JP3467572B2 - Map creation method and device - 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 for creating a map based on remote sensing data such as satellite photographs and aerial photographs, and more particularly to a shading process as an advanced expression. In addition, in this specification, "map" refers to a diagram in which at least a part of the ground surface is scaled down and shown in a plane,
"Land use map" means a map to which information such as roads, place names, and boundaries is added.

[0002]

2. Description of the Related Art Conventionally, there is known a method of synthesizing remote sensing image data with a land use map and creating a map to which information such as terrain of remote sensing image data is added. In the synthesis, the remote sensing image data is subjected to image processing such as color correction, sharpening, contour enhancement, noise reduction and geometric correction.

[0003]

However, in the above-described conventional synthesizing method, since the shadows of the remote sensing image data are reflected directly on the synthesized map, the altitude representation of the synthesized map is unnatural and erroneous. It may give an impression.

That is, when the map is shaded, if the light is applied from the upper left side, it gives a natural impression to human vision, and it tends to easily recognize the unevenness due to the elevation difference from the shade. In the satellite image of the Northern Hemisphere, a shadow is created in the state that the light is shining from almost the south side. Therefore, when this is combined with a general map with the north facing up, the shadow looks like it is shining from the bottom side of the map, and it depends on altitude. The unevenness of the ground surface is reversed and is easily recognized.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and gives a shadow represented in a synthesized map independently of the shadow information included in the remote sensing image data. It is intended to provide a map creation method capable of performing.

[0006]

In order to achieve the above-mentioned object, a map creating method according to the present invention is based on a process of removing information related to a light source from remote sensing image data on the surface of the earth, and data on the landform. It is characterized by including a process of generating shadow data when light is applied from a predetermined direction, and a process of synthesizing the remote sensing image data that has undergone the luminance information removal process and the shadow data to generate map data. .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a map image synthesizing method according to the present invention will be described below. The map creation method of the embodiment removes at least pseudo information about a light source-related visual element, that is, information about a shadow, from remote sensing image data on the ground surface, and generates light source-related shadow data based on topographic data and elevation data. Then, this is combined with the remote sensing image data.

Since the information on the shades related to the light source is generated on the computer based on the altitude data, the terrain data, etc., it is possible to freely set the direction, the number, the brightness, etc. of the light sources. As a result, the shadow represented in the combined map can be added independently of the shadow information included in the remote sensing image data, and the following effects can be obtained.

1. It is possible to give a natural sense of unevenness to human vision even with a map on the north. It is possible to emphasize the unevenness of the terrain 3. Special expressions such as shading or modulation of output color depending on elevation are possible

[0010]

[Embodiment 1] FIG. 1 is an explanatory diagram of a map creating method according to a first embodiment. In the first embodiment, computerized satellite photographic data A ₀ as remote sensing image data and computerized altitude data B ₀ are input, and composite image data C ₀ is output through the following six steps. These steps are all executed on the computer in the first embodiment.

1. Geometric normalization 2. Signal linearization 3. Frequency distribution normalization 4. Luminance component removal 5. Shading image data generation 6. Synthesis

The satellite photograph data A ₀ and the altitude data B ₀ are
First, in the geometric normalization step, geometric conditions such as range / scale normalization, modification correction, and viewpoint correction are matched. The satellite photograph data A ₁ having the normalized RGB information is corrected in the signal linearization step so that the luminance of each color element of the satellite photograph is proportional to the incident light amount from the light source based on an appropriate interpolation formula or table. It

The linearly corrected satellite photograph data A ₂ and the normalized altitude data B ₁ have a visual frequency distribution of both data within a required range by a digital filter or a curved surface interpolation method in the frequency distribution normalization step. It is modified to increase the distinctiveness.

Luminance information is removed from the corrected satellite photograph data A ₃ by leaving the hue in the luminance component removing step, and is output as data A ₄ . The color data of the satellite photograph data A ₃ input in this step is A ₃ = (R, G,
B), the output satellite photograph data A ₄ is A ₄ = (f ₁ (A ₃ ), f ₂ (A ₃ ), f ₃ (A ₃ )) by the functions f ₁ , f ₂ and f _3. It is represented by. This removes the light source related information from the satellite photo data.

It should be noted that although the luminance component removal is executed in a single pixel unit or a plurality of pixel units on a computer, the luminance component removal step is performed in consideration of the information of the pixel to be processed or the pixels in the vicinity of the pixel group. It is also possible to add effects such as noise removal and adjustment of sharpness by executing.

On the other hand, in the shadow image data generating step, shadow data based on the three-dimensional topographic model is generated based on the corrected height data B ₂ . The shadow data is
The position, the number, the brightness, etc. of the light sources are arbitrarily set by the computer graphics method, and the calculation can be performed, and the expression such as the elevation enhancement can be added by the setting.

The satellite photograph data A ₄ as the hue information output from the luminance component removing step and the altitude data B ₃ as the luminance data output from the shadow image data generating step are combined in the combining step to obtain the image data C. ₀ is output on the screen or as a hard copy. The color information of the output C ₀ is given by the following expressions by the functions g ₁ , g ₂ and g ₃ .

[0018]

## EQU1 ## C ₀ = (g ₁ (A ₄ , B ₃ ), g ₂ (A ₄ , B ₃ ), g
₃ (A ₄ , B ₃ ))

By setting the function, it is possible to reproduce the hue of the unprocessed satellite photograph data A0 by changing only the brightness, but by combining RGB at an arbitrary ratio or extracting only one arbitrary color. It is also possible to output in a hue different from the unprocessed data. Also, the hue can be determined in consideration of the information of the neighboring pixels as in the case of the luminance component.

The composition is executed on the computer in this embodiment, but it is also possible to output the data A ₄ and B ₃ to a film or the like and optically compose them.

Further, as shown in FIG. 2, the output C _{0 of the} synthesizing step, the altitude data B ₂ output from the frequency normalizing step and the land use map data D are secondarily synthesized to obtain a stereoscopic image. By mapping C ₀ on the terrain model, combining it with the land use map data, and performing projection calculation,
It is also possible to generate land use map data C _{1 in} which the shadow data, the hue of the ground surface, and the topography are reflected.

The functions f _i , g _i used in the above steps
When (i = 1, 2, 3) , the function h is defined as follows, for example.

[0023]

F _i = (A ₃ ) _i / h (A ₃ ) g _i = (A ₄ ) _i · B ₃ h = √ ((A ₃ ) ₁ ² + (A ₃ ) ₂ ² + (A ₃ ) ₃ ² ) where (x) _i is the i-th component of x (i = 1, 2,
3)

Luminance information is removed by the function f _i , and hue and luminance are recombined by the function g _i. By appropriately selecting these functions, various special expressions and emphasized expressions are possible. For example, the brightness can be inverted by defining as follows. Also, depending on the settings,
It is also possible to make an expression in which the brightness information of the satellite photograph data A ₀ is left to some extent.

[0025]

## EQU3 ## g _i = (A ₄ ) _i (b-B ₃ ), b: constant

Further, in this embodiment, the hue is RGB3.
Since it is expressed by a component, when a plurality of light sources is set and shadow data is generated, different functions g _i are prepared for each light source, and these functions are added together, so that it is possible to illuminate a plurality of light sources. It is also possible to make various expressions.

The remote sensing image data processed in the first embodiment may be any ground surface reflected light measurement data that includes two or more components that are both related to the amount of incident light and independent of each other. In addition to satellite and aerial photographs by
It may be an image obtained by electromagnetic waves such as infrared rays,
The information regarding the hue is not limited to the information about the three colors of RGB.

[0028]

Second Embodiment FIG. 3 shows a second embodiment of the map creating method of the present invention. The computerized satellite photograph data A ₀ as the remote sensing image data and the computerized altitude data B ₀ are input, and the composite image data C ₀ is output through the following four steps. These steps are all executed on the computer in the second embodiment as well.

The satellite photograph data A ₀ input as remote sensing image data in the second embodiment is
It may be multi-component data as in the first embodiment, or may be monochrome single-component data.

1. Global fluctuation elimination 2. Fine fluctuation removal 3. Shading data generation 4. Synthesis

The global fluctuation component is removed from the satellite photograph data A ₀ in a global fluctuation elimination step (filter).
Here, the minute fluctuations in the satellite image data are regarded as data independent from the light source, and the global fluctuation component is regarded as information related to the light source and removed.

The altitude data B ₀ is the fine fluctuation removing step.
Fine fluctuation components are removed in the (filter). This step is not indispensable for the second embodiment, and since the minute fluctuation component of the satellite photograph data is reflected after being combined, if the minute fluctuation component of the altitude data B0 overlaps this component, that component is necessary within the predetermined area. It is removed according to.

The altitude data B ₁ from which the minute fluctuations are removed is
In the shading data generation step, the shading data is processed by a three-dimensional terrain model. The shadow data is calculated by a computer graphics method by arbitrarily setting the position, number and brightness of light sources.

The satellite photograph data A ₁ from which the minute fluctuation component has been removed and the altitude data B ₂ as shadow data are combined in the combining step, and the image data C ₀ is output on the screen or as a hard copy.

In the synthesizing step, the output can be obtained by C ₀ = f (A ₁ , B ₂ ) using the function f.
For example, the function f may be set to f (x, y) = x + y.
Further, it is possible to prepare a plurality of functions to obtain a color output, and it is also possible to combine the output C ₀ with the data of the three-dimensional terrain model or the land use map based on the altitude data B ₁ as in the first embodiment. .

The steps of removing the global fluctuation and removing the minute fluctuation can be executed by using a filter by a thinning method or a curved surface interpolation method, a difference / summation filter, a digital filter or the like.

In the method of the second embodiment, the information regarding the light source is artificially removed from the satellite photograph data by regarding the global fluctuation as the information regarding the light source. The present invention can be applied to a multi-component image for the same purpose as 1 or a mono-component monochrome image.

[0038]

As described above, according to the present invention, it is possible to synthesize a shadow in a state where light is applied from a desired direction without being influenced by information related to a light source included in remote sensing image data. You can create a map.

Therefore, for example, when synthesizing a satellite image in the northern hemisphere as a map with the north facing up, it is possible to shade the upper left side to give a natural impression to human vision. It is possible to provide a map in which it is easy to recognize the unevenness due to the elevation difference from the shadow.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a map creating method according to a first embodiment.

FIG. 2 is a block diagram showing additional steps of the map creating method according to the first embodiment.

FIG. 3 is a block diagram illustrating a map creating method according to a second embodiment.

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Claims (10)

(57) [Claims] 1. Remote sensing image data of the surface
A = (A1, A2, ..., An) (n is an integer of 2 or more)
Remote sensing without shading information related to the light source
Image data A '= (A1', A2 ', ..., An') is calculated.
Calculation process and a predetermined set arbitrarily based on the terrain data
Process of generating shadow data B when light is applied from the direction
And a remote sensor that removes shading information related to the light source.
The shadow data B for each component of the ringing image data A '.
The process of synthesizing and generating map data is included.
How to create a map. _{However, Ai '= f i (Ai} , h (A1, A2, ..., A
n)) (i = 1, 2, ..., N) 2. Correcting the remote sensing image data
To normalize and normalize the terrain data
Mapping method according to claim 1, wherein the. 3. A process of removing information related to a light source from remote sensing image data of the ground surface, and a process of generating shadow data when light is applied from a predetermined direction arbitrarily set based on the topographical data. And the above removal
And a process of generating a map data by combining the remote sensing image data and the shading data through the degree, in the removal process, by removing the filter global fluctuation component of the remote sensing image data, wherein A method of creating a map, characterized in that brightness information of remote sensing image data is artificially removed. 4. The removal of the global variation component is executed by using any one of a filter by a thinning method, a filter by a curved surface interpolation method, a difference / summation filter, and a digital filter.
Map creation method described in. 5. The map creating method according to claim 1, wherein a land use map is synthesized in addition to the synthesis of the remote sensing image data and the shadow data. 6. The map creating method according to claim 1, wherein in addition to combining the remote sensing image data and the shadow data, data regarding the landform is combined. 7. The remote sensing image data of the ground surface
A = (A1, A2, ..., An) (n is an integer of 2 or more)
Remote sensing without shading information related to the light source
Image data A '= (A1', A2 ', ..., An') is calculated.
A means to calculate and a predetermined set arbitrarily based on the terrain data
Means for generating shadow data B when light is applied from the direction
And a remote sensor that removes shading information related to the light source.
The shadow data B for each component of the ringing image data A '.
A computer that synthesizes and generates map data
A map making device characterized by being executed on the above. _{However, Ai '= f i (Ai} , h (A1, A2, ..., A
n) (i = 1, 2, ..., N) 8. A means for removing information related to a light source from remote sensing image data on the surface of the earth, and a means for generating shadow data when light is applied from a predetermined direction arbitrarily set based on the terrain data. And the removal hand
A means for synthesizing the remote sensing image data having passed through the steps and the shadow data to generate map data is executed on a computer, and the removing means removes a global variation component of the remote sensing image data by a filter. By so doing, the brightness information of the remote sensing image data is artificially removed. 9. Remote sensing image data of the ground surface
A = (A1, A2, ..., An) (n is an integer of 2 or more)
Remote sensing without shading information related to the light source
Image data A '= (A1', A2 ', ..., An') is calculated.
Calculation process and a predetermined set arbitrarily based on the terrain data
Process of generating shadow data B when light is applied from the direction
And a remote sensor that removes shading information related to the light source.
The shadow data B for each component of the ringing image data A '.
The process of synthesizing and generating map data is included.
How to create a map image to collect. _{However, Ai '= f i (Ai} , h (A1, A2, ..., A
n)) (i = 1, 2, ..., N) 10. Ground remote sensing image data
The process of removing light source related information from the
Light from a predetermined direction that is arbitrarily set based on the data
The process of generating shadow data when applying
The remote sensing image data and the shadow
A process of synthesizing shadow data with map data to generate map data.
In the removal process, the remote sensing image data
To remove the global fluctuation component of the data with a filter
Therefore, the brightness information of the remote sensing image data
Map image creation method characterized by pseudo removal
Law.