JP2001109874A - Method and system for processing map data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a target single cross section from three- dimensional map data obtained by a charting device by using CAD technology. SOLUTION: Successively to the input (S11) of parameters regarding single cross-section measurement and the input (S12) of three-dimensional map data, a plane map based upon the three-dimensional data is displayed (S13), section positions are indicated on the display screen (S14), and a sectional position which is parallel to it is generated (S15); and geographical data at the respective sectional positions are extracted (S16) from the three-dimensional map data, the sectional lines at the indicated sectional positions are found (S17) by interpolative calculation by using the geographical data, and the sectional lines and attached information relating to them are outputted (S18).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for processing three-dimensional map data obtained from, for example, aerial photographs, and more particularly to a map data processing method and system for measuring a desired cross section from three-dimensional map data.

[0002]

2. Description of the Related Art Conventionally, the following method has been used as a technique for measuring a desired cross section of a terrain.

(Step 1) A map consisting only of contour lines is created on a paper basis. (Step 2) Read this contour map with a scanner,
Get raster data. (Step 3) Convert the raster data into vector data. (Step 4) Convert the vector data into mesh data. (Step 5) By specifying two arbitrary points, mesh data is searched to generate a section line (ground line of section) and output it.

[0004]

However, this method not only has a complicated process, but also uses only contour data, so that the position of various objects such as a road and a waterway cannot be displayed on a sectional line. There was a point.

The present invention provides a map data processing method and system which can easily measure a desired cross section including the positions of various objects by using CAD technology from three-dimensional map data acquired by a plotter or the like. The purpose is to do.

[0006]

In order to solve the above-mentioned problems, a map data processing method according to the present invention displays a two-dimensional map using input three-dimensional map data, and displays the two-dimensional map on a display screen of the two-dimensional map. And extracting the topographical data of the cross-sectional position specified by the above from the three-dimensional map data, and outputting the cross-sectional line of the specified cross-sectional position using the topographical data.

Further, the map data processing system according to the present invention comprises: means for inputting three-dimensional map data; means for displaying a planar map using the input three-dimensional map data;
Means for extracting topographical data at the designated cross-sectional position on the display screen of the planar map from the three-dimensional map data; and means for outputting a sectional line at the designated cross-sectional position using the extracted topographical data. It is characterized by the following.

According to a more preferred aspect, the map data processing system according to the present invention comprises: means for inputting three-dimensional map data; means for displaying a two-dimensional map using the input three-dimensional map data; Means for generating a second sectional position parallel to the first sectional position specified on the map display screen; means for extracting topographic data of the first and second sectional positions from the three-dimensional map data; From the extracted terrain data, topographic data at a predetermined interval on the first cross-sectional position is obtained by interpolation calculation, and the extracted terrain data and the cross-section at the cross-sectional position designated by using the terrain data obtained by the interpolation calculation are obtained. Means for outputting a line.

[0009] In addition to the output of the cross section line, accompanying information relating to the cross section line may be output.

Further, according to the present invention, a step of inputting three-dimensional map data, a step of displaying a plane map using the input three-dimensional map data, and a step of instructing a cross-section designated on the display screen of the plane map Computer-readable storage of a single-section measurement program consisting of a step of extracting the topographic data of the position from the three-dimensional map data and a step of outputting a sectional line at the designated sectional position using the extracted topographic data Storage medium is provided.

As described above, according to the present invention, the operator instructs the cross-sectional position to be measured on the display screen of the planar map displayed using the three-dimensional map data, so that the necessary topography is automatically obtained from the three-dimensional map data. The data is extracted,
Based on this, it is possible to output a sectional line at a desired sectional position, and further, related information relating to the sectional line by a simple procedure.

In addition, by generating topographical data at fine intervals using interpolation calculation together, it becomes possible to output a more accurate cross section line.

Further, since the section line is output based on the three-dimensional map data, it is possible to obtain a sectional view including objects such as roads and waterways originally included in the three-dimensional map data.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. First, an example of a technique which is a premise of the present invention will be described. In order to acquire map data from an aerial photograph, a device called a plotter (substantially plotter) has been developed. The plotter is a device for producing a stereoscopic image in which a pair of aerial photographic films, for example, which are photographed in an overlapping manner by 60%, are placed on a photographic stand, and are observed individually with left and right eyes through eyepieces. Specifically, first, a projector is installed on the aerial photographic film on the photographic frame with a relative positional relationship similar to the relative positional relationship of the camera at the time of shooting to the aerial photographic film, and this projector uses A similar stereoscopic image is reproduced. This operation is called mutual orientation.

After the mutual orientation, the operation moves to the absolute orientation. In absolute orientation, data of x, y, and z reference points is input to a data acquisition system in a plotter, developed on a display screen of a display for displaying a stereoscopic image of aerial photographic film, and displayed on this display screen. The reference point is matched with the reference point in the stereoscopic image. These orientation operations are performed using an observation target (female mark) determined by a plotter.

When plotting, x,
Three or more reference points with known y and z coordinates are required. For this purpose, an anti-aircraft sign is installed so that the reference point on the ground appears on the aerial photograph, and based on this, the work of adding reference points to each model is performed. This work is called aerial triangulation, and analysis calculations are performed using a computer.

Aerial photographs such as roads and buildings are plotted by touching a target to be plotted with a target and acquiring point data for each change point such as a corner.
As for the contour lines, data is automatically acquired at any specified intervals by touching and moving the measurement target on the ground portion on the aerial photograph.

Thus, acquisition of three-dimensional map data,
A so-called digital mapping is performed to make a drawing. The digital mapping refers to a digital map of analog information and various additional information (topography, land use type, etc.) of a ready-made map, recorded on an electronic storage medium, and reproduced and output as a topographic map figure from the electronic storage medium ( Ministry of Construction
By the Geographical Survey Institute), or by aerial photogrammetry
This refers to the work of measuring map information related to terrain and features in digital form, and constructing a new digital topographic map systematically organized by computer technology, including the creation of original maps such as topographic maps (public construction ministry) According to the digital mapping work procedure in the survey work rules).

The three-dimensional map data obtained by the digital mapping is taken into a three-dimensional CAD system,
Edit as a drawing according to the required specifications. Lines and symbols specified by the Ministry of Construction cannot be handled only by the basic performance of the CAD system. Therefore, the CAD system is provided with new functions through customization.

This customization is roughly classified into two types, one for editing and one for application. The present invention particularly relates to the latter customization. Hereinafter, an embodiment of the present invention will be described based on the above matters. FIG. 1 shows the configuration of a system according to an embodiment of the present invention. This system is roughly composed of a plotting machine 1, a CAD system 2, and an automatic drafting machine 9, which are connected by a bus 10. It should be noted that various interfaces are omitted in the figure.

The plotting machine 1 is as described above. The aerial photographic film 11 is placed on a photographic stand, and this is projected as a three-dimensional image by a projector (mutual orientation). Get 3D map data. The three-dimensional map data is input to the CAD system 2.

The CAD system 2 is configured using a general-purpose computer, and specifically includes a CPU 3, a ROM and a RAM.
Main storage device 4, HDD (hard disk drive)
And the like, an input device 6 including a keyboard and a pointing device (for example, a mouse), a display 7, a scanner 8, and the like. The three-dimensional map data input from the plotter 1 is converted into map data according to required specifications. Edit as The map data created by the CAD system 2 is output by the automatic drafting machine 9 as a paper-based map.

Here, the CAD system 2 measures a section at a designated section position according to a single section measurement program set as one of the application programs based on the present invention, and forms a single section on the display 7. Processing for displaying or outputting as a single sectional view 12 of a paper base via the automatic drafting machine 9 is performed. This single-section measurement program is pre-installed in the external storage device 5 and is downloaded from here to the main storage device 4 for use. Hereinafter, a single-section measurement procedure based on this single-section measurement program will be described. This will be described with reference to the flowchart shown in FIG. First, various parameters relating to single-section measurement are input (step S11). The parameters include the following. -Scale of the vertical axis and horizontal axis of the single sectional view-Reference elevation value H-Interpolation parameters (interpolation interval d, search radius r, weight w) Next, three-dimensional map data is imported from the plotter 1 ( Step S12). Next, a two-dimensional map 2 shown in FIG.
0 is displayed on the display 7 (step S13).

A sectional position (first sectional position) 21 where a single section is to be measured on the display screen of the flat map 20.
Is instructed by the operator (step S14). Specifically, by using a pointing device such as a mouse included in the input device 6 to indicate both end points 22 and 23 of the line that becomes the cross-sectional position 21 on the display screen on the planar map 20, the cross-sectional position 21 is obtained. Is indicated. The designated cross-sectional position 21 is displayed on the display screen of the planar map 20, so that the operator can confirm the designated cross-sectional position 21.

Here, basically, topographical data intersecting with the cross section at the cross section position 21 designated as described above can be extracted from the three-dimensional map data, and a cross section line can be generated and output using the extracted data. However, a cross section line may not be able to be generated with sufficient accuracy (resolution) only from the extracted topographic data. For example, even if there is a large change in the height (Z value) of the terrain due to the presence of cliffs, roads, rivers, etc. between the points where the terrain data is extracted, only the extracted terrain data Then, such a change cannot be reflected on a sectional line.

In order to cope with such a point, in the present embodiment, as described below, the topography data to be crossed with the cross section at the cross section position 21 is obtained by interpolation calculation to improve the accuracy of the cross section line. .

First, as shown in FIG. 4, one or more parallel cross-sectional positions (second cross-sectional positions) 24A, 2 are provided on both sides of the cross-sectional position 21 designated in step S14 for the interpolation calculation.
4B, 24C, and 24D are generated (step S15).
In this example, two parallel cross-sectional positions are generated on both sides of the cross-sectional position 21, but one or three or more parallel cross-sectional positions may be generated on both sides. In generating these parallel cross-sectional positions, the inclination of the cross-sectional position 21 is determined based on the designated cross-sectional position 21, and a line having the same inclination as this inclination and a predetermined interval from the cross-sectional position 21 is obtained. May be set as parallel cross-sectional positions.

Next, the sectional positions 21 and 24A, 24B and 24 are obtained from the three-dimensional map data taken in from the plotter 1.
The terrain data of all points (xyz coordinates) intersecting each section of C and 24D is extracted (step S16). The x, y, and z coordinates (referred to as terrain data extraction coordinates) of the points from which these terrain data are extracted are defined as Xa, Ya, and Za.

Next, from the topographical data of each point extracted in step S16, the topographical data of each point at the designated sectional position 21 is obtained by interpolation calculation using the interpolation parameters (step S17). . Explaining with reference to FIG. 4, the sectional position 21 is divided in the length direction by an interpolation interval d,
Value in the height direction at the point of interval d of the terrain data (Z value)
Is interpolated from the surrounding points where the terrain data within the circle (search range) 25 of the search radius r is obtained.

For example, assuming that a point 26 indicated by a black circle in FIG. 4 is one of the points at the interpolation interval d on the sectional line 21,
The Z value of the point 26 is interpolated from the Z values of the terrain data of n points 27 indicated by white circles of the terrain data extraction coordinates Xa, Ya, and Za within the search range 25 of radius r with the point 26 as the center. calculate. In this interpolation calculation, a weight w that is inversely proportional to the distance from the point 26 is given to the Z value of the point 27.

This interpolation calculation is expressed by the following equation. Zp = (w1 · Zq1 + w2 · Zq2 +... + Wn · Zq
n) Here, Zp is a Z value to be obtained for the point 26, Zq1,
.., Zqn are the Z values of the n points 27, and w
1, w2,..., Wn are weights (weight coefficients) inversely proportional to the respective distances from the point 26 to the n number of points 27, and w
1 + w2 +... + Wn = 1. That is, a greater weight is given to the Z value of a point closer to the point 26 among the points 27.

Finally, the section line along the section position 21 and the accompanying information are output using the Z value of each point of the section line 21 thus obtained (step S18). FIG. 5 shows an output example of the single sectional view 12 including these sectional lines and accompanying information. The single sectional view 12 is displayed on the display 7 and further outputted as a paper-based map by the automatic drafting machine 9.

As shown in FIG. 5, a sectional line 31 indicates a change in the Z value at the sectional position 21. Then, in the example of FIG. 5, the following accompanying information is displayed in the single sectional view 12 in addition to the sectional line 31. First, geodetic coordinates (x, y coordinates) and Z values 32, 33 at both end points of the section line 31 are displayed. In addition, the reference elevation line 3 based on the sea level line 34 and the reference elevation value H given by the above-described parameter input.
5 is displayed. Furthermore, of the area sandwiched between the cross-section line 31 and the reference elevation line 35, the cut area 36, which is the area above the reference elevation line 35, and the embankment, which is the area below the reference elevation line 35. The area 37 is displayed.

[0034]

As described above, according to the present invention, a sectional line at a sectional position designated by an operator from three-dimensional map data or the like acquired by a plotting machine, and further, a single line composed of accompanying information related thereto. One section view can be easily obtained,
In addition, it is possible to output a high-precision section line by using the interpolation calculation, and it is also possible to obtain a single section view including various objects such as a road section and a waterway section.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a system according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a single-section measurement procedure in the embodiment.

FIG. 3 is an exemplary view showing a display example of a planar map according to the embodiment;

FIG. 4 is a diagram illustrating an interpolation calculation according to the embodiment;

FIG. 5 is a diagram showing an output example of a single sectional view in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Drawing machine 2 ... CAD system 9 ... Automatic drafting machine 11 ... Aerial photograph 12 ... Single sectional view 20 ... Plan map 21 ... Instructed sectional position (first sectional position) 22, 23 ... Cross sectional position end point 24A -24D: parallel cross-sectional position (second cross-sectional position) 25: search range 26: point to be interpolated 27: point from which terrain data was extracted 31: cross-sectional line 32, 33: geodetic coordinates and Z value 34: sea surface Line 35: Reference elevation line 36: Cut area 37: Embankment area

Claims (5)

[Claims] A three-dimensional map is displayed using input three-dimensional map data, and topographic data at a cross-sectional position designated on a display screen of the two-dimensional map is extracted from the three-dimensional map data. And outputting a cross-sectional line at the cross-sectional position using a map data processing method. 2. A means for inputting three-dimensional map data, a means for displaying a two-dimensional map using the three-dimensional map data input, and a means for displaying topographic data of a cross-sectional position designated on a display screen of the two-dimensional map. A map data processing system, comprising: means for extracting from the three-dimensional map data; and means for outputting a sectional line at the sectional position using the extracted topographical data. 3. A means for inputting three-dimensional map data, means for displaying a two-dimensional map using the input three-dimensional map data, and a first cross-sectional position designated on the display screen of the two-dimensional map. Means for generating parallel second cross-sectional positions; means for extracting topographical data of the first and second cross-sectional positions from the three-dimensional map data; Means for obtaining topographic data at predetermined intervals by interpolation calculation, and means for outputting a cross-sectional line of the cross-sectional position using the extracted topographic data and the topographic data obtained by the interpolation calculation. Data processing system. 4. The map data processing system according to claim 2, wherein said output means outputs accompanying information relating to said cross-section line together with output of said cross-section line. 5. A step of inputting three-dimensional map data, a step of displaying a plane map using the input three-dimensional map data, and a step of displaying topographic data of a cross-sectional position designated on a display screen of the plane map. A computer-readable storage medium storing a single-section measurement program, comprising: extracting from the three-dimensional map data; and outputting a section line at the designated section position using the extracted topographical data.