In the right side window under Dimensions, you can set your height map aspect ratio and resolution. Now you can move the monkey around with the right mouse button. To get to a more useful view, click on View for the lower right window and select the Top camera.

At first, it seems that the results are backwards from what we want, with the higher parts darker, but if you rotate the lower right scene with the middle mouse button, it becomes clear that the monkey face is actually facing down, so that’s fine.

That shows you what the result will look like. It shows a strange monkey face in the lower right window.

So I am writing down what you need to do in order to make use of this file. It doesn’t have a learning curve so much as a learning wall. Whenever I encounter Blender, a little shiver crawls up my spine.

I thought it might be useful to maybe one or two other people here. After much searching, complicated by the fact that most people want to go in the opposite direction, I came across this Blender file. What I had was a bas relief STL from Thingiverse, what I needed was a grayscale heightmap. I wanted to try the new 3D Engrave setting, and wanted to use a true heightmap, not a photo.

Blender stl