JP2570926B2 - How to make satellite view maps - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for creating a satellite line-of-sight map, which distinguishes between areas where radio waves from satellites are unreachable and areas of arrival.

[0002]

2. Description of the Related Art Generally, in a city where buildings are densely packed, radio waves from satellites are cut off, so that reception of radio waves from broadcast satellites and transmission and reception to communication satellites and mobile satellites may be hindered. In such a case, it is necessary to improve the reception condition by installing a terrestrial relay station in the disturbed area or area. Therefore, it is first necessary to clarify the area where radio waves from this satellite do not reach, and if so, the installation location of the satellite broadcast receiving antenna, the broadcasting mobile satellite relay station antenna, and the service of the communication satellite or mobile satellite communication The area can be clarified.

Conventionally, as a method for responding to such a demand,
There are a method of actually measuring the received power on all roads and a method of using an aerial photograph to visualize a non-arriving area of a radio wave from a satellite caused by a building or the like. As the latter method, IEICE Transactions B-II Vol. J73-B-II No.
7pp. 328-335 (July 1990) There is a visualization method of a non-arrival area of a radio wave from a satellite indicated in "Propagation characteristics in mobile reception of satellite broadcasting in a city". This is 1
Taking advantage of the fact that the propagation state in the high frequency band above 0 GHz depends on the visibility of the radio source, the satellite is replaced with a light source such as the sun or the moon in order to present the visibility of the satellite on the road, and approximately visualized. Is what you do.

FIG. 7 is a block diagram of a conventional method. In FIG. 7, reference numeral 2 denotes data indicating the position and altitude of a target satellite, and reference numeral 7 denotes data indicating the position of the sun throughout the year. Based on these data, the date and time at which the satellite position and the sun position match the apparent position are calculated in step 44. In step 45, an aerial photograph is taken at the date and time according to the output in the apparent position coincidence date and time calculation step 44 to visualize the satellite line-of-sight map. In step 46, the area and length of the sun's shadow in the aerial photograph, which is a satellite perspective map, are investigated, and the ratio to the road is calculated.

[0005] The conventional method of creating a satellite line-of-sight map requires an aerial photograph of the time when the apparent position of the target satellite coincides with the sun as described above. Must be taken at the opportunity to pass through. This shooting opportunity was about 10 minutes a day, and about two weeks each in spring and autumn.

[0006]

As described above, the conventional satellite line-of-sight map making method is limited to the occasion where the position of the sun and the position of the satellite are apparently coincident with each other. In addition, satellites located at different positions need to be photographed again by the above-mentioned method, which is poor in versatility. It also takes time and money. In addition, when evaluating the line of sight on the road from the aerial photograph taken, the output is an aerial photograph, so the area and length of the shadow on the road must be investigated, and it takes time to calculate the evaluation value. There was a problem.

The present invention has been made to solve the above problems, and has as its object to easily create a line-of-sight map of a plurality of arbitrary satellites using aerial photographs and maps.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method and apparatus for creating a line-of-sight map of a satellite, comprising: means for extracting a shadow portion of sunlight from image data such as an aerial photograph and inputting the extracted information; Means for inputting lines and road maps, means for calculating the height of the building from the extracted shadow of the sun and the bottom of the building, and further inputting the altitude and position of the satellite, and the height and building of the building A means is provided for calculating a non-reachable area of a radio wave from a satellite from the outline of the bottom of the object and calculating a non-reachable area of a radio wave on a road map.

[0009]

According to the method and the apparatus for preparing a satellite line-of-sight map according to the present invention, the height of a building is calculated from image data such as aerial photographs and a contour drawing of the bottom of the building, and is stored in a database. From these databases and the position / height data of an arbitrary satellite, a satellite radio wave non-reachable area viewed from the satellite is calculated.

[0010]

【Example】

Embodiment 1 FIG. FIG. 1 is an overall configuration diagram of an embodiment of a satellite line-of-sight map according to the present invention. In FIG. 1, reference numeral 1 denotes an aerial photograph, and 2 denotes data related to an aerial photograph, which includes a photographing date and time, a photographing altitude, a photographing latitude and longitude, an azimuth, and a magnification. 3 is a house map, 4
Is data related to a house map, which is longitude, latitude, azimuth, and scale. Reference numeral 5 denotes data relating to the position of the satellite, which is the altitude and longitude / latitude of the satellite. Reference numeral 6 denotes data on buildings, which is issued by a government agency or the like. Reference numeral 7 denotes sun position data, which is the position of the sun every hour throughout the year. 8 is a close-up camera,
9 is a data memory, 10 is an image frame memory, 1
1 is an image / data processing device, 12 is a satellite view map that visually displays the output of the process, and 13 is a database that is the output of the process.

The processing operation of the first embodiment will be described with reference to FIGS. FIG. 2 is a flowchart illustrating the processing operation of the first embodiment. FIG. 3 is a flowchart showing a program of the sun shadow extraction step 14, and FIG. 4 is an explanatory diagram of a determination operation for determining a sun shadow area in an image. FIG. 5 is a flowchart showing a program of a building height measuring operation 18, and FIG. 6 is an explanatory diagram of a sun shadow length calculating step 19.

In FIG. 1, first, aerial image data is stored in a frame memory 10 through a close-up camera 8. When the data is collected, a sun shadow extraction process (step 14), which is shown in detail in FIG. 3, starts. This step 14
Means a step of storing image data below a certain threshold value, that is, image data considered to be a sun shadow, in the frame memory as black pixels. Well this step 1
In FIG. 4, the RG of each pixel is read from the frame memory as shown in FIG.
B take each luminance value (step 24), calculates the RGB between luminance difference d _i (step 25), the RGB luminance between value difference is compared whether the following threshold T _h (step 26), T
_h or less pixels have the original RGB luminance value, otherwise the RGB values
Each luminance value is set to 1 (step 30). Further define the maximum value d _n of 3 luminance values of RGB for the pixels not one with each RGB luminance value (step 27), RG where d _n is shown in FIG. 4
It is checked whether it is smaller than the B maximum luminance value T _M (step 28). Then, for each pixel smaller than T _M, each of the RGB luminance values is set to 0 (step 29). This is sequentially scanned for the target area (step 31). As a result, a binary still image is generated that indicates a sun shadow area in which the sun shadow areas of all buildings in the target area are black pixels and the others are white pixels.

In FIG. 1, image data from the house map 3 is input through the close-up camera 8 and stored in the frame memory 10. Next, contour extraction is shown in the flowchart of FIG. 2. When the house map 3 is read from the frame memory 10, the contour of the bottom surface is extracted for each building (step 15), and the center of gravity of each building is extracted. Is calculated,
It is added to the image and stored in the frame memory 10. The house map 3 is read from the frame memory 10 again, and the road
Is extracted while maintaining its width and structure (Step 1)
6), stored in the frame memory 10. By this operation, the frame map 10 stores the house map 3, the building bottom contour diagram, and the road structure diagram.

Next, the sun shadow map generated in the above-described sun shadow extraction step (step 14) and the building bottom contour map are read from the frame memory 10. Then, the scale of the sun shadow map and two reference points are set based on the shooting altitude, shooting latitude and longitude, azimuth, and magnification of the aerial photograph data 2. Furthermore, house map data 4
Two points corresponding to the reference points set above are added to the building bottom contour diagram from the longitude and latitude values of. In order to make the scale of the sun shadow 41 figure and the building bottom contour diagram the same, each figure is enlarged or reduced to match both reference points (step 17), and the logical sum of the pixels in each figure is obtained by taking the logical sum of 1 in FIG. Two binary still images are created and stored in the frame memory 10. With this, the outline of the building and the shadow of the building are drawn on the same map, and the preparation for calculating the height of the next building is completed.

The building height measurement 18 is processed by using the sun shadow map, the photographing date and time of the aerial photograph data, and the sun position data. When these are input, a sun shadow length measurement step 19, which is shown in detail in FIG. 5, starts. In this step, first, the photographing date and time of the aerial photograph data 2 and the sun position data 7
From the aerial photograph at the time of aerial photography
Is calculated (step 32). Then, a straight line parallel to the sunlight traveling direction 43 is drawn through the center of gravity 40 of the building in FIG. 6 or from an arbitrary point (step 33), and the building bottom contour is drawn in the sunlight direction 43 along this straight line. The same figure 42 as 39 is moved (step 34), and the ratio of the number of black pixels present in this figure is calculated (step 35). The figure is moved until this ratio becomes equal to or less than the threshold (step 3).
6) The length of the sun shadow caused by the building is obtained from the moving distance A and the scale of the building sun shadow map (step 38).
This sun shadow length measuring step 19 is the output of the sun shadow length A
The height of the building is calculated geometrically from the sun position and altitude at the date and time of the aerial photography. Note that, when moving on a line drawn from a point other than the center of gravity 40, the accuracy of shadow detection is inferior.

Next, data indicating the bottom shape of each building is obtained from the output of the building height measurement 18 and the bottom view of the building, and the position, bottom shape and road of the building are obtained from the road map extracted from the house map 3. Then, a database 13 storing the adjacency relation is constructed (step 21). In this way, the data which can calculate which area will not reach the radio wave from the new satellite is prepared. The database 13 is constantly updated to the latest data by updating the existing building data 6 (building data issued by the public office, data in the blueprints) and inputting the latest aerial photograph and the changed portion based on the house map.

If the building data in the building database 13 is different from the data obtained by the building height measurement 18 in the present invention, the threshold values of the sun extraction step 14 and the sun shadow length measurement step 19 are changed and Is measured again, and the distribution of the difference from the value in the database 13 is obtained. For a building having an error based on this distribution, the data in the database 13 is assumed to be incorrect, and the data is updated.

From this building database 13, an urban building model is created which approximates the building to a prism based on the information of all the buildings in the target area, that is, the bottom, height and position of the building (step 22). . In this building model, roads are stored in a form having both width and structure data.

When the basic data is prepared in the database as described above, the calculation of the radio wave non-reachable area from the satellite at an arbitrary position is as follows. Satellite outlook mapping is based on the above building model and satellite position data 5,
The shadow generated by the building model when the light emitting source is placed at the apparent position of the satellite is geometrically calculated, and the shadow is displayed on the road map. It is considered that this shadow approximates an area where radio waves from the satellite have not reached (step 23). A map in which the radio wave unreachable area from the satellite, the bottom of the building, and the road are displayed in the same image is the satellite view map 12, and it is possible to determine whether or not the satellite has a view on all the roads in the map.

By creating the satellite view map 12 in the above-mentioned satellite radio wave non-reachable area calculation step, the satellite view map 12 can be created using the existing building database 6 by inputting the positions of different types of satellites. Can be created. Further, the data of the building database 13 can be updated not only by using the aerial photograph 1 and the house map 3 but also by using existing data.

In addition, 10G for which straightness of radio waves is not guaranteed
The display of the unreachable zone of the radio wave in the Hz band or less can be handled by inputting data that can calculate the reflection, attenuation, and diffraction of light into the building model.

Embodiment 2 FIG. In the above embodiment, the description has been given assuming that there is input of each luminance value of R, G, B as image data by aerial photograph.
The image data may be input in monochrome. In this case, there is no comparison of the respective color components in steps 24 and 25, and for example, the threshold value _Th
Will be set. Step 28 disappears,
In step 26, black (shadow portion) and white (sunlight portion) are determined on the basis of this.

Embodiment 3 FIG. In the above-described first embodiment, the building bottom contour line 39 is extracted from the house map 3, but the building bottom contour line 39 may use information for each building such as a design drawing. If building outline data can be directly input from these design drawings, the building bottom outline extraction step 15 is unnecessary.

Also, the sun shadow length measuring process (step 19)
Then, the sun shadow length is set to the same figure 42 as the building bottom contour 39.
As a simple method, the sun shadow length is calculated from the number of black pixels existing in the sunlight direction 43 from the center of gravity 40 on a straight line parallel to the sunlight direction 43 passing through the center of gravity 40 of the building bottom surface. It can also be calculated. In the first embodiment, when the position of the sun shadow map and the position of the building bottom contour map are made to match the scale, the reference point is set to 2 points and the scale is set to 3 points.
Points can be provided to make the two figures coincide.

In the above description, a case has been described in which the present invention is used for the satellite line-of-sight map creation 12.
It can also be used to calculate the radio wave propagation characteristics of terrestrial radio waves.
Needless to say, it can also be used for creating sunshine maps.

Embodiment 4 FIG. In the first embodiment, the invention has been described as a method including steps. However, instead of the sun shadow extraction or input step, a sun shadow extraction or image input means, instead of the building bottom contour extraction step, a building bottom contour input means, Instead of the shadow length measuring step, a sun shadow length measuring means, a building height calculating means instead of the building height calculating step, and hardware or equivalent means of a line-of-sight area calculating means may be used instead of the line-of-sight area calculating step.

[0027]

As described above, according to the present invention, a means for extracting or inputting a shadow portion of sunlight from image data such as an aerial photograph, a means for extracting or inputting a building bottom contour line, The means for calculating the length of the sun's shadow from both, the means for calculating the building height from it, and the means for calculating the line of sight from the satellite from these building heights are provided, making it easy to change the data, Any satellite position
There is an effect that the radio wave non-reachable area can be easily calculated from the height.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an embodiment of a satellite line-of-sight map creation method according to the present invention.

FIG. 2 is a flowchart showing the operation of a satellite line-of-sight map creation process according to the present invention.

FIG. 3 is a process of extracting a sun shadow according to the present invention (step 1);
It is a flowchart figure which shows the more detailed step of 4).

FIG. 4 is a diagram for explaining a threshold value and a reference value of a luminance value in a sun shadow extraction process according to the present invention.

FIG. 5 is a process (step 1) of measuring a sun shadow length according to the present invention;
It is a flowchart figure which shows the more detailed step of 9).

FIG. 6 is an explanatory diagram of a building height measuring process according to the present invention.

FIG. 7 is a block diagram showing a conventional satellite view map creation method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aerial photograph 3 House map 12 Satellite perspective map creation 14 Sun shadow extracting means 18 Building height measuring means 19 Sun shadow length measuring means 20 Building height calculating means 23 Satellite radio wave non-reachable area calculating means 39 Building bottom contour 41 Sun Shadow

Claims (2)

(57) [Claims] 1. A step of extracting or inputting a shadow portion of sunlight from image data from an aerial photograph or the like; a step of inputting a contour map of a building bottom from a house map or the like; Measuring the length of the shadow of sunlight from the portion and the outline of the building; calculating the height of the building from the length of the measured shadow of sunlight; and the height of the building obtained above. Calculating a line-of-sight area from a satellite from the data of the satellite, the contour map data of the bottom of the building and the input arbitrary satellite position / height data. 2. An image input means for extracting or inputting a shadow portion of sunlight from image data from an aerial photograph or the like; a contour input means for extracting or inputting a contour map of a building bottom from a house map or the like; Sun shadow length measuring means for measuring the length of the sunlight shadow from the shaded portion of the sunlight and the building contour map, and a building height for calculating the height of the building from the measured length of the sunlight shadow Calculating means for calculating a line-of-sight area from a satellite based on the height data of the building obtained above, the contour map data of the bottom of the building, and input arbitrary satellite position / height data; A satellite line-of-sight map creation method comprising an area calculation unit.