The blue channel should be black, so I'm very surprised by your render. It might be caused by a specific combination of setting that we haven't tried before. Could you send me a copy of your setup? I only need the Render node, Render Layer node and Camera. You can copy and paste nodes into a reply here on the forum, or attach a node clip (.tgc), or email it to
support@planetside.co.uk if you prefer.
The motion vectors are designed to work with Nuke's vector blur. Red and green channels represent motion in pixels in the X and Y directions. It should be possible to get it to work with RSMB or something like it, but that plugin's settings need to be changed or you need to offset the data. This is because Terragen's motion vectors have both positive and negative values. Zero motion is represented by the value 0 (black), not grey. Motion vectors are written directly to the file without any remapping.
Depth values:
The depth values aren't completely black except in the background. They are always stored as 1/z, measure in metres. For most scenes this means they'll be quite dark, but you should be able to extract information by gaining up the values. The range is hardcoded so that Terragen artists don't have to think about ranges when sending depth data to compositors, and the data can be consistent as the artists iterate. Camera settings don't affect the range, nor do any other settings.
This "inverted" depth map that uses 1/z allows for cleaner selection of mattes based on depth when the depth map is anti-aliased (which it is in Terragen). This can be really helpful in some situations. Using 1/depth also means that the entire scene can be stored in the file, no matter how big or small. Everything in the scene that is further than 1 metre from the camera fits in the 0..1 range, so can be stored in a 16-bit TIFF if necessary. Pixels closer than 1 metre have values above 1, but information is kept if you work with EXRs or floating point files.
But there are some cases I would prefer the depth map
not to be inverted, e.g. when using the depth map to add atmosphere in the comp.
I think Nuke has a built-in tool to convert to and from this inverted depth map. I don't really know AfterEffects so I don't know how easy it would be to convert. But I hope you can get what you want out of these maps with some colour adjustments? I want Terragen's output to be useful to people, not just limited to my own potentially narrow view of the problem, so let me know if this is still causing problems.
Matt