Painting Roads On Uneven Terrains
Introduction
Terrains are a powerful technique for creating landscapes. The big problem arrives with the need to put color / texture maps that are properly aligned to the terrain. Sure, a 3D painting program can help, but fortunately, you don't need one.
Making the Terrain and Roads
| Start with Photoshop, Paint, Painter, or even your terrain editor (for instance in Bryce or Carrara). Paint your terrain. In this example, notice the road also has a bright area, which will be elevated in the result. |  |
| Bring the terrain into your program - in this case, Carrara. Scale to the appropriate relief height. |  |
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Move the camera to a position directly over the terrain. Make sure the terrain is largely filling the frame, and then render. This is critical, because it is this rendering that will be the basis for your painting. Since the intent is to project your texture map painting directly from above, you need to match the edges of various features as seen from this position. Ideally, center the terrain at 0/0/0 and then center the camera at the same location. Next, increase the Z position until the terrain fills the rendering. |
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Bring the rendering into your paint program, and paint on it in the appropriate colors, following the contours. You may have to go back to the renderer and shift the lights to get the best result for this stage. If you intend to use multiple texture maps (i.e. color, bump, etc.), I recommend first painting the major segments of the texture map over the rendering in shades of grey and saving that for the start point of each image. In any event, the following is the color map for this case... |
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| Finally, add the map to the shader (Carrara) or material (Bryce). For Carrara, make sure to change the shader to Projection Mapping, Flat Projection, from above. For Bryce, project the image from Object Top. |  |
| Here is a Bryce version of the same terrain... |  |
This isn't a perfect technique - there are highly complex terrains that will cause some of this technique to fail. But it is generally useful.