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Thread: brightness of mesh under feet less than when it is overhead?

  1. #1

    brightness of mesh under feet less than when it is overhead?

    Simple white rectangular tiles with a faint grey marble effect (static meshes). When placed as a floor (with 8 units empty on each side) they look pretty grey. However, the same tiles are the ceiling and they look white. I have lights 64 units from floor but 212 from ceiling! There are no other lights, no 2 sided textures. I can't figure it out, when on the floor these white tiles look grey even when hovering around. Place them as a ceiling and they look white? Any ideas why illumination seems directional?

  2. #2
    Theyre not set to special lit or something, right? hmmm

  3. #3
    What texture?
    If it is a Shader with Specular, then it could be your camera angle to the surface.

    Also don't forget that lights change their "hot" light location depending on their radius and the distance from surfaces. You can see this as you move lights in real-time. It is even possible to get lights that have a dark hotspot depending on their light-to-surface distance.
    So a "closer" light doesn't mean that it is brighter.

  4. #4
    This texture is nothing special, just a tileable of white marble I made using GIMP and compressed to DXT1, no speciallit, etc except I do have levelinfo lighting set at 16. I've seen the hotspots get dark too, I'll try moving the lights around some more and post a screenshot when I get the time. In the meantime I've set it to unlit but I'd rather have some shadows too!

  5. #5
    Well here is the result of my experiment. On the Left are static meshes on the right BSP. The lights are 64 units from ceiling and 128 units from the floor. Radius doesn't seem to matter with this as the first and last lights are radius 16 while the middle radius is 64. Conclusion: closer than 128 units, the brightness falls the closer the light get to the surface, farther than 128 units the brightness falls the farther the light gets from the surface. I didn't experiment with bigger lights, the fall off may occure at a different point as the radius increases.

  6. #6
    Lights are normally not set so bright as to oversaturate as they are in this image.

    Also, StaticMeshes are lit per-vertex, so the distance from the light source to the face vertices is what matters, along with brightness etc. In other words, if the StaticMesh is a large cube with no tesselation (ie. only 12 total triangles), it will never light with a hotspot near the light when the light is set in the center of the cube.
    A CSG cube will show a hotspot, since it is using lightmaps.
    It is very easy to see this effect in the screenshot, as the CSG cubes on the upper right have a hotspot that gradiates darker towards the edge, while the StaticMeshes on the upper left have flat lighting across the faces that are towards the lights.

    A person will also notice that as the light is moved closer to the surface, it dims and then goes black once it intersects.
    Which is why a light closer to a surface may not light as bright as when it is a further distance from the surface.

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