The displacement outputs on Gaea have been patchy at best, for quite a while what was supposedly 32bit .exr were actually 16bit.
Agree with WAS that .exr (or any 32bit output) should output values that actually represent the true height of the terrain, i.e if your terrain is 600 meters high, then the largest value in the displacement image should be 600 also. This is how Terragen does it and it is very accurate and a good fail-safe way of approaching it. I think World Machine can now output .exr in the same way.
There is a way to accurately load your Gaea displacement map in Terragen:
- Export the displacement map from Gaea as 32bit .tif. Set Output Range to Natural Elevation.
- Make a note of the Terrain Definition in Gaea - you need to note Height and Scale, the default values are 2600 and 5000 respectively.
- Load the .tif into Terragen via a Heightfield Load node.
- Connect the Heightfield Load into a Heightfield resize node. Check only Re-size in meters and set both values to 5000 (the Gaea scale value).
- Add and connect a Heightfield adjust vertical, click Multiply Height by and set to 2600 (the Gaea height value).
This only works when output is 32bit tiff, and you can't use this workflow if you've rendered out a 32bit exr, I really don't know why - if you render out displacement maps from Mudbox in either 32bit .tif or .exr, they contain the same values.
p.s I did ask Quadspinner if they planned to output exrs in the same manner as Terragen and they replied:
"Currently, this is not directly possible at the moment. But it is in our backlog and will be implemented in the near future."
But that was about 9 months ago