment as data of the line segment L1. Next, a curved portion L2 from the end point p2 of the line segment L1 to the start point p8 of the next line segment L3
Is divided into a predetermined number by the unit of an eye, and the input cursor is sequentially moved to the positions P3, P4, P5, P6, and P7 on the curve L2 corresponding thereto, and their coordinates are sequentially input. Then, the input cursor is sequentially moved to the start point p8 and the end point p9 of the line segment L3, and their coordinates are input as data of the line segment L3. In this way, the curve portion L2 is sequentially changed from the position p2 to p3, p4, p5, p6,
It was input as a set of line segments from p7 to position p8.

[0007]

However, such a conventional input method has the following problems. a. Since the curved portion is equally divided by the amount of the eye, the lengths of many line segments constituting the curved portion are not uniform. b. In general, the width of a line drawn on the paper is 0.2 mm or more, and the input accuracy of a digitizer or the like is about 0.2 mm. Become. The irregularities of about 0.5 mm are often ignored as not being large in absolute value, but are relatively large for an arc having a radius of about 4 mm.
It doesn't look good despite struggling with typing. An object of the present invention is to solve such a problem.

[0008]

According to the present invention, there is provided a graphic input device for inputting a graphic as coordinate data, and a storage device for storing a graphic based on the input coordinate data. And a coordinate processing means in which a coordinate processing means is interposed between the graphic input device and the storage device, wherein the coordinate processing means outputs a plurality of circular arcs when approximating a curved portion of the graphic with the circular arc. of divided into strings of equal length, the coordinate data of the curved portion so as to output as a set of coordinates of the strings, this time, the arc of the semi
The diameter is used as a criterion for determining the number of divisions.
When the radius is smaller than the radius, the circle is set to the smaller first set value.
Number multiplied by the angle of the arc, and larger than the second set radius
In some cases, the number obtained by multiplying the second set value by the angle of the arc
Is determined as the number of divisions, and the radius is set to the first setting.
If this radius is between the radius and the second set radius, this radius and the second
As the number obtained by multiplying the set value of 3 and the angle of the arc, the above division number
The number of divisions is determined in between, and the number of divisions
To divide the arc and calculate the coordinates of each chord.
Plan.

[0009]

According to the present invention, in the operation of inputting a graphic as coordinate data by a graphic input device, when a curve portion of the graphic is approximated by an arc and output, the coordinate processing means includes a plurality of approximate arcs. , And calculate the respective coordinates. Then, the coordinate data of the curved portion is output as a set of the coordinates of the strings, and stored in the storage device. this
At the same time, the approximated arc can be
To the given string length and the relative angle with the adjacent string
And output them as a set of coordinate data
I do.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings.
First, FIG. 1 conceptually shows a configuration of a graphic processing apparatus to which the line data conversion method of the present invention is applied. Reference numeral 1 denotes a graphic input device such as a digitizer, 2 denotes a cursor, and 3 denotes a cursor placed on a tablet. A figure, such as a map, is drawn on the drawing 3 and its position is designated by the cursor 2 and input as coordinate data. Reference numeral 4 denotes a storage device such as a magnetic disk, and the coordinate data of the graphic input by the graphic input device 1 is stored in the storage device. A coordinate processing means 5 is interposed between the graphic input device 1 and the storage device 4, and the coordinate processing means 5 is provided with a line data converting means 7 to which the method of the present invention is applied.

Further, in the graphic processing device of this embodiment, an arc approximating a curved portion of a graphic is represented by a graphic input device 1.
The coordinate processing means 5 is provided with an arc calculation means 6 for this purpose, which is obtained by calculation with reference to the coordinates of the line segments located on both sides of the curved portion, etc.

A plurality of graphics processing apparatuses having the above configuration are connected to and controlled by a common host computer, but components such as the host computer are not shown.

In the above configuration, when the graphic input device 1 performs the input operation of the graphic drawn on the drawing 3,
In the input of the line segment, the coordinate processing means 5 does not operate the arc calculating means 6 and the line data converting means 7, so that the coordinate data of the start point and the end point of the line segment inputted by the cursor 2 are not changed. Alternatively, the data is stored in the storage device 4 together with the attribute through appropriate processing such as coordinate conversion corresponding to the position, angle, and expansion / contraction.

[0014] On the other hand, the coordinate processing means at the input of the curved portion 5 is circular arc calculation means according to an instruction from the two equal cursor 6
First, the arc calculating means 6 refers to the coordinate data of the line segments located on both sides of the curve part to be input by the arc calculating means 6 to calculate an arc approximating the curve part. The arc is divided into a plurality of equal-length chords by the line data converting means 7, and the respective coordinates are calculated. Then, the coordinate data of the curved portion is output as a set of the coordinates of these strings, and stored in the storage device 4. The specific operations of the arc calculating means 6 and the line data converting means 7 to which the line data converting method of the present invention is applied will be described below with reference to flowcharts and schematic diagrams.

FIG . 2 shows a case where an arc is divided by the inputted division number.
It is a flowchart which shows the specific operation | movement of the line data conversion means 7 to which the method of converting into line data was applied with operation | movement of the arc calculation means 6, and the step enclosed by "6 @" shows operation of the arc calculation means 6, and " Steps enclosed by “7｝” correspond to the operation of the line data converting means 7. FIG.
FIG. 4 is a schematic diagram showing each operation. First, FIG.
The operation of the arc calculating means 6 will be described with reference to FIG.

[0016] First in step S101, the front and rear of the line segment AB of the curve portions, CD is input. Line segments AB and CD before and after this
Are the coordinates of A, B, C, and D in FIG. 3, (Xa, Y
a), (Xb, Yb), (Xc, Yc), and (Xd, Yd).
In step S101 or steps before and after this step,
The command corresponding to the input of the curve portion is appropriately given by the graphic input device 1.
To the coordinate processing means 5.

[0017] Then in step S102 calculates the coordinates of the front and rear of the line segment AB, the intersection of the CD P (Xp, Yp). This intersection P
Can be calculated, for example, by solving the following simultaneous equations. (Xa-Xb) Yp + (Yb-Ya) Xp + YaXb-XaYb = 0 (Xc-Xd) Yp + (Yd-Yc) Xp + YcXd-XcYd = 0

[0018] In step S103 Next, each line segment AB, the new two-point B in contact with the circle at the CD ', C' coordinates (Xb ', Y
b ′) and (Xc ′, Yc ′) are calculated. The value obtained by dividing the sum of the distances between the intersection points P and the end points B and C on the intersection point P side of each input line segment by two into two is the distance between the intersection points P and the new end points B 'and C'. It is calculated so that That is, PB '= PC' = (pb + pc)
Calculate the end points B 'and C' that are / 2. This is L1 = PB, L2 = C
Assuming that P and L = (L1 + L2) / 2, the following equation can be obtained. Xb '= (L / L1) (Xb-Xp) + Xp Yb' = (L / L1) (Yb-Yp) + Yp Xc '= (L / L1) (Xc-Xp) + Xp Yc' = (L / L1) (Yc-Yp) + Yp

[0019] Next, at step S104, the end point B calculated at step S103 ', C', and registered as the end points of each line segment,
Hereinafter, the line segment sandwiching the curved portion is changed to AB ', C'D and handled.

[0020] Next, at step S105, the above-mentioned end point
A perpendicular is drawn from B 'and C', and the coordinates of the intersection O (X ₀ , Y ₀ )
And the distance from the end points B 'and C' to the intersection O, that is, the end point
The radius R of the circle tangent to the line segments AB 'and C'D in B' and C 'is calculated. The coordinates (X ₀ , Y ₀ ) of the intersection O can be calculated, for example, by solving the following simultaneous equations: (Ya−Yb ′) Y ₀ + (Xa−Xb ′) X ₀ − (Ya− Yb ') Yb'-(Xa-X
b ′) Xb ′ = 0 (Yc′-Yd) Y ₀ + (Xc′-Xd) X _0- (Yc′-Yd) Yc ′-(Xc ′
-Xd) Xc ′ = 0 The radius R can be calculated using the Pythagorean theorem shown by the following equation. R ² = (Xb′-X ₀ ) ² + (Yb′-Y ₀ ) ²

[0021] Through the steps S101~S105 explained above, an arc that approximates the curved portion is calculated. In the method of the arc calculating means 6, regarding the input of the curved portion, the input corresponding to the curved portion is unnecessary, and only the coordinates of the end point need to be obtained. Work is easy.

The method of calculating the arc in the arc calculating means 6 is, in addition to the above-described method, inputting coordinate data of a line segment located before and after a curve to be inputted and the radius of the arc. Appropriate methods such as a method of calculating from data, a method of inputting coordinate data of a line segment located before and after a curve to be input and a coordinate of one point on the curve and calculating from these data are applied. can do.

Next, by dividing the circular arc division number input line
Specifics of the line data conversion means 7 to which the data conversion method is applied
The operation will be described. First, in step S106, it is determined whether the point D is on the left side or the right side of the vector AB '. At this time, when it is on the left side, θ0 described in FIG. 4 is positive, and when it is on the right side, it is negative. This determination method is, for example, when F = (Ya-Yb ') Yd- (Xa-Xb') Xd + YaXb-XaYb, and when the value of SGN (F) × SGN (Ya-Yb) is positive, There is a point D, and when it is negative, it can be determined that it is on the right side. SGN is a function that displays only positive and negative signs.

[0024] is in step S107 and then, calculates the arc angle theta _0. The angle θ ₀ can be obtained by the following equation using the cosine theorem of a trigonometric function. | θ ₀ | = arccos [1-｛(Xb′-Xc ′) ² + (Yb′-Yc ′) ² ｝ /
2R ² ] Accordingly, when shown together with the positive / negative judgment in step S106, the arc angle θ ₀ can be expressed as the following equation. θ ₀ = SGN (F) × SGN (Ya-Yb) · | θ ₀ |

[0025] Next, at step S108, the system of coordinates of the reference, for example, the relative X-coordinate, arc start angle θs
Is calculated by the following equation. θs = arctan ｛(Yb'-Y ₀ ) / (Xb'-X ₀ )｝

[0026] Then entering the division number n of the arcs at step S109. The input of the division number n can be performed at an appropriate step preceding this step S109, for example, at an appropriate place such as step S101, or between step S105 and step S106.

[0027] Then in step S110, based on the value calculated at the above step, and calculates the coordinates of each string by the following equation. That is, assuming that Δθ = θ ₀ / n, the coordinates (Xqi, Yqi) of the i-th (where i = 1 to n−1) chord are calculated by the following equations, respectively. Xqi = cos (θs + iΔθ) + X ₀ Yqi = cos (θs + iΔθ) + Y ₀

[0028] Through the above steps S106 to S110, the division number n of the arc that approximates the curved part, entered
Can be divided into a plurality of equal-length strings, and a set of coordinates of these strings can be calculated. Line consisting of these steps
In the data conversion method, the number of divisions n is specified by input.
However, in the present invention, the line data is determined using the radius R of the circular arc as a determination condition.
It is determined by the data conversion method. That is, FIG.
5 is a flowchart showing a specific operation of the embodiment of the line data conversion means 7 corresponding to such a method. In this method, steps S501, S502, S503 correspond to the line data conversion means corresponding to the line data conversion method described above. 7, steps S106, S107,
Same as S108.

[0029] Then, in this line data reduction method, in step S504, compares the radius R of the arc calculated at arc calculating means 6, etc., the radius R ₀ set in advance and (first setting radius) .

[0030] Comparison of the results, in the case of R ≦ R _0, the step S
Branches to 505, in the step S505, determines that division number n of the number obtained by multiplying the arc angle theta ₀ obtained in the first set value a ₀ the smaller the above step S502. In other words, a ₀ · θ ₀ → n
And

[0031] On the other hand, the results of in comparison to step S504,
If R> R0, the process branches to step S506, where the radius R of the arc is again set to the second set radius K / a.
Compare with In practice, the value obtained by multiplying the radius R of the arc by the set value a (third set value) is compared with the set value K.

The comparison of the results, in the case of a · R> K, the step
The process branches to S508, and the number obtained by multiplying the set value K (second set value) by the angle θ ₀ of the arc is determined as the division number n. That is, K
Let θ ₀ → n.

[0033] On the other hand, the results of in comparison to step S506,
If a · R ≦ K, the process branches to step S507, and the number obtained by multiplying the radius R of the arc by the third set value a and the angle θ ₀ of the arc is determined as the division number n. That is, a · R · θ ₀ → n.

After the division number n is determined in this way,
In step S509 similar to step S110, the coordinates of each string are calculated.

[0035] Next will be described a specific example of the setting values described above. In general, the display device in the mapping system can be displayed at any scale, but usually 1 /
It is often used at a scale of 500. At this scale, for example, the radius of the sidewalk edge is at least 2 mm, and often 3 to 4 mm. With such a radius, for example, a division number of about 10 for an arc of 90 degrees is appropriate in terms of a balance between appearance and required storage capacity. In consideration of such a point, in the embodiment, the first set radius R _{0 is} 5 mm and the first set value a ₀ is 1/9. At these settings, up to R = 5 mm, 90
The number of divisions for the arc of degree is n = a ₀・ θ ₀ = 90 ・ 1/9 = 10 and 10
Will be split into strings. In this case, when R = 5mm, the string length is 0.78mm, for example, as a display device
Since the display of the CRT is about 0.2 mm dots and the output of the electrostatic plotter as an output device is about 0.1 mm dots, a shape that is sufficiently satisfactory as a circular arc is usually obtained visually. Of course, the set value can be changed so that the number of divisions n becomes greater than this, and this may be determined based on the balance between appearance and required storage capacity as described above.

On the other hand, need R to enter the arc than 5mm, for example sidewalks and important roads national roads such as occur for places where the road is curved. At such a large radius, attention is paid to the fact that the relative angle between adjacent strings is not so much visually noticeable when the relative angle is less than 1 degree. In this embodiment, the second set radius K / a is set to 50 mm, and Each set value is determined so that the angle is 9/10 degrees. That is, the third set value a = 1/45 and the second set value K = 10/9.

[0037] By determining the set value as described above, for the arc R is 5 mm to 50 mm, continue to increase the number of divisions n in proportion to R, while the strings and fixed length 0.78mm Become.

In the line data conversion method of the present invention described above, the number of arc divisions is determined in consideration of the radius of the arc and the length of the chord and the relative angle between adjacent strings .
The division angle is automatically set according to the determined number of divisions.
First, select the division angle from a table etc.
And split it according to the selected split angle.
Arc division can be performed without fractional processing , and thus good looking and efficient in terms of required storage capacity.

[0039]

As described above, according to the present invention, in the case where a curve portion drawn as a curve corresponding to an actual shape on a map or the like is approximated as an arc and converted into coordinate data, this arc is It is possible to input as a chord without any irregularities automatically divided equally by the determined number of divisions , and the input operation is easy, and the division angle can be selected first from a table etc.
To the end as if splitting by the selected split angle.
No number processing is required, so it looks good and requires the required storage
It is possible to perform efficient arc division in terms of quantity
effective.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram conceptually showing the configuration of a graphic processing apparatus to which the method of the present invention is applied.

FIG. 2 is a line data conversion having steps common to the present invention .
6 is a flowchart illustrating a specific operation example of a line data conversion unit corresponding to the method and a specific operation example of an arc calculation unit that calculates an arc to which the method is applied based on input coordinate data.

FIG. 3 is a schematic diagram showing an operation of an arc calculating means in the example shown in FIG. 2;

FIG. 4 is a schematic diagram showing an operation of a line data converting means in the example shown in FIG. 2;

FIG. 5 is a flowchart showing a specific operation of the embodiment of the line data conversion means corresponding to the line data conversion method of the present invention .

FIG. 6 is a schematic diagram showing a conventional method of inputting a curved portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Graphic input device 2 Cursor 3 Drawing 4 Storage device 5 Coordinate processing means 6 Arc calculation means 7 Line data conversion means

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06T 11/20 110 G06T 11/60 300 G06T 11/80 G09G 5/20

Claims (1)

(57) [Claims] 1. A graphic input device for inputting a graphic as coordinate data, a storage device for storing a graphic based on the input coordinate data, and a graphic processing device interposed between the graphic input device and the storage device. In the processing equipment,
The coordinate processing means divides the arc approximating the curved part into a plurality of equal-length chords and outputs the coordinate data of the curved part when the curve part of the figure is approximated by an arc and output. so as to output as a set, this time, the arc of the semi
The diameter is used as a criterion for determining the number of divisions.
When the radius is smaller than the radius, the circle is set to the smaller first set value.
Number multiplied by the angle of the arc, and larger than the second set radius
In some cases, the number obtained by multiplying the second set value by the angle of the arc
Is determined as the number of divisions, and the radius is set to the first setting.
If this radius is between the radius and the second set radius, this radius and the second
As the number obtained by multiplying the set value of 3 and the angle of the arc, the above division number
The number of divisions is determined in between, and the number of divisions
Divide the arc and calculate the coordinates of each chord.
Of a circular arc in the input of a curved part of a graphic processing device
Data conversion method