I'd like to generate a height map from my scene that goes from -50m to +50m (the idea is to use that height map to flatten out ocean waves as they get nearer to the shore, and possibly more advanced effects later).
My problem is that my height map values are not in the expected range. I get near-black, but no white, even in parts where there is nothing in front of the camera (actually, this only happens in the center of the depth image, where the near clipping plane "cuts off" the top of the terrain; that terrain actually has a square base that is somewhat higher up than -50m - see the attached screenshot - so I do not expect white pixels anywhere except in the clipped-off area).
The camera is orthographic, looking straight down from a height of 51m, with the near clipping plane at 1m and the far clipping plane at 101m. I was expecting this to cover the range from +50m to -50m I mentioned above.
In the compositor, I use the Depth output of the Render Layers node, which I plug into a Map range that maps the range 1..101 to 0..1. And that's my output.
But like I said, there is no white on it. The brightest pixel that I get is a CECECE.
Can someone tell me what I'm doing wrong?