So I firstly tried an old fashioned method
1.Get a moon pole and a star map from NASA
Assign a material with moon's base color/displacement texture to a little sphere.
Assign a material with Celestial Star map texture to a big sphere, or the celestial sphere (the backdrop)
2.Add a distant light as sunlight
Then, the problem happens
Problem1.Celestial sphere blocks the distant light, and the moon appears black.
Problem2. The star map is much too bright. The empty area with out stars should have ZERO brightness, however, the default translation of the NASA star map makes the map "glowy"
So for problem 1 I tried
1.Light mask
2.Light bank
but none of these work. It seems that, these function deal with if the object is lit rather than it the object will block the light rays.
For problem 2, I know that in unreal there is a shading model called unlit so you can just use a fake star map as a color emmision map to do the star back drop. But I haven't found how to do that in houdini yet. I tried to do that with environment light, that only makes things worse, the empty areas are even brighter.
So I would like to know that is there anything to bypass this?
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PS: I know that in real world you have exposure problem of optical device, so if you can see very close(astronomically) sun-lit objects,you can not see stars. But for artistic porpuse, how can we do this? I know houdini can do composition, so we can render to .exrs separetly and compose. But for best artistic result, which work flow should I try. Now lets try to add some challenge, add some volume nebula effect. Then I think at least the volume, sunlight and the moon should be in the same scene.