Catwalk wire mesh causing severe lightmap aliasing

I have a catwalk outside of a water tower model that’s casting shadows on the side of the water tank. As you can see in the picture, the shadow is severely aliased producing a hideous mosaic pattern instead of a more realistic shadow. I know I can turn up the resolution of the lightmap, but it gets enormous by the time the problem goes away. Is this a work-around for this?

Adjust the Light Source Angle of the directional light, that will cause the shadows to blur more the further they get, that might make the shadows look more clean.


I think what you’re really looking for is Cascading Shadow Mapping! You can get crisp sharp accurate shadows without using huge resolution lightmaps!

I tried both the Light Source Angle and the Cascading Shadow Mapping. Increasing the Source Angle helped somewhat. But the Cascading Shadow Mapping does look a lot better. However, turning on the Cascading Shadow Mapping seems to do bad things with the phong shading. The poly faces are no longer smoothed. It’s not terrible. But it is noticeable.

You can separate parts of the mesh to have the wires cast dynamic shadows, but bake the rest. And use a blueprint to assemble it into one object.

The faceting is a shadow bias issue, you can adjust that value, or use more geometry to get smoother shading.