When you load an OBJ file into Carrara (v8.5 here in this example), you'll see a choice of options related to how the OBJ data should be used inside Carrara. Another method is to load the saved greyscale elevation map (depth map). This can be used in Carrara's terrain modeler to reconstruct the terrain. It takes far less time and memory, and viewing the result is fast too. You can then use the advanced shaders for Terrain objects that Carrara has, or change it to a shader that still uses your saved texture as well.

See both methods here. Scroll down to see the video for method #2

Method #1 - Loading the OBJ file that was saved

Here's a sample screenshot:

You'll notice that Carrara can created the objects as Facet Meshes or as Vertex Primitives. The latter is the default. This is useful if you plan on doing vertex-level editing on the imported surface. However, it will likely take more memory and more time to load, because the internal data structure is quite different when you want to identify and edit each vertex and facet and line through the Vertex modeler, vs. just holding a mesh that is ready to be rendered but doesn't need editing comparable controls.

For large terrain meshes, it may therefore make sense to use the Facet Meshes mode.

Note that either way, it can take quite a while to load such mesh terrain models. If you have a fairly high resolution image as the unerlying elevation map, the mesh file in OBJ format can easily be dozens or hundreds of megabytes in size.

Below is a comparison with an example of a mesh of 1800x1012 elements in the original greyscale height map from which the terrain mesh was created in Howler's 3D Designer. (Note that this uses a modified version of the exporter, which allows for the u,v addresses to be exported with the mesh. You can grab this free update patch for improved OBJ export here. )

The resulting saved OBJ file in this example is very big:

 - 278 MB as uncompressed clear text
 - 41.2 MB compressed as zip
 - 14.6 MB compressed with 7-zip (.7z file).

You'll definitely want to use 7-zip for archiving :-)


Here's the original greyscale elevation map, with erosion and sediments from 3D Designer:





Here's a texture map for it




Here are renderings in PD Howler's 3D Designer:





Here we have imported the saved OBJ into Carrara as a mesh, then added the texture in the shader.


 
 
Here's a rendering in Carrara, save terrain,  with different camera position added sky





Here we have used the same terrain as a surface replicator for a fir tree

Method #2 - Reconstructing the Terrain mesh from the saved Elevation Map

back up to method #1 with importing the OBJ file