JP2011133952A - Producing method of transparent color shaded relief map, producing program, and transparent color shaded relief map - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a producing method of a transparent color shaded relief map, a producing program, and a transparent color shaded relief map, for making an altitude tints map and a shaded relief map perform transparent display after being overlapped so that whole brightness is raised, and for easily grasping a topography depending on directionality such as a fault etc. <P>SOLUTION: The transparent color shaded relief map for making the altitude tints map and the shaded relief map to be transparent-displayed after being overlapped relating to the same terrain model is provided wherein the terrain model is a DEM to be produced from point group data, and the altitude tints map makes each pixel to be tint displayed by an RGB value corresponding to an altitude value of a pixel based on a color table in which the RGB value corresponding to the altitude value is set, while the shaded relief map makes each pixel to be displayed by a gray scale corresponding to a shading degree of the pixel based on a gray scale table in which the gray scale corresponding to the altitude value is set. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a color shading diagram in which an elevation step chromatic diagram and a shadow diagram are displayed in an overlapping manner, and more specifically, relates to a transparent color shading diagram that is displayed through the laid elevation level chromaticity diagram and the shadow diagram. is there.

  Japan is known as a country where earthquakes occur frequently. In recent years, large earthquakes such as the Hyogoken-Nanbu Earthquake and the Niigata Chuetsu Earthquake have occurred, and each time they are suffering enormous damage. The main cause of the earthquake is considered to be active faults, the Nojima Fault in the 1995 Hyogo-ken Nanbu Earthquake, the Kohirao Fault in the 2003 Miyagi Northern Earthquake, and the Sue in the 2004 Niigata Chuetsu Earthquake. Faults are the cause of each.

  It is said that there are about 2000 active faults in the land area of Japan, but the positions of all active faults are not clear, and now earnest investigations by various organizations including the Ministry of Education, Culture, Sports, Science and Technology. Is underway. Active fault survey methods include local surveys such as topographic observation, surveying, trench surveys, and geophysical surveys such as elastic wave exploration, and desktop surveys such as interpretation of aerial photographs. We grasp the existence of active faults, and then conduct field surveys on specific active faults.

  Conventionally, the interpretation of aerial photographs, which has been performed as a desktop survey, aligns two aerial photographs taken of the terrain with an aircraft or the like, and reads the undulations of the terrain when a person stereoscopically views to grasp the existence of an active fault. Is. This aerial photo interpretation requires skill, so it cannot be performed by anyone, and it is extremely difficult to show a stereoscopic image to others.

On the other hand, measurement techniques for acquiring terrain information, such as the emergence of aerial laser measurements, have been remarkably advanced, and the technology for handling terrain information has progressed dramatically with the evolution of computers. As shown in FIG. 11, the aviation laser measurement is performed by flying the aircraft B over the terrain A to be measured and receiving the reflection of the laser C irradiated on the terrain A during the flight. According to this aerial laser measurement, countless point cloud data can be densely acquired as information representing the terrain, and if this point cloud data is processed by a computer, the measured terrain can be modeled. In this way, the terrain model modeled on a computer can be expressed in three dimensions. Recently, it has been adopted in a wide range of fields as a method to reproduce terrain, not only as a desktop survey instead of aerial photo interpretation. Yes.

As a technique for representing the terrain three-dimensionally, for example, in Patent Document 1 filed by the applicant prior to the present application, a DEM is created from point cloud data acquired by aviation laser measurement, and an inclination amount or an altitude value is applied to each mesh of the DEM. A color elevation map (also called “elevation stage chromatic chart”) or a grayscale slope map is created based on the topographic volume, and a color elevation map that combines this color elevation map and the grayscale slope map. We have proposed a system for creating a slope map.

JP2007-48185

The color elevation slope map of Patent Document 1 displays the slope in shades so that anyone can see the topography in three dimensions, and the elevation is displayed in different colors so that the topography can be easily grasped. Can do. In addition, the terrain can be comprehended equally at any point because it does not shade the terrain by shining light from a specific direction, such as a shadow map. However, when a terrain (hereinafter referred to as “direction-dependent terrain”) that is easy to grasp by applying light from a predetermined direction and shadowing the terrain, such as a fault, is the target. However, there is a problem that it is difficult to grasp the fine terrain because the color elevation slope map does not depend on the directionality.

As in Patent Document 1, a figure that can grasp the topography equally at any point, that is, a drawing that does not depend on directionality is currently widely used, but a drawing that depends on directionality, for example, an altitude step color chart and a shaded figure The color shading figure which synthesized was sometimes used. Elevation stage chromatic maps are color-coded according to the altitude, and shade maps shade light from a specific direction to shade the terrain and display the shade in shades. This shading map is a figure that depends on directionality, that is, a fine terrain is emphasized by light and shade for a certain direction, but it is difficult to grasp the terrain for a certain direction. The color shading that combines the shading and shading is also direction dependent.

A color shading map should be able to clearly grasp the topography that depends on the directionality, such as a fault, if light is applied from a predetermined direction, but the conventional color shading map becomes dark overall, so such topography It was extremely difficult to grasp. In particular, when other thematic maps (for example, topographic maps) and conventional color shading maps are superimposed, the micro topography such as faults may even be erased. This is because the RGB values of the elevation stage chromatic diagram and the RGB values of the shaded diagram are multiplied and synthesized. As shown in the following equation, the brightness is generally lowered in the multiplication and synthesis, and as a result, the entire image is dark.
(RGB in elevation chart) x (RGB in shadow map) / 255
As described above, the conventional color shading map has a problem that it is difficult to grasp the topography depending on the directionality such as a fault although it is a figure depending on the directionality.

The subject of the present invention is a transparent color that solves the above-mentioned problems and allows the elevation chromatic diagram and shadow map to be transparently displayed so as to increase the overall brightness, and to easily grasp the topography depending on the directionality such as a fault. The object is to provide a method and program for creating a shadow map, and a transparent color shadow map.

The method of creating a transparent color shading map of the present invention is to create an altitude step chart that colors with the color according to the altitude value for the same topographic model, and shade the light from the light source placed at a predetermined position. A step of creating a shadow map, and a step of transparently displaying the altitude step color chart and the shadow map in a superimposed manner.

In this case, the terrain model is a DEM, a step of creating a pixel based on the mesh of the DEM, a step of assigning an altitude value to each pixel, and a pixel with respect to an incident angle of light to each of the pixels. A step of assigning a shade degree calculated based on the inclination, a step of creating a color table in which RGB values corresponding to elevation values are set, and a step of creating a gray scale table in which a gray scale corresponding to the shade degree is set A step of coloring each pixel with an RGB value corresponding to the altitude value of the pixel based on the color table to create an altitude step chart, and a gray level corresponding to the shading level of the pixel based on the gray scale table. And displaying each pixel on a scale to create a shadow map. Further, the step of transparently displaying the elevation step color chart and the shadow diagram in a superimposed manner may be a step of displaying the RGB values of the elevation step color illustration and the gray scale of the shadow drawing by translucent synthesis for each pixel.

The transmission color shading diagram creation program according to the present invention has a function of assigning an altitude value to a pixel created based on each mesh of the DEM, and the pixel's incident angle of light from a light source placed at a predetermined position. Color each pixel with an RGB value according to the altitude value of the pixel based on the color table that sets the RGB value corresponding to the altitude value and a function that calculates the shading level based on the inclination and gives the shading level to the pixel. A function to display and create an elevation chart, and a function to create a shade map by displaying each pixel in gray scale according to the shade of the pixel based on a gray scale table with a gray scale corresponding to the shade degree And the function of displaying the elevation map and the shadow map in a transparent manner on the same terrain model composed of DEM. Those which are capable of running relative data. In this case, the function of transparently displaying the altitude step color chart and the shadow map in a superimposed manner can be a function of displaying the RGB value of the altitude step color map and the gray scale of the shadow map in a translucent manner for each pixel.

The transmission color shading diagram of the present invention is an altitude stage coloring diagram that colors with the color according to the altitude value for the same terrain model, and a shading diagram that shades the light from the light source placed at a predetermined position, The terrain model is a DEM, and the pixel created based on the mesh of the DEM is calculated from the altitude value and the inclination of the pixel with respect to the incident angle of light. The elevation stage coloring chart is a color display of each pixel with an RGB value corresponding to the elevation value of the pixel, based on a color table in which the RGB value corresponding to the elevation value is set. The shading diagram displays each pixel in a gray scale corresponding to the shading degree of the pixel based on a gray scale table in which a gray scale corresponding to the shading degree is set. . In this case, for each pixel, the RGB values of the elevation stage chromatic diagram and the gray scale of the shadow diagram may be translucently displayed by being translucently combined. Further, the elevation stage chromatic chart, the shadow map, and the contour map may be superimposed and transparently displayed.

The transmission color shade drawing creation method and creation program and the transmission color shade drawing of the present invention have the following effects.
(1) Since there is a shadow map, there is direction dependency, and as a result, it is possible to clearly grasp the topography depending on the directionality such as a fault.
(2) Since the altitude step color chart and the shadow map are displayed in a transparent manner, the shadowed portion and the fine topography can be easily grasped as compared with the conventional color shadow map.
(3) Since the brightness of the entire figure is high, it is possible to grasp the topography that depends on the directionality such as a fault even if it is superimposed on another theme map such as a topographic map.
(4) Since the fine topography can be confirmed even in the shaded part, error detection (excessive data stripping or leaving of data to be removed) becomes easy.

Explanatory drawing for demonstrating the transmission color shade figure of this invention. FIG. 10 is a flow chart for creating a transmission color shading diagram of the present invention in comparison with a conventional color shading diagram. Explanatory drawing which modeled three attributes of color. (A) is explanatory drawing which shows the collection of the laser measurement point measured at random, (b) is explanatory drawing which shows the state which covered the square lattice on the laser measurement point. Explanatory drawing which shows an example of the method of setting the range of an altitude value when producing a color table. Explanatory drawing for demonstrating an altitude step color chart. Explanatory drawing for demonstrating a shadow figure. (A) is explanatory drawing which shows the concept which the light from a light source shades the mesh of a terrain model, (b) is the light from the light source placed in the position different from (a) shades the mesh of a terrain model Explanatory drawing which shows a concept. (A) is explanatory drawing which shows the concept by which a mesh is inclinedly arranged by coordinate shape, (b) is explanatory drawing which shows the azimuth of a mesh, (c) is explanatory drawing which shows the vertical angle of a mesh. (A) is a transmission color shading diagram when the light source is arranged so that the light source vertical angle is 65 degrees and the light source azimuth angle is 315 degrees, and (b) is a light source vertical angle of 65 degrees and a light source azimuth angle of 45 degrees. The transmission color shading figure when arranging a light source so that it may become. Explanatory drawing which shows the acquisition condition of the point cloud data by aeronautical laser measurement.

(Embodiment)
An embodiment of a method and program for creating a transmission color shading diagram and a transmission color shading diagram of the present invention will be described with reference to the drawings. FIG. 1 is a transparent color shading diagram 1 in which an elevation level chromatic diagram and a shading diagram are superimposed and displayed. As can be seen from FIG. 1, the transparent color shading FIG. 1 is a diagram that is bright overall (high in brightness) and can easily grasp the fine features of the terrain.

(Overview)
FIG. 2 is a flowchart showing the creation flow of the transparent color shading diagram 1 according to the present invention in contrast to the conventional color shading drawing creation flow. As shown in FIG. 2, both the transmission color shading diagram 1 of the present invention and the conventional color shading diagram are a set of points having plane coordinates (X, Y) and altitude values (Z) of the ground surface by aviation laser measurement or the like. So-called point cloud data is acquired, a DEM is created from the point cloud data, and an elevation stage color chart and a shadow map are created from the DEM. The difference between the creation of the transmission color shading diagram 1 of the present invention and the conventional color shading drawing is in the step of synthesizing the elevation color chart and the shading diagram. In contrast to the transparent display of the figure, in the creation of a conventional color shading diagram, the RGB of the elevation chart and the RGB of the shading diagram are multiplied and synthesized. Due to the difference in the synthesizing means, as shown in FIG. 2, the transmission color shading diagram 1 of the present invention is generally brighter than the conventional color shading diagram.

In the following, detailed description will be given of elevation charts, shading diagrams, and transmissive displays. Before that, some basic techniques necessary for explaining these technical contents will be described.

(Three attributes of color)
Originally, colors are recognized by human vision and are accompanied by individual differences. In recent years, this color has been modeled to be handled by computers (electric calculators). There are various methods for modeling colors, and RGB, Cyan, Magenta, Yellow, and Yellow, which are the basic colors of red, green, and blue. CMYK having four basic colors of black (Keycolor), NCS and Ostwald color system having six basic colors of yellow, red, blue, green, black, and white are known. In the present embodiment, a case where colors are modeled by RGB will be described. However, other methods may be adopted to implement the present invention.

A color has three attributes including hue, saturation, and brightness. As described above, RGB uses red, green, and blue as basic colors, and various colors are expressed by additive color mixing of these three primary colors, and hue, saturation, and brightness are expressed by various combinations. Specifically, RGB expresses red, green, and blue with respective lightness values. If red lightness is r, green lightness is g, and blue lightness is b, RGB is (r, g, The three attributes of the color are expressed by a combination of the values of r, g, and b. The brightness is often expressed as an integer from 0 to 255, but may be expressed in a range of 0% to 100%, expressed in a range of 0 to 1 (not limited to an integer), or appropriately selected. it can. As an example, the pure red RGB is represented by (255, 0, 0), the pure green is (0, 255, 0), and the pure blue is (0, 0, 255).

The expression of hue, saturation, and brightness by RGB will be described with reference to FIG. FIG. 3 is an explanatory diagram modeling the three attributes of color, and the spherical shape in this figure indicates a combination of hue, saturation, and brightness that can be expressed in RGB.

The hue represents the color and changes from red to green to blue in the direction of arrow H around the central axis O shown in FIG. In addition, there is yellow (255, 255, 0) that mixes these between red and green, and there is also a color that mixes these between green and blue, and between blue and red, and the hue gradually increases. Will change. In addition, what expressed the change of only the hue on the plane is called a hue ring.

Saturation literally represents the vividness of the color, and the color becomes more vivid as it moves away from the central axis O shown in FIG. Pure red (255, 0, 0), pure green (0, 255, 0), and pure blue (0, 0, 255) are on the circumference farthest from the central axis O (on the spherical equator). There is maximum saturation. On the other hand, when the values of red lightness r, green lightness g, and blue lightness b are approximated such that RGB is (255, 200, 200), etc., the respective lightness values are offset and approach the central axis O, that is, the color. The degree becomes smaller (in this case, it becomes whitish). When the lightness r of red, the lightness g of green, and the lightness b of blue are all equal, they are located on the central axis O, and the saturation is lost and the hue is eliminated. As a result, the color expressed only by the lightness It becomes. For example, when RGB is (255, 255, 255), it is white, and when RGB is (0, 0, 0), it is black.

The lightness represents the brightness (darkness) of the color, and the color becomes brighter as it goes in the direction of the arrow Lu parallel to the central axis O shown in FIG. 3, and the color becomes darker as it goes in the direction of the arrow Ld. That is, white (255, 255, 255) having the maximum lightness of all of the lightness of red, green lightness g, and blue lightness b is brightest, and conversely, red lightness r, green lightness g, and blue lightness b. Black (0, 0, 0), which has the minimum brightness b, is the darkest color. The pure red color (255, 0, 0) has the maximum lightness except for the lightness value r of red, and the maximum lightness is obtained. As it goes, it approaches the lowest point of the sphere in the figure (spherical south pole), and not only does the lightness decrease, but the saturation also decreases and the hue is lost.

(grayscale)
The gray scale represents a color only by lightness among the three attributes of color (there is no hue or saturation, but because it has lightness, the gray scale is also expressed as “color” here). The range on the line of the central axis O is expressed. In RGB, when all values of the lightness r of red, the lightness g of green, and the lightness b of blue are equal and the lightness is expressed by an integer from 0 to 255, (0, 0, 0) to (255, 255, 255) ) 256 types of colors can be expressed.

In the present application, a gray scale is used for a shadow diagram described later. In this application, it is of course possible to use a strict gray scale (hereinafter referred to as “strict greyscale”) in which all values of the lightness r of red, the lightness g of green, and the lightness b of blue are equal. Although the values of r, green lightness g, and blue lightness b are slightly different, even a color in a range that visually appears white, gray, and black (hereinafter referred to as “approximate gray scale”) is shown in the shaded view. Can be used. In addition, even a gray scale by other methods such as a monochrome gray scale can be used for a shadow diagram. That is, a strict gray scale, a combination of a strict gray scale and an approximate gray scale, or a gray scale obtained by another method such as monochrome can be used for a shadow diagram.

(DEM)
DEM is an abbreviation of Digital Elevation Model, and is a numerical model of the terrain that is the shape of the ground surface, and is generally a lattice model. In this embodiment, the case where the DEM is adopted as the terrain model is described, but another terrain model may be adopted. The DEM is formed based on so-called point cloud data, which is a set of points having the plane coordinates (X, Y) and elevation value (Z) on the ground surface. The denser the point cloud data, the more accurately the original terrain is reproduced. can do. This point cloud data can be acquired by aviation laser measurement. As shown in FIG. 11, the aviation laser measurement is performed by flying the aircraft B over the terrain A to be measured and receiving the reflection of the laser C irradiated on the terrain A during the flight. When acquiring point cloud data by this aerial laser measurement, it is desirable to perform so-called filtering processing that removes data that is not the ground surface, such as the top of a tree, to obtain more accurate point cloud data on the ground surface. Point cloud data can be acquired by aerial laser measurement that can acquire a large amount of measurement data over a wide range, or point cloud data with three-dimensional spatial information may be generated based on stereo aerial photographs and satellite photographs. Alternatively, point cloud data having three-dimensional spatial information may be acquired by directly surveying the site. In any case, the acquisition method is not limited as long as it is point cloud data having three-dimensional spatial information.

The point cloud data acquired by aviation laser measurement is a set of laser measurement points 2 randomly measured as shown in FIG. 4A, and a DEM is created by the following procedure. That is, as shown in FIG. 4 (b), a plurality of grids (axes) arranged at intervals of 2 m, that is, a square lattice in which the horizontal axis 3 and the vertical axis 4 intersect with each other, are obtained. Put on. By being divided by this square lattice, lattice points 5 are generated, and a large number of squares, that is, meshes 6 are formed. One representative point 7 is provided on the mesh 6, and the point provided at the center of the mesh 6 will be described as the representative point 7 here. The representative point 7 is provided at the lattice point 5 such as the lattice point 5 at the upper right corner of the four lattice points 5, the representative point 7 is provided at an arbitrary position in the mesh 6, etc. It goes without saying that various selections can be made. In the present embodiment, creation of a DEM will be described using an example of a square lattice having a horizontal axis 3 and a vertical axis 4 orthogonal to each other. However, if the plane coordinates (X, Y) of the lattice point 5 can be specified, A grid in which the axes 4 are not orthogonal or any other grid can be adopted.

Based on the three-dimensional spatial information (X, Y, Z) of the laser measurement point 2, the plane coordinates (X, Y) and the altitude value (Z) of the representative point 7 are calculated. This calculation method includes an interpolation method by TIN (Triangulated Irregular Network) for obtaining the height from the irregular triangulation from the laser measurement point 2, a nearest neighbor method (Nearest Neibor) employing the nearest laser measurement point 2, and the inverse Conventional methods such as a distance weighting method (IWD), a Kriging method, and an averaging method can be employed.

In addition, a drawing pixel 6 a is created based on the mesh 6. In this embodiment, the mesh 6 (2m × 2m), which is the minimum unit of the lattice network shown in FIG. 4B, is defined as one pixel 6a (2m × 2m), and the representative point 7 of the mesh 6 is the representative of the pixel 6a. This will be described as point 7. In order to change the pixel size, the size of the DEM mesh (that is, the grid interval) may be adjusted. Alternatively, a plurality of meshes 6 can be a single pixel, such as four meshes 6 being a single pixel 6b (4 m × 4 m). If a plurality of meshes 6, for example, four meshes 6, are used as one pixel 6 b, the representative points 7 are also four. In this case, of the four representative points 7, the one with the highest elevation value or the lowest one, Or the thing close | similar to an average value can also be made into the representative point 7 of the pixel 6b, and you may provide the representative point 7 in the center of the four meshes 6 newly.

(Standing chart)
The elevation stage chromatic diagram 8 shown in FIG. 6 is a diagram arranged based on the Z value of the three-dimensional spatial information (X, Y, Z), that is, the elevation value. A color table in which elevation values and RGB values are associated with each other is created in advance, the elevation value of the representative point 7 of the pixel 6a is compared with the color table to determine the RBG value, and the RGB value is used to color the pixel 6a. To do. When this is performed for all the pixels 6a included in the drawing range, an elevation stage chroma chart 8 is created.

In creating the color table, the altitude value has a predetermined range, and the RGB value is associated with each range. Further, the RGB values may correspond in the entire range (the entire sphere in FIG. 3), or may correspond only in the hue on the spherical equator in FIG. 3, that is, in the range of the color having the maximum saturation. Also good. As an example, a color table can be created with an altitude of 0 to 20 m in blue and an altitude of 100 to 120 m in red.

Further, as shown in FIG. 5, since the point group of the laser measurement point 2 usually shows a normal distribution, the altitude is set so that the area surrounded by the graph indicated by the probability density function and the X axis (elevation value axis) is equal to each other. A range of values may be defined. As an example, in the drawing, the areas 1 to 7 are divided into seven ranges including the ranges 1 to 7 so that the areas 1 to 7 are equal to each other. A RGB table corresponding to each of these seven ranges is set to create a color table. Of course, the color table may be created with a larger number of ranges.

(Shaded figure)
The shaded figure 9 shown in FIG. 7 is a diagram expressing how the topographic model shades sunlight. Actually, as shown in FIGS. 8A and 8B, it is assumed that the light source 10 is placed at a predetermined position instead of sunlight, and a shadow is added based on the light from the light source 10 toward each mesh 6. Yes. Therefore, the shaded figure 9 can be created by shining light from a position that is not actually on the orbit of the sun.

The direction of light emitted from the light source 10 placed at a predetermined altitude and a predetermined plane position has a planar angle and an angle formed with a vertical plane (hereinafter referred to as “light source vertical angle”). Here, the planar angle is an angle from north (X-axis in the survey coordinate system), and this angle is called a light source azimuth.

Each mesh 6 is also inclined with an azimuth angle and a vertical angle, and similarly, the pixels 6a formed from the mesh 6 are also inclined. Note that the amount of inclination indicating the degree of inclination of the pixel 6a is calculated based on the representative point 7 of the pixel 6a and the coordinate values (X, Y, Z) of the representative point 7 of the surrounding pixels 6a. In this case, it is also possible to calculate using the laser measurement points 2 located around.

The inclination of the pixel 6a represented by the calculated inclination can be conceptually shown in FIG. A pixel 6a shown in this figure is represented as a plane S in a coordinate system composed of an X axis, a Y axis, and a Z axis. Here, the explanation is given in the survey coordinate system in which the X-axis faces north. The surface S is expressed by the following expression in this coordinate system.
aX + bY + cZ + d = 0 (where a, b, c and d are constants)
When a straight line formed when the surface S intersects the horizontal plane is a straight line L1, and a straight line perpendicular to the straight line L1 and on the surface S is a straight line L2, the angle formed by the straight line L1 and the X axis is an azimuth angle δ. (FIG. 9B), the angle formed by the straight line L2 and the XZ plane is the vertical angle θ (FIG. 9C). Since the straight line L1 is Z = 0, it can be expressed by the following equation.
aX + bY + d = 0
Accordingly, the azimuth angle δ is expressed by the following equation.
δ = tan ⁻¹ [−a / b]
The vertical angle θ is expressed by the following equation.
θ = tan ⁻¹ [−c / (a ² + b ² ) ^1/2 ]

Based on the azimuth angle δ and vertical angle θ of the pixel 6a calculated in this way, and the light source azimuth angle and light source vertical angle of the light from the light source 10, the shading degree, which is a parameter representing the degree of shading, is set for each. Calculation is performed on the pixel 6a. Calculated from the azimuth angle δ and vertical angle θ of the pixel 6a, the light source azimuth angle and the light source vertical angle of the light, and when the surface side of the pixel 6a is perpendicular to the light, the shading degree (hereinafter, “ It is called “bright shade”. On the contrary, when the back side of the mesh 6 is perpendicular to the light, a shading degree (hereinafter referred to as “dark shading degree”) that gives the most shadow is given.

As an example, a straight line (hereinafter referred to as “normal line”) extending in a direction perpendicular to the pixel 6a surface S is calculated by the following equation, and an angle at which the normal line and the light from the light source 10 intersect is obtained. The longer the cosine length is (the smaller the cosine angle is), the brighter shade is given, and the shorter the cosine length (the larger the cosine angle is), the darker shade is given.
(X−X ₀ ) / a = (Y−Y ₀ ) / b = (Z−Z ₀ ) / c
However, (X ₀ , Y ₀ , Z ₀ ) is a point on the pixel 6a surface S.

In order to give a gray scale according to the shade degree, a gray scale table in which the shade degree is associated with the gray scale is created. In this case, a gray scale with a high lightness is made to correspond to a bright shade, and a gray scale with a low lightness is made to correspond to a dark shade. Specifically, the gray scale table is created such that the brighter the shade is, the closer RGB is to white (255, 255, 255), and the darker the shade is, the closer RGB is to black (0, 0, 0).

A gray scale (RBG value) is determined by comparing the shade degree calculated in each pixel 6a with a color table, and the color is arranged with respect to the pixel 6a with the gray scale (RBG value). When this is performed for all the pixels 6a included in the drawing range, a shadow diagram 9 is created.

(Transparent display)
When two different types of maps are created for the same terrain model and are combined, conventionally, RGB values are multiplied and combined. Multiply synthesis is a value obtained by multiplying red lightness r, green lightness g, and blue lightness b, which are two different RGB values (lightness), respectively, and dividing them by the maximum value of lightness, as shown in the following equation: Is the RGB value after synthesis.
_{(R 3, g 3, b} 3) = (r 1 × r 2/255, r 1 × r 2/255, r 1 × r 2/255)
Note that (r ₁ , g ₁ , b ₁ ) and (r ₂ , g ₂ , b ₂ ) are RGB values in different diagrams before synthesis, and (r ₃ , g ₃ , b ₃ ) is after synthesis RGB value.
As described above, in multiplication synthesis, each RGB value (brightness) after synthesis tends to be small, that is, the figure after multiplication synthesis tends to be dark.

In the present invention, for the same terrain model (DEM), the altitude stage chromatic diagram 8 and the shaded map 9 are created, and these are superimposed and transmissively displayed to create the transmissive color shaded figure 1, which is transmissively displayed. As a result, the brightness of the transparent color shading 1 is increased (displayed brightly), and the fine terrain can be easily grasped. This transmissive display will be described below.

In the transmissive display, the RGB value of the elevation chart 8 in the pixel 6a and the gray scale (RGB value) of the shaded map 9 in the pixel 6a are expressed by the following equation for the same pixel 6a of the same terrain model (DEM). Synthesize.
r _t = r _h × α + r _i × β
g _t = g _h × α + g _i × β
b _t = b _h × α + b _i × β
Note that (r _h , g _h , b _h ) are the RGB values in the elevation chart 8, (r _i , g _i , b _i ) are the RGB values in the shadow diagram 9, and (r _t , g _t , b _t ) are the synthesis. The RGB values, α and β in the later transmission color shading FIG. 1 are the transmission coefficients of the elevation stage chroma 8 and shading 9, respectively. In this way, the brightness value is increased by adding the RGB value of the elevation stage chromatic diagram 8 and the RGB value of the shaded figure 9 instead of multiplication, and both the RGB value of the elevation stage chromatic figure 8 and the RGB value of the shaded figure 9 are multiplied by the coefficients. Both figures are transparent. Note that a synthesis method in which the sum of the transmission coefficient α in the elevation stage chromatic diagram 8 and the transmission coefficient β in the shaded drawing 9 is 1 and is synthesized by the following equation is referred to as translucent synthesis.
r _t = r _h × (1−β) + r _i × β
g _t = g _h × (1−β) + g _i × β
b _t = b _h × (1−β) + b _i × β
When such synthesis is performed for all the pixels 6a included in the drawing range, a transparent color shading diagram 1 is created.

Another composition method for transmissive display is screen composition. In this screen composition, for the same pixel 6a of the same terrain model (DEM), the RGB value of the elevation stage chromatic diagram 8 in the pixel 6a and the gray scale (RGB value) of the shaded map 9 in the pixel 6a are expressed by the following equations. It is a technique to synthesize.
r _t = (r _h + r _i −r _h × r _i / 255) / 255
g _t = (g _h + g _i −g _h × g _i / 255) / 255
b _t = (b _h + b _i −b _h × b _i / 255) / 255
This method is a combination of addition synthesis and multiplication synthesis, and the brightness is increased by incorporating addition synthesis. When this screen composition is performed for all the pixels 6a included in the drawing range, a transparent color shading diagram 1 is created.
In addition, overlay synthesis or the like can be adopted as another synthesis method of transmissive display other than translucent synthesis or screen synthesis.

  As described above, the transparent color shading diagram 1 is a diagram in which the shading diagram 9 having direction dependency is superimposed on the elevation stage chroma chart 8, and therefore, different drawings are created depending on the position (plane position and altitude) where the light source 10 is placed. It will be. As an example, FIG. 10A shows a transmission color shading when the light source 10 is arranged so that the light source vertical angle is 65 degrees and the light source azimuth angle is 315 degrees, and the light source vertical angle is 65 degrees and the light source azimuth angle. FIG. 10B shows a transmission color shading when the light source 10 is arranged so that the angle is 45 degrees. In FIG. 10A, the active fault 11 is clearly displayed because light is applied to the active fault 11 from a substantially vertical direction. In FIG. 10B, the active fault 11 is viewed from a direction substantially parallel to the active fault 11. It can be seen that the active fault 11 is difficult to grasp because of the light. Thus, since the transmission color shading diagram 1 has direction dependency, if the light source is arranged at an appropriate position with respect to the fine topography to be confirmed, the fine topography can be clearly grasped.

  It is also possible to superimpose another theme map on the elevation stage chromatic diagram 8 and the shaded diagram 9 superimposed by the above-described transmissive display to obtain a transmissive color shaded diagram 1. Even if the altitude stage chromatic diagram 8 and the shaded map 9 are displayed in an overlapping manner, the overall brightness is high, so that it is possible to grasp a micro-topography that depends on the directionality like a fault even when superimposed on other thematic maps. Here, as the other thematic maps, various maps such as contour maps displaying contour lines and features, and topographic maps displaying various information on the contour maps are selected. In addition, when superimposing other thematic maps, they are superimposed by the above-described transparent display.

  The transmission color shading map creation method and program, and the transmission color shading chart can grasp the existence of active faults, and can also grasp ground surface changes accompanying crustal movements over time. As a result, it is possible to grasp the movement of fault activity and the status of landslide activities, and as a result, it contributes to measures such as preventing natural disasters or reducing damage caused by natural disasters, and can be used industrially. It is an invention that can be expected to make a great contribution not only to society.

DESCRIPTION OF SYMBOLS 1 Transmission color shade figure 2 Laser measuring point 3 Horizontal axis (square lattice) 4 Vertical axis (square lattice) Vertical axis 5 (square lattice) Grid point 6 Mesh 6a (consisting of one mesh 6) Pixel 6b (four meshes) 6) Pixel 7 (mesh 6) representative point 8 Elevation stage chroma 9 Shading 10 Light source 11 Active fault A Terrain B Aircraft C Laser S Surface (when mesh 6 is placed in the coordinate system) Surface L1 (surface S is horizontal) Straight line L2 (on the surface S perpendicular to the straight line L1) δ azimuth angle (of the straight line L1) θ (vertical angle of the straight line L2)

Claims (8)

For the same terrain model, creating an elevation chart that colors with the color according to the elevation value, creating a shade map with shading the light from the light source placed at a predetermined position,
A method for creating a transparent color shading diagram, comprising: a step of superimposing the elevation stage chroma chart and the shading map so as to be transparently displayed. The method for creating a transmission color shading according to claim 1,
The terrain model is a DEM, and a pixel is created based on the DEM mesh;
Assigning an elevation value to each pixel,
Providing each of the pixels with a shade calculated based on the inclination of the pixel with respect to the incident angle of light;
Creating a color table in which RGB values corresponding to elevation values are set;
Creating a grayscale table in which the grayscale corresponding to the shade is set;
Based on the color table, a step of coloring each pixel with an RGB value corresponding to the elevation value of the pixel to create an elevation stage chart,
A method for creating a transparent color shading diagram, comprising: creating a shading diagram by displaying each pixel in a gray scale corresponding to the shading degree of the pixel based on the gray scale table. In the creation method of the transmission color shading figure of Claim 2,
A method for creating a transparent color shading diagram, wherein the step of transparently displaying an altitude step chart and a shading diagram semi-transparently combines the RGB values of the altitude step diagram and the gray scale of the shading diagram and displaying each pixel. . A function of assigning an altitude value to a pixel created based on each mesh of the DEM;
A function of calculating a shade degree based on an inclination of the pixel with respect to an incident angle of light from a light source placed at a predetermined position and imparting the shade degree to the pixel;
Based on a color table in which RGB values corresponding to the elevation values are set, a function for creating an elevation stage chart by coloring each pixel with an RGB value corresponding to the elevation value of the pixel,
Based on the grayscale table that sets the grayscale corresponding to the shading degree, a function to display each pixel with a grayscale corresponding to the shading degree of the pixel and create a shading figure,
A transmission color shading map creation program capable of causing a computer to execute a function of transparently displaying the altitude step color chart and the shading map with respect to the same terrain model constituted by a DEM. The transmission color shade drawing creation program according to claim 4,
A transmission color shading diagram creating program characterized in that the function of displaying an overlay of an altitude step diagram and a shading diagram in a translucent manner displays the RGB values of the altitude step diagram and the gray scale of the shading diagram for each pixel. Translucent color shading that overlays and displays an elevation step chart that is colored with the color according to the elevation value and a shaded figure that shades the light from the light source placed at a predetermined position for the same terrain model Figure,
The terrain model is a DEM, and a pixel created based on the mesh of the DEM includes an altitude value and a shade calculated from the inclination of the pixel with respect to the incident angle of light.
The elevation stage coloring chart is a color display of each pixel with an RGB value corresponding to the elevation value of the pixel, based on a color table in which the RGB value corresponding to the elevation value is set.
The transmission color shading diagram, wherein the shading diagram displays each pixel in a gray scale corresponding to the shading degree of the pixel based on a gray scale table in which a gray scale corresponding to the shading degree is set. The transmission color shading according to claim 6,
A transparent color shading diagram, wherein each pixel is transparently displayed by semi-transparently combining the RGB values of the elevation stage chroma chart and the gray scale of the shading chart. In the transmission color shading according to claim 6 or 7,
A transmission color shading diagram characterized by superimposing and displaying an elevation stage chromatic diagram, a shading diagram, and a contour map.