Difference between revisions of "Terrain height/slope visualization via autogenerated texture coordinates"
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== Summary of discussion on geospatial email list in 7/2015 == | == Summary of discussion on geospatial email list in 7/2015 == | ||
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| + | In data visualization it is often useful to color the y component (height) of a mesh. This is particularly evident for ElevationGrids where contouring is a proven visualization method. Therefore it would be very useful to have a new HEIGHT mode which generates texture coordinates based on the y coordinate. The most useful default would be to automatically scale to the range in height of the mesh. The parameter field could be used to define a custom range in height which corresponds to the 0 to 1 range of the S texture coordinate. T would be set to 0, eg. a 1d texture map would be expected. | ||
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| + | Here is an example of the use a height mode: | ||
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| + | http://andreasplesch.github.io/x3dom/GeoElevationGrid_texture/terrain_height.xhtml | ||
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| + | which was tentatively implemented in a forked x3dom (Mesh.js). | ||
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| + | Similary, it is often useful to visualize the spatial gradient of a surface or the slope. A new SLOPE mode for TextureCoordinateGenerator would generate texture coordinates based on the local slope angle ( implementations could derive the slope on the local normal ). By default slopes from 0 to 90 degrees would be scaled to the 0 to 1 range of the S texture coordinate. The parameter field could be used to define a custom range. T would be set to 0 and a 1d texture map would be expected. | ||
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| + | Here are two examples: | ||
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| + | http://andreasplesch.github.io/x3dom/GeoElevationGrid_texture/puddle_slope.xhtml | ||
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| + | and | ||
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| + | http://andreasplesch.github.io/x3dom/GeoElevationGrid_texture/face_slope.xhtml | ||
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| + | using a tentative implementation in a forked x3dom (Mesh.js). | ||
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| + | One could also imagine (and quite easily implement) another mode "HEIGHT-SLOPE" which uses both attributes as S and T respectively and a 2d texture map as suggested by Simon Thum on the geospatial list. | ||
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| + | These modes would be somewhat similar to the existing VERTEX and SPHERE-LOCAL modes but aimed at 1d texture maps. | ||
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| + | Finally, geospatially registered meshes would need equivalent modes using height above the geoid and slope relative to the local tangential plane to the geoid. | ||
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