Rhino Terrain Surface from image using Heightfield and Bump Texture Tools and GIMP, CGSD
The Rhino feature that I have been working with the most is the Heightfield map generator command.
It took me a while to figure out that this command is not best used with just a bitmap image taken with a digital camera. I learned that making a real heightmap (I used the shape-from-shading filter in GIMP) and saving it as a bitmap is the way to go.
When the real heightmap of the image is imported into Rhino 3.0 and the Heightfield from image command is used on that, the result is a detailed and accurate NURBs surface of the terrain.
Just a bit of Gaussian blur of the image before using it in Rhino 3.0 helps smooth out the few rough edges.
I recently uncovered a better heightmap maker than GIMP. It is a Photoshop plug-in from CGSD that is part of their Bump Texture Tools package. It is called Shape from Shading.
The CGSD package also includes a stereo image inverter.
The GIMP program makes heightmaps OK but GIMP's shape from shadow filter was written for a satellite, and that won't help most of you.
The CGSD plug-in for Photoshop is much more general in its application. See this site: www.cgsd.com/bumptexture
Another good preprocessing program is the shadow reduction filter plug-in for Photoshop, SR Pro.
This works well on the original image before converting it to a heightmap with the CGSD filter shape from shading.
When you use these two preprocessing filters, the level of detail in terrain maps generated with your Heightfield command is infinitely better than just using a regular digital camera photo image without any preprocessing.