There may be times when you need detail in some areas but don't want to wait while detail renders everywhere at a high Fractal Depth. A typical example is a road. Here's how to use a Maximum Fractal Depth Texture to save render time. Screen captures are from VNS 2 but the method is the same in WCS 6.
1. Download FD.zip to your WCSProjects folder and extract to WCSProjects\FD. It contains the finished project and the image you'll need for the Maximum Fractal Depth texture.
2. Begin a new project and create a simple 1 km x 1 km terrain with the Terrain Generator.
3. Change the Rows per Tile and Columns per Tile to 101. No need to spend more time rendering our test project than necessary.
4. I created a simple mask in Photoshop (FD Texture.iff). It's in the project zip download. It's square to match the terrain.
5. Add the image to the Image Object Library.
6. Add a Geo Reference, select the DEM in the Database Editor, and Snap to selected DEMs.
7. Add a Color Map with the image we just added. It'll give us a reference for later on. Disable the Color Map after running a preview render.
8. Open the Terrain Parameter Editor and select Constant. Add a Maximum Fractal Depth Texture.
9. Choose Planar Image as the Selected Element. Select the FD Texture.iff image from the Image Object dropdown list.
10. Increase the Maximum Fractal Depth to 7.
11. It's hard to see the effect in the plan render.
12. Enable the Color Map and render a preview. Digitize a Terraffector road on the render in the white swatch. Disable the Color Map and render a preview. My render time was 10 minutes with the Max FD texture.
13. Let's see how much time we saved by using the Max FD texture. Disable the texture.
15. This render took 52 minutes with a Maximum Fractal Depth of 7 everywhere.
16. If you're curious, reduce the Max FD to 0 and try a render. Fast but lousy road detail.