It would be nice to be able to render albedo and normal maps for denoising. The rendered images always come out with at least a little bit of noise, and I would like to fix that.
Another option would be to integrate a denoiser into Terragen itself. Is that even possible? I know Blender did it.
Sorry for the late reply here. Are these landscape renders or sky-only renders? We don't output this data for clouds yet, but albedo and normal can be output for surfaces. These are the "Surface Diffuse Colour (before lighting)" and "Surface Normal" render elements.
https://planetside.co.uk/wiki/index.php?title=Render_Layers_and_Render_Elements
Depending on what your denoiser expects you might need to shift the values in the normal element to put them in the expected range.
As a side note, some denoisers work a lot better on Terragen images if you render with the pixel reconstruction filter set to "Box" (on the Filter tab of the render settings), and it might help to disable "Anti-aliasing bloom" as well.