Shadows not showing up correctly
I'm working on the lighting on an office scene And I'm seeing some issues in the shadows from some of the lights. I've gone through what I think it could be with no luck and was hoping someone else may have an idea or be able to point me in the right direction.
In the following picture there are two lamps, both blueprint lights and both completely identical, but only the one on the left is showing a shadow on the wall behind it correctly. The light is inside the bowl of the lamp so it makes sense that there would be a sharp shadow on the wall where the light gets cut off by the lamp. With the lamp on the right there is no shadow showing up on the wall behind it, however the shadow from that lamp is showing up correctly on the bookcase and computer monitor next to it.
This doesn't seem to be a lightmap issue, I've checked the lightmap on the wall mesh and all the UVs have their own, even sized space. I've rendered this image with a large resolution on the LM as well to see if that would help. They are stationary lights but there are only 3 of them in the scene and none have an X through them, so overlapping can't be the issue, and I have a Lightmass Importance Volume around the whole scene.
The wall is also one solid mesh, so I can't figure out why it would render an identical light 2 different ways. If anyone has any suggestions It would be greatly appreciated, I'd really like to understand as much about lighting as I can in here.
asked May 22 '14 at 01:00 AM in Rendering
Hi Joe1029 -
I have found out what is causing the problem, but no immediate solution as of yet. If you move your desk lamps to opposing corners of the desk the shadows will render correctly, this leads me to believe that there is an issue with the overlapping stationary light in the scene.
I will let you know if and when we find root cause or solution
answered May 29 '14 at 03:24 PM
Lovecraft_K ♦♦ STAFF
Try changing the lights to movable as a test - if the shadows now show up correctly then you know it is a lightmap issue, usually with the lightmap UVs on the receiving mesh. I know you mentioned you checked that your UVs are unique but that's all I can think of that it could be.
answered May 22 '14 at 01:35 AM
Hi Joe1029 -
I came about that suggestion knowing how light works in a real world setting and if you have enough indirect light it will fill in shadows created by a direct lighting source. What I was seeing in your pictures was the tight corner with a lot of indirect lighting coming from the desk and bookcase. So this seems this is the culprit to getting your direct shadow back.
You are saying that you tried different materials, but have you played around with roughness, specular and metallic settings in the bookcase and desk material to limit the objects reflective quality to a very diffuse settings (Roughness close to 1, Metallic at 0).
Ultimately though you will probably want to adjust the Desk Lamp PointLight's Indirect Lighting Intensity down to get less bounce contribution in the level. A setting of zero should render only the direct lighting itself and create the hard shadow. Perhaps start there and slowly raise the value until you achieve the exact look you are trying to achieve.
Let me know how it turns out -
answered May 28 '14 at 02:05 PM
Lovecraft_K ♦♦ STAFF
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