I'm seeing an issue where the values being exported, a full range of 0-1 black to white, do not match the exported map, which either seems to have the gamma adjusted somehow, or values clamp or leveled up somehow, etc. This is repeatable, other relevant info and listed below...
Substance Painter version
2021.1.1 (7.1.1) build 954
exporting height based on the grayscale channel
I've tried both 16 bit and 8 bit exports with the same results
TIFF is the format and Raw is the colorspace
I don't see any adjustments to set on export in terms of gamma or color correction, so I wouldn't think that's relevant
is it possible that Painter is computing the different workflow methods I'm using while looking correct in viewport, are not being calculated correctly on export?
e.g.- I use several passthrough layers to make overall adjustments at the top of the layer stack at times, that is the case here
e.g.- I use anchor points pretty consistently because I enjoy adjusted one layer to affect many, there's some wacky stuff I'm doing at times
I'm wondering if this has anything to do with mid point... I just opened the map in Photoshop and ran a levels on it, I pulled the black up from 0 up to 128 (half of 255) and the values look correct... but again, shouldn't the viewport match the export?
What you see is the height map being normalized in the 0-255 (or 0-1) range.
The Height channel in your project is a floating point HDR channel that can display and store values below 0 and superior to 1. To keep that format, you would need to export in an HDR capable format like EXR.