TW201905853A - 3D terrain map and manufacturing method thereof performing terrain slope and terrain openness calculation on the numerical terrain model, and coloring the terrain slope and openness - Google Patents

Abstract

The invention provides a three-dimensional terrain map and a manufacturing method thereof. The map of the invention can solve the problems that the red map cannot clearly determine the elevation fluctuation and that the terrain elevation distribution cannot be known. The method of the invention comprises performing terrain slope calculation and terrain openness calculation on the numerical terrain model and coloring the terrain slope and openness by stereoscopic color gradation to obtain a three-dimensional terrain map.

Description

 3D terrain map and manufacturing method thereof  

The invention relates to a topographic map and a manufacturing method thereof, in particular to a three-dimensional topographic map with chroma gradation toning and a manufacturing method thereof.

In recent years, Light Detection And Ranging (LiDAR) technology has been able to produce high-precision Digital Surface Model (DSM) and Digital Elevation Model (DEM), which can even be accurate. If you can put this technology into domestic soil and water conservation, soil and sand disaster prevention, land planning, disaster prevention management, environmental monitoring and resource exploration, it will be of great help. However, if traditional methods such as contour lines, shadows, or layered coloring are used to express DSM and DEM, important information will be missed because the map cannot fully display the topography. Take the DSM of Miaoli Huoyanshan in Taiwan as an example (see Figure 1a, 1b) (regional plane range: TWD97 coordinates EW direction 221659~222682m; NS direction: 2694761~2695798m, regional elevation: 158~533m), this area is famous evil place Terrain, due to low soil water permeability, rainwater can not penetrate, plants are not easy to grow, and the surface erosion is strong, causing a lot of gully erosion. The layered color map (Fig. 1b) can only easily determine elevation changes and cannot directly observe the terrain type. Although the shadow map (Fig. 2a, 2b) can show the characteristics of the eroded topography, it contains many shortcomings, such as the shadow itself will cover the finer terrain, and the opposite direction of the incident light source will cause the terrain to be misjudged, resulting in It is impossible to fully present the real terrain.

Some companies have proposed a technical scheme for red maps, such as TWI285852, JP4272146, JP3670274, JP5281518, CN17115688, CN102214410A, USP7876319, USP7764282, etc. These cases have red maps stacked on a layered color map to form Red maps with elevation values, although these cases can solve the above problems, but the judgment of elevation fluctuations is not very clear, and it is impossible to grasp the elevation distribution of the terrain, so the effect is not satisfactory.

In order to solve the above prior art problems, the present invention provides a 3-dimensional terrain map and a method of fabricating the same.

The three-dimensional topographic map of the present invention and the manufacturing method thereof comprise the following steps: preparing a numerical terrain model; performing terrain slope calculation on the numerical terrain model; performing terrain openness calculation on the numerical terrain model; and stereoscopic color gradation on the terrain Slope and openness to color.

The above-mentioned 3D terrain map and the method for manufacturing the same, the method calculates the terrain openness, the terrain slope and the elevation value by Fortran syntax, integrates the calculation and draws the map with the drawing software GMT.

The above-mentioned three-dimensional topographic map and its manufacturing method, wherein the terrain slope is calculated by using a four-neighbor method, a weighted eight-neighbor method or an equal-eight-neighbor method.

The above-mentioned 3D terrain map and the manufacturing method thereof, wherein the terrain openness in the method is an average value of the longitudinal angle formed by calculating the horizontal distance and the elevation difference between the grid point to be calculated and the surrounding grid point, the method defines the ridge Part of the terrain has a negative openness and the valley has a positive openness.

The above-mentioned three-dimensional topographic map and the manufacturing method thereof, wherein the method is to perform color grading by a flat color palette, which is composed of the terrain slope and the terrain openness, wherein the flat color palette has an X-axis and Y-axis, the X-axis of the flat palette is a terrain openness, the color is configured to be a first color gradient to a second color; the Y-axis of the flat palette is a terrain slope, and the color configuration is gradient from the first color To a third color, and in one embodiment the method converts the 2D plane to a 3D aerial view.

The above-mentioned three-dimensional topographic map and the manufacturing method thereof, wherein the method is to perform color grading by a stereoscopic color palette, which is composed of the terrain slope, the terrain openness and the terrain elevation, wherein the stereoscopic tone The color wheel comprises an X-axis, a Y-axis and a Z-axis. The X-axis of the stereo color palette is a terrain openness, and the color is configured to be a first color gradient to a second color; the Y-axis of the stereo color palette is a terrain The slope, the color configuration is gradiented from the first color to the third color, the Z-axis of the stereoscopic palette is an elevation value, and the color configuration is gradiented from a fourth color to a fifth color.

The above-mentioned 3D terrain map and the manufacturing method thereof, wherein the terrain has a range of -90° to 90°, and the terrain slope ranges from 0° to 90°.

The 3-dimensional topographic map of the present invention includes toning with stereoscopic color gradation in the slope, openness and elevation of the numerical terrain model.

The method and the map made by the invention are a new technology for expressing the topography of the terrain in the form of terrain rendering, and the surface elevation, the terrain openness and the terrain slope are used, and the appropriate stereoscopic color gradation is used to express the terrain fluctuation. In the past contour map, shadow map, layered color map or even red map, the 3D terrain map of the present invention can provide visually superior stereoscopic effect, and can be easily discerned by the observer with the naked eye. In addition to its rich and detailed surface information, observers can easily observe changes in surface elevation at the same time, which can solve the problem that the red map cannot clearly determine the elevation fluctuations, and thus cannot grasp the elevation distribution of the terrain. Compared with the prior art, with the present invention, it is possible to provide an analysis and estimation of the potential of the soil and sand disaster on the hillside, and provide relevant design planning and risks related to the unit's disaster prevention, soil and water conservation, environmental monitoring and resource exploration, and soil sand disaster potential. Evaluation.

100‧‧‧3 dimensional terrain map production method

10, 20, 30, 40 ‧ ‧ 3D terrain map production method 100 steps

Figure 1a shows the aerial view of Miaoli Huoyan Mountain.

Figure 1b is a layered color map of Figure 1a.

The shadow map of Miaoli Huoyan Mountain in Figure 1a of Figure 2a and 2b.

FIG. 3 is a flow chart showing the steps of the method for manufacturing a 3-dimensional terrain map of the present invention.

Figure 4 is a schematic view of the terrain slope in the present invention. Where A is the grid point to be calculated and θ is the slope value.

Figure 5a is one of the slope calculation methods of the present invention. The four-neighbor method is shown.

Figure 5b is one of the slope calculation methods of the present invention. The weighted eight-neighbor method is shown.

Figure 5c is one of the slope calculation methods of the present invention. The equal-eight-neighbor method is shown.

Fig. 6 is a schematic view showing the topographical opening of the light source receiving amount in the present invention.

Figure 7a is a schematic view of the open topography of the present invention.

Figure 7b is a schematic view of the negative terrain opening degree in the present invention.

Figures 8a and 8b are schematic views of the terrain in the present invention. The elevation and slope values of point A and point A' are the same, but the terrain has different degrees of openness. 8a is the topography with better openness, and 8b is the terrain with poor openness.

Fig. 9 is a schematic view showing the radius of the cover window in the terrain opening degree in the present invention. The small circle inside the circle is to calculate all the grid points in the radius.

Figure 10 is a schematic view showing the radius of the window of the present invention. Where T ₁ is a shorter search radius and T ₂ is a longer search radius.

Figure 11 is a comparison of topographical openness maps of different cover window radii in the present invention.

Figure 12 is a comparison of the topographical openness maps of different terrain contrast values in the present invention.

Figure 13a is a three-dimensional color map of the three-dimensional topographic map of the present invention.

Figure 13b is a flat color palette of a three-dimensional topographic map in the present invention.

Figure 14 is a 3D terrain map palette (left) of various color combinations in the present invention, and a corresponding 3D terrain map (right).

Figure 15 is a comparison of the base maps of different openness ranges and different slope ranges in the present invention.

Figures 16a, 16b, and 16c are three-dimensional views of the Miaoli Huoyan Mountain of the present invention.

Figures 17a and 17b are three-dimensional topographic maps of the Miaoli Huoyan Mountain of the present invention.

In order to enable the reviewing committee to have a better understanding and recognition of the features and features of the present invention, the following preferred embodiments are illustrated with the following description:

Please refer to FIG. 3 , which is a flowchart of a method 100 for fabricating a three-dimensional topographic map according to the present invention, which is a method for forming a 3D terrain map having a three-dimensional chroma gradation by a numerical model in a color scheme. 100 is described and illustrated as a series of acts or events as follows, however, the order of the actions or events is not limited thereto, for example, some of the actions may be deviated from the descriptions and/or the order of descriptions mentioned herein, but different The sequence is performed and/or concurrent with other actions or events. In addition, not all of the actions described herein are necessarily implemented in one or more embodiments or concepts, and one or more of the actions described herein may be performed in one or more separate acts and/or stages. .

The method 100 for manufacturing a three-dimensional topographic map of the present invention comprises the following steps: preparing a numerical terrain model 10, performing a terrain slope calculation on a numerical terrain model 20, performing a terrain openness calculation on a numerical terrain model, and performing a terrain color gradation on the terrain. Coloring 40 for slope and openness. The 3-dimensional topographic map produced by the method has a color gradation with a stereo chroma scale in the slope, the openness and the elevation of the numerical terrain model.

In step 10, a numerical terrain model is provided, which is a three-dimensional numerical terrain model, which can be obtained by using Light Detection and Ranging (LiDAR) or aerial photography.

In the method of an embodiment, the terrain spread, the terrain slope, and the elevation value are calculated by using the Fortran program syntax, and the map is integrated and calculated by a drawing software such as GMT. The following is a description:

In step 20, the slope calculation is performed on the numerical terrain model. In the embodiment, the terrain slope is a degree indicating the inclination of the terrain. In terms of slope calculation, the terrain slope value calculated by the present invention is in the range of 0° to 90°. Value, no negative slope value, programming three terrain slope calculation methods, namely four neighborhood method, weighted eight neighborhood method and equal weight eight neighborhood method. All three algorithms use a 3x3 moving window, the formulas are as follows:

1. Four neighborhood method :

c ₀ is the grid point to be calculated, S is the terrain slope value, e ₁ ~e ₄ is the surrounding grid value, and d is the grid unit size. The four-neighbor method calculates only the slope value between the grid point to be calculated and the adjacent four grids.

2. Weighted eight-neighbor method :

c ₀ is the grid point to be calculated, S is the terrain slope value, e ₁ ~e ₈ is the surrounding grid value, and d is the grid unit size. The weighted eight-neighbor method calculates the slope value between the eight grids around the grid point to be calculated, and the nearest four grids need to be weighted.

3. Equal power eight neighborhood method :

c ₀ is the grid point to be calculated, S is the terrain slope value, e ₁ ~e ₈ is the surrounding grid value, and d is the grid unit size. The equal-eight-neighbor method calculates the slope value between the eight grids around the grid point to be calculated, and all the surrounding grids are equally weighted.

The three-dimensional terrain map program of the present invention can freely select any terrain slope calculation method, and the differences of the three algorithms can be compared in FIG. 5a, 5b, and 5c, although the difference is not large, but the weight can be roughly judged from the naked eye. The neighborhood method and the equal-eight-neighbor method present more delicate results.

In step 30, the topographical openness calculation is performed on the numerical terrain model. In the embodiment, the terrain openness is a simulated light source receiving amount to create a stereoscopic effect, as shown in FIG. 6, the light source receiving amount is more than the topographic type color shift. White, on the other hand, the valley is dark, so it can replace the shadow map and create a perfect three-dimensional effect. The terrain openness defined by the present invention is an average value of the longitudinal angle formed by calculating the horizontal distance and the elevation difference between the grid point to be calculated and the surrounding grid point. Taking Figs. 7a and 7b as an example, the grid point A to be calculated is located in the valley, and the longitudinal angle formed by the point A and a certain grid point B at the upper periphery is (elevation angle), but if point A is at the top of the mountain, the vertical angle formed by point A and point B is - (depression angle), so the terrain openness of the present invention is defined as a negative value of the ridge portion (good terrain openness), and a positive value for the valley portion (difference in terrain openness), so the value ranges from -90° to 90°. between. The 3D terrain map of the invention has excellent terrain rendering effect, and the most important factor is the terrain openness value, the advantages of which are shown in the topographical diagrams of Figures 8a and 8b, and the elevation and slope values of points A and A' are the same. Then, the points A and A' will have no difference in contour, layered color or shadow map, but for the 3D terrain map of the present invention, the hills are different in point A and A' terrain. The upper will present a distinctly different color. The formula for terrain openness is as follows:

Before calculating the terrain openness, it is necessary to determine the value of the radius (T) of the cover window (in km). The selection of the radius of the cover window is also one of the features of the invention. The openness calculation program of the present invention allows the user to freely Set the radius value (T) of the window in the openness calculation formula. Figure 9 is a schematic diagram. The calculation is performed with the calculated grid point A as the center, and all the grid points (circle inside the circle) and points within the radius T of the cover window. The sum of the longitudinal angle values formed by A, and then take the average value as the topographical openness value of the study (range between -90° and 90°). The radius of the cover window (T) is a very important parameter of the invention, which directly affects the result of drawing the 3D terrain map of the present invention. Selecting the radius of different cover windows will have a great influence on the terrain drawing. If the radius of the cover window is too small, it cannot be complete. Searching for adjacent terrain grid points around the calculation point will result in errors in the calculated terrain openness. As shown in Figure 10, when calculating the terrain openness, T ₁ is the shorter cover window radius, and T ₂ is the longer cover window radius. If the terrain openness is calculated by the T ₁ radius, the cover window radius is too short to search for the point. The terrain of B is misunderstood that the openness of the ground is good and it is white in the 3D terrain map of the present invention. If the radius of the T ₂ is used for calculation, the radius of the cover window is long, and the point B terrain is also searching for the grid point. The calculated result will be darker in the 3D terrain map of the present invention (closer to the correct terrain). Figure 11 is a topographical openness map calculated using different mask window radii T when the fixed terrain contrast value is 1 (the terrain contrast value definition will be described later). It can be found from Fig. 11 that if the mask window radius is set too large, the terrain is presented. It will be too flat, and many subtle terrain features will disappear, and it is impossible to effectively distinguish the terrain fluctuations. If the radius of the window is set too small, the terrain noise is too much, which is not conducive to the interpretation of micro-topography. The radius of the window has no fixed optimal length, and the optimal window width of the DEM of different grid sizes is different, depending on the fineness of the terrain to be presented.

In addition to the radius of the cover window, the present invention also increases the terrain contrast value (S) coefficient (no unit) in the calculation of the terrain openness. If S=2, it means that the elevation difference of the DEM grid point is multiplied by 2 Times, other values are also analogous, which will make the terrain fluctuations more apparent in the 3D terrain map presentation of the present invention. Figure 12 shows the results of the terrain openness map when the fixed cover window radius T=0.03km, if various terrain contrast values are used, it can be found from Fig. 12 that if the terrain contrast value is increased, the terrain openness map will be black and white. More obvious, the three-dimensional sense will be better, but if the value is too large, the terrain will be too deep to be interpreted. Overall, the optimal window window radius (T) and terrain contrast (S) will be chosen based on grid size, subjective vision, and terrain status.

Compared with the red map of the prior art, the red map uses the tail root valley to calculate the terrain openness value, so the present invention is different. In the program setting, the method of the present invention provides the window window radius value (T) and the terrain contrast. The value (S) is for the user to select, and the user can select the optimum cover window radius value and terrain contrast value according to his own needs to draw the best 3D terrain map.

In step 40, the terrain slope and the opening degree are toned in a stereo chroma scale. In the embodiment, the flat palette and the stereo palette are provided to perform color adjustment.

The 3D terrain map palette used in the present invention is shown in Figures 13a, 13b, and the user can select a stereo palette (Fig. 13a) or a flat palette (Fig. 13b) to draw a 3D terrain map. The following will further explain the two color palettes:

The flat palette (Fig. 13b) consists of terrain slope and terrain openness, with X-axis and Y-axis. The X-axis of the flat palette is the terrain openness (unit: degree), ranging from -90° to 90°. (The range is customizable), the color is configured as the first color, such as the white (grayscale value 255) gradient of the embodiment to the second color, as in the embodiment, black (grayscale value 0), which means that the terrain is more open. The grid point should have more illumination, so the color is white, and the grid point with worse terrain is worse. Because the light receiving amount is small, the color simulation is black; on the other hand, the Y axis is the terrain slope ( Unit: degree), the range is 0° to 90°, and the color configuration is from the first color, such as the white gradient to the third color of the embodiment, as in the embodiment, red (RGB color: 255, 0, 0, R: Red, G: green, B: blue), which represents the steeper slope of the terrain, the more reddish the color, and the flatter terrain is whiter. The invention provides a plurality of color selections for the user in the color palette design. Therefore, in addition to the above color combination, the user can easily select different color combinations according to his own preference, as shown in FIG. 14 for red, green, and Blue and other colors. In addition to the combination of terrain openness -90° to 90° and terrain slope 0° to 90°, the present invention allows the user to easily change the combination of terrain openness and terrain slope to draw a 3D terrain map, Figure 15 The three-dimensional topographic map composed of different open range and slope range of the invention, wherein the invention selects three openness ranges and slope ranges for comparison, and it can be clearly seen from Fig. 15 that if the openness range value is reduced, black and white The level will be more clear, the three-dimensional feeling is better, but the terrain like the valley will be too dark to be discerned. If the slope is narrowed, the map color will be redder. If it is too red, it will lead to a false positive judgment. The choice of color should be adapted to local conditions.

Although the flat palette can not present elevation information, when drawing, the 3D terrain map can be directly converted from 2D plane to 3D aerial view (as shown in Figures 16a, 16b, 16c), showing the real fluctuation of the surface according to different perspectives, so that Aspects of the terrain.

The stereo color palette (Fig. 13a) adds a Z-axis elevation value to the flat palette, and the range is appropriately set according to the actual elevation of the terrain, and the color is configured to be a fourth color gradient to a fifth color. The color configuration can also be easily selected by the user. For example, in Fig. 13a, the elevation value is gradually increased from low to high to a green value of 255 (RGB color matching: 0, 255, 0). If the ground level is higher, the green color is increased. To judge the elevation. Figures 17a and 17b show the 3D topographic map results (1m DSM) of Miaoli Huoyanshan, and Fig. 17a shows the results drawn by the stereoscopic palette of Fig. 13a. All colors of the stereo palette can be freely selected, for example, the elevation change can be changed from blue to green (low to high), as shown in Figure 17b. Whether it is 17a or Fig. 17b, in addition to observing the micro-topography of the evil eclipse, the observer can easily observe the slope and the elevation of the terrain, and can solve the problem that the red map cannot grasp the elevation distribution of the terrain.

The invention utilizes Fortran syntax to compose a 3D terrain map program, and draws a map by using the free drawing software GMT. This figure has great advantages for interpreting the terrain, and can prove its micro-topography in the 3D terrain map with a small grid. The presentation is very obvious. This map can make the terrain clear and help the map user to visually observe the topography of the terrain for terrain interpretation and observe the elevation changes of the terrain. Compared with the prior art, the three-dimensional topographic map of the present invention can express the fine terrain of the DEM, which is more useful for the map user to read the ridgeline, the valley line, the geological fault zone and the forward slope from the map. Areas such as rock formation collapse and earth-rock flow potential areas are suitable for research topics related to landslides, ground slips, earth-rock flows, etc., or for changes in erosion grooves, topographic changes, and increase or decrease of artificial structures. The observer obtains information from the 3-dimensional topographic map of the present invention. Overall, the three-dimensional topographic map of the present invention and its manufacturing method should provide good reference and practical value for disaster prevention, soil and water conservation, and environmental monitoring.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. All of the related art in accordance with the present invention are equivalent to the present invention. The scope of coverage.

Claims (13)

 A method for manufacturing a three-dimensional topographic map includes the following steps: preparing a numerical terrain model; performing terrain slope calculation on a numerical terrain model; performing terrain openness calculation on a numerical terrain model; and terrain slope and opening degree in a stereo chroma scale To do the coloring.    For example, the method for manufacturing a three-dimensional topographic map described in claim 1 is to calculate the terrain openness, the terrain slope, and the elevation value by using the Fortran grammar, and integrate the calculation and draw the map with the drawing software GMT.   For example, the method for manufacturing a three-dimensional topographic map described in claim 1 or 2, wherein the terrain slope is calculated using a four-neighbor method, using a 3x3 moving window, the formula is as follows: c ₀ is the grid point to be calculated, S is the terrain slope value, e ₁ ~e ₄ is the surrounding grid value, and d is the grid unit size. For example, the method for manufacturing a three-dimensional topographic map described in claim 1 or 2, wherein the terrain slope is calculated using a weighted eight-neighbor method, using a 3x3 moving window, the formula is as follows: c ₀ is the grid point to be calculated, S is the terrain slope value, e ₁ ~e ₈ is the surrounding grid value, and d is the grid unit size. For example, the method for manufacturing a three-dimensional topographic map described in claim 1 or 2, wherein the terrain slope is calculated using an equal-eight-neighbor method, using a 3x3 moving window, the formula is as follows: c ₀ is the grid point to be calculated, S is the terrain slope value, e ₁ ~e ₈ is the surrounding grid value, and d is the grid unit size.  For example, the method for manufacturing a three-dimensional topographic map described in claim 1 or 2, wherein the terrain slope value ranges from 0° to 90°, and has no negative slope value.   For example, the method for manufacturing a three-dimensional topographic map described in claim 1 or 2, wherein the terrain openness in the method is to calculate a horizontal distance and an elevation difference between the grid point to be calculated and the surrounding grid point. The average value of the longitudinal angle formed is as follows: Where S is the topographic contrast value  For example, the method for manufacturing a three-dimensional topographic map described in claim 7 wherein the method defines that the terrain of the ridge portion has a negative openness, and the terrain of the valley portion has a positive openness value, and the value ranges from -90. ° to 90 °.    The method for manufacturing a three-dimensional topographic map according to the first or second aspect of the patent application, wherein the method is to perform color grading by a flat color palette, the flat color palette consisting of the terrain slope and the terrain openness. Wherein the flat palette has an X-axis and a Y-axis, the X-axis of the flat palette is a topographical width, and the color is configured to be a first color gradient to a second color; the Y-axis of the flat palette is The slope of the terrain, the color configuration is gradual from the first color to the third color.    The method for manufacturing a three-dimensional topographic map according to claim 9, wherein the method converts the 2D plane into a 3D aerial view.    The method for fabricating a three-dimensional topographic map according to the first or second aspect of the patent application, wherein the method is to perform color grading by a stereoscopic color palette, the topographic color palette is sloped by the terrain, and the terrain is open. And the terrain elevation, wherein the stereo color palette comprises an X-axis, a Y-axis and a Z-axis, wherein the X-axis of the stereo palette is a terrain openness, and the color is configured to be a first color gradient to a second color. The Y-axis of the stereoscopic palette is a terrain slope, the color configuration is gradually gradient from the first color to the third color, the Z-axis of the stereo palette is an elevation value, and the color configuration is from the fourth color to the fifth color. .    The method for manufacturing a three-dimensional topographic map according to claim 9 or claim 11, wherein the terrain has a range of -90° to 90°, and the terrain slope ranges from 0° to 90°.    A 3D terrain map containing tones with stereoscopic color gradations in the slope, openness, and elevation of a numerical terrain model.