I had a chance to look at it in more detail and I think it seems like either a bug in the Displacement to scalar shader or default behavior - if Matt is reading this, he could confirm
The displacement to scalar shader only seems to work as you'd expect if you put it before the compute terrain node. I don't know why that should be, and it does limit options of where to sample the node tree.
But the workaround is to connect a Y to scalar after a Displacement to vector to get a heightfield rather than a VDM - see the attached TGD.
QuoteOn another note, I still don't understand how a VDM works.
Think of it as 3 scalar maps or heightfields combined in one file- the green channel is the standard Y displacement equivalent to a heightfield, so yes you can just isolate that channel in a VDM to get a regular heightfield. The red and blue channels then push the displacement in X and Z coords.
QuoteHow can the map do the offset for more than one surface
Not sure what you mean, but VDM can handle quite extreme overhangs like this:
Good point though, check out the attached TGD, which is exporting from a simple scene created from a heightfield - render the Vector_DIsplacement render node and look at the red and blue channels - there's no information in there, as the scene is derived from a heightfield itself which is only displacing upward in Y.
It would be different if you add something like fake stones (which are vector displacements in themselves) then the VDM would have those extra channels populated.
So as you are basically upscaling and merging DEM files in your Terragen scene, you can just export a standard scalar heightfield and save some disk space.
QuoteI am exporting different terrains when I run multiple instances of Terragen.
I think a height field render will work reliably now - you could bypass your multiple instances of Terragen and set up a queue of renders. You can grab a copy of Deadline (
https://www.awsthinkbox.com/deadline) which is free if you have three machines or less, and set up a queue to render overnight - it has a prebuilt set up for Terragen and for this use is quite easy to setup.
QuoteI am exporting different terrains when I run multiple instances of Terragen.
I'm currently writing a script for Terragen to Maya that includes a renamer for a linear image sequence to the Mudbox file naming convention, looks like the World Machine naming is similar and should be easy to write a renamer for that too. I'll probably make a standalone version of the renamer to work outside Maya.
terragen_export_displacement_v01_01.tgd
