JP2001142393A - Method for preparing green coverage ratio map or green view map - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a green coverage ratio or a green view ratio by the evaluation of a surface area in a very simple manner and at low cost in terms of a surface. SOLUTION: A green view map preparing method comprises steps of obtaining numerical map altitude mesh data having the mesh of a prescribed size, ground surface height mesh data and ortho-photo data prepared from the numerical three-dimensional model by aerial photographing with respect to an object region, interpolating the numerical map altitude mesh data so as to have the same size as the mesh of the ground surface height mesh data, generating a three-dimensional curved surface with the numerical map altitude mesh data as a ground level and with the ground surface height mesh data as a ground surface, mapping ortho-photo data on the ground surface as color information, fixing a human visual point at a prescribed height from the ground level at a mesh central point in each mesh and setting a visual point direction at a human visual field angle and setting a projection surface orthogonal with the visual point directional vector, and extracting color information from the ortho-photo data mapped on a ground surface projected on the projection surface as a picture to obtain a green view ratio in the direction of the visual point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for obtaining a green coverage ratio and a green visibility ratio of a city, which are one parameter for evaluating a city environment.

[0002]

2. Description of the Related Art Conventionally, the evaluation of green in a city has been carried out in order to create a city in consideration of comfort and disaster prevention, and the distribution of a green covering, a street tree, a green road, and the like, and a green vision at a specific point. It is based on rates. Of these, the planar distribution state of the green cover is conventionally evaluated by a green viewing ratio, which is an area ratio between a two-dimensional green portion projected on the map and a non-green portion.

On the other hand, the green viewing rate is a ratio of green that can be identified in a visual field when the surroundings are viewed from a human viewpoint, and it is more appropriate to express the comfort of a city than the green viewing rate. It is considered. Conventionally, the evaluation method using the green viewing rate is to arrange the current situation photograph at a certain point and the montage photograph after greening as a simulation, and to compare the visual image and the green coverage ratio relatively. there were.
In addition, the basic data was obtained by measuring the area of a green portion in a photograph based on a photograph taken from an actual human viewpoint position in a field survey. This method
It is possible to obtain a green viewing rate with a high degree of accuracy for a specific point, or to specifically show an image after greening at that point. Therefore, for the whole city, it is considered that the green visibility is more practical than the green coverage itself from the viewpoint of urban comfort.

[0004]

However, the conventional method for obtaining the green viewing ratio is to create a snapshot at an appropriate place in a city and obtain the green ratio in the photograph in a spot-like manner. According to such a conventional method, it is difficult to obtain a green viewing rate continuously in a two-dimensional manner in order to evaluate the entire city.

[0005] On the other hand, the conventional green coverage is the ratio of green in the map area, and shows an evaluation value relatively close to the sense of green vision in flat terrain. At such a point, the evaluation value deviates from the sense of green vision.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to evaluate the greening in terms of area, that is, as close as possible to a real human sense of green from a human viewpoint, over the entire city. An object of the present invention is to provide a method for creating a green cover map or a green vision map by surface area evaluation, which can give a value.

[0007]

According to one aspect of the present invention, there is provided a method for creating a green cover map based on a surface area evaluation over a target area, wherein a mesh of a predetermined size is provided for the target area. Acquire digital map elevation mesh data, ground height mesh data and orthophoto data by a numerical three-dimensional model of the ground by aerial photography, and make the digital map elevation mesh data the same mesh size as the mesh of the ground height mesh data. To generate a three-dimensional curved surface using the digital map elevation mesh data as the ground surface and the ground height mesh data as the ground surface, mapping the orthophoto data on the ground surface as color information, and And determining a green coverage ratio by evaluating the surface area of the surface.

According to another aspect of the present invention, there is provided a method for creating a green-vision map over a target area, comprising: a digital map elevation mesh data having a mesh of a predetermined size; Surface numerical value 3
Obtain ground height mesh data and orthophoto data by a three-dimensional model, interpolate the digital map elevation mesh data to have the same mesh size as the mesh of the ground height mesh data, and convert the digital map elevation mesh data to the ground surface. A three-dimensional curved surface is generated using the ground height mesh data as the ground surface, and the orthophoto data is mapped as color information on the ground surface. Determine the viewpoint and set the viewpoint direction with the human viewing angle,
Setting a projection plane perpendicular to the viewpoint direction vector, and extracting color information from orthophoto data mapped on the ground surface projected as an image on the projection plane to obtain a green viewing rate in the viewpoint direction; Is provided.

According to one embodiment of the present invention, the viewpoint directions are at least four directions of north, east, south and west.

According to another embodiment of the present invention, the green viewing rate is obtained by scanning all pixels of an image projected on the projection surface, and extracting color information extracted from each pixel into R (red), G
As (green) and B (blue), the number of pixels satisfying G> R, B is counted, and is given by the ratio of the counted total number of pixels to the total number of pixels on the projection surface.

According to another embodiment of the present invention, the value of the green viewing ratio is displayed in different colors.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in more detail with reference to the accompanying drawings according to embodiments and examples of the present invention.

FIG. 1 is a flow chart for explaining a method for preparing a green coverage map or a green vision map by surface area evaluation according to the present invention. As shown in the flowchart of FIG. 1, according to the method of creating a green-view map as one embodiment of the present invention, first, digital map elevation mesh data of a target area for which a green-view map is to be created, Acquire ground surface height mesh data and orthophoto data based on a numerical three-dimensional model of the ground surface by photographing.

[0014] The digital map elevation mesh data is the national land numerical information elevation mesh data (50m x
50m). The ground level mesh data based on the three-dimensional numerical model of the ground surface by aerial photography may be obtained by a so-called AUTO-3D method, for example, as disclosed in Japanese Patent Publication No. 8-16930. That is, it is obtained by aerial photography including the target area and ground level measurement (three-dimensional measurement) by AUTO-3D based on aerial triangulation. The orthophoto data (photo map image data) is created using the DEM data obtained by the above-mentioned surface height measurement and the aerial triangulation results.

Thus, according to one embodiment of the present invention,
For the target area, obtain a 50m mesh digital map,
In addition, AUTO-3D data and orthophoto data are created.
Interpolation is performed to have the same mesh size as the mesh created by UTO-3D. FIG. 2 is thus obtained,
An example is shown in which the altitude value of the created altitude data is expressed in shades of shade, and the administrative boundaries of the target area are superimposed on this.

Next, from the photograph map image data, for example,
Green is automatically extracted by the local threshold setting method, and the erroneously extracted and unextracted portions after the automatic extraction are corrected by manual reading to create a green coverage map based on a two-dimensional area ratio. Then, a three-dimensional curved surface is generated by a difference calculation using the 50 m elevation mesh of the digital map as the ground surface and the AUTO-3D data as the ground surface. Further, orthophoto data is mapped as color information on the ground surface represented as a three-dimensional curved surface in this manner. This is performed by superimposing the green cover map obtained as described above. Can be. FIG. 3 shows an example in which orthophoto data is mapped as color information on the ground surface. Then, a green coverage map based on the surface area evaluation can be created by obtaining the green coverage ratio based on the surface area evaluation in each mesh.

According to this embodiment of the present invention, a viewpoint field is set using the green three-dimensional model created as described above, and a green visual rate is calculated using a computer graphic production method. Go. As illustrated in FIG. 4, a mesh of an arbitrary size is set in the target area, and the mesh is
For example, scanning is performed in order from the southwest end to the northeast end. With respect to an arbitrary mesh, viewpoints in four directions of north, east, south, and west are set at the mesh center point.

FIG. 5 is a view in which FIG. 4 is viewed from the cross-sectional direction. The viewpoint 1 is a point at a height of 1.5 m (ground position of human) from the ground plane 2 at the center point of the mesh. A viewpoint direction is set at a viewing angle 3, and a projection plane 4 orthogonal to the viewpoint direction vector is set.

As illustrated in FIG. 6, a three-dimensional ground surface 5 is projected on the projection plane 4 as an image. Since the orthophoto is mapped on the ground surface 5, R (red), G (green), and B (blue) color information can be extracted from the pixels of this image. All the pixels of the image are scanned, the number of pixels (G> R, B) is counted, and the total number of pixels Ng is obtained. The ratio of this to the total number of pixels Na on the projection surface, Ng / Na × 100, is determined, and this is defined as the green viewing rate at that point and direction. This is done every four directions for all meshes.

After scanning all the meshes, each mesh is given a value of the green viewing ratio in four directions, and a green viewing map is created by numbers. If this value is classified by color, it is possible to express a macro tendency of the green viewing rate in the target range as a green viewing map. FIG. 7 shows an example of such a green-vision map. In FIG. 7, a dark color tone indicates a point having a high green visibility rate, and a light color tone indicates a point having a low green visibility rate.

Further, at the time of calculating the green viewing rate at each point, since the process goes through the process of creating a computer graphic image, it is possible to make this image into a database.

Further, according to the present invention, a green-vision map having a perspective effect is obtained by providing a distribution map in which a green-vision ratio weighted by a distance to green within a 360-degree visual field is provided for each arbitrary grid. You can also.

Further, in the above-described embodiment, the four directions of green visibility are obtained at each point. However, the present invention is not limited to this, and the north, northeast, east, southeast, south , The southwest, the west, and the northwest can be represented as eight types of distribution maps by giving a green viewing rate within a 90-degree viewing angle for each of the eight directions.

Further, it is also possible to obtain a direction in which the green gaze is maximum for each arbitrary grid and express it as a vector diagram to obtain a maximum green gaze direction map.

[0025]

As an evaluation value of the degree of green appearance, which is one parameter for evaluating the environment in a city or the like, the green coverage or green visibility by a surface area evaluation showing a value closer to reality is obtained in a very simple manner. In addition, it can be provided at a low cost.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method for creating a green coverage map or a green vision map by surface area evaluation according to the present invention.

FIG. 2 is a diagram in which altitude data created by using digital map mesh data and AUTO-3D mesh data in order to carry out the method of the present invention are expressed in shades of light and shade.

FIG. 3 is a diagram exemplifying a state in which orthophoto data is mapped as color information on a three-dimensional curved surface generated by using a digital map elevation mesh as a ground surface and AUTO-3D data as a ground surface in the implementation of the method of the present invention. .

FIG. 4 is a diagram exemplifying a viewpoint position for obtaining a green viewing rate in the embodiment of the present invention.

FIG. 5 is a view of FIG. 4 viewed from a cross-sectional direction.

6 is a diagram showing an example of a three-dimensional image of the ground surface projected on the projection plane of FIG. 4;

FIG. 7 is a diagram illustrating a green vision map obtained in the embodiment of the present invention.

[Explanation of symbols]

 1 viewpoint 2 ground surface 3 viewing angle 4 projection surface 5 ground surface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C032 HA02 5B050 BA09 BA17 EA28 FA05 FA06 9A001 HH29 HH31 JJ11 KK60

Claims (5)

[Claims] 1. A method for creating a green cover map by evaluating a surface area over a certain target area, comprising: a numerical map elevation mesh data having a mesh of a predetermined size; Obtain ground height mesh data and orthophoto data by a three-dimensional model, interpolate the digital map elevation mesh data to have the same mesh size as the mesh of the ground height mesh data, and convert the digital map elevation mesh data to the ground surface. And generating a three-dimensional curved surface using the ground height mesh data as a ground surface, mapping the orthophoto data on the ground surface as color information, and obtaining a green coverage by evaluating a surface area in each mesh. Method. 2. A method for creating a green-vision map over a target area, comprising: using a digital map elevation mesh data having a mesh of a predetermined size for the target area; Obtain ground surface mesh data and orthophoto data, interpolate the digital map elevation mesh data so as to have the same mesh size as the mesh of the ground surface mesh data, and use the digital map elevation mesh data as the ground surface and the ground surface. A three-dimensional curved surface is generated using the high mesh data as the ground surface, and the orthophoto data is mapped as color information on the ground surface. In addition, the viewpoint direction is set by the human viewing angle, and the projection plane orthogonal to the viewpoint direction vector is set. Extracting green information in the direction of the viewpoint by extracting color information from orthophoto data mapped on the ground surface projected as an image on the projection plane. 3. The viewpoint direction is at least north, east,
3. The method according to claim 2, wherein the orientation is four directions, south and west. 4. The green viewing rate is obtained by scanning all pixels of an image projected on the projection surface, and defining color information extracted from each pixel as R (red), G (green), and B (blue). , G> R, B, the number of pixels being counted, and given by the ratio of the total number of pixels counted to the total number of pixels on the projection surface. 5. The method according to claim 2, wherein the value of the green viewing rate is displayed in different colors.