Shadow leaks.

Hi. I have these artifacts all the time:

This is shadow leaking apparently due to bilinear interpolation between black shadow and light. The right column is submerged on the given image. On the left column, the shadow is leaking from under the column. These leaks are everywhere. Will this be fixed in the new light mapper or in general? I know it's not that easy to understand which way to compensate for these leaks and which side is invisible, but I think this is solvable and configurable. For example, one could place some sort of markers and volumes to designate visible volumes. Or it could be done based on light probe positions.

In this case, those are shadow leaks, but the light is leaking the same way. The lighmapper needs to be aware of the scene elements visibility so it can remove the leaks by extrapolating visible texels.

 

The attachment is not working so it's hard to understand what you're talking about.

 

Oops, sorry about that, I reuploaded the image.

 

Actually it does that (it rejects texels that it considers to be in intersecting geometry). That's assuming you have the default backface tolerance value, and you haven't set those materials as double sided GI.

 

I'm using a plugin lightmapper that has these issues solved, however it has some of it's own (much fewer artifacts though)

But this has to be fixed in builtin tools.

 

It doesn't do it properly. It discards only one texel but it should discard 2, otherwise, the interpolation between the discarded texel and the next one will show as this leak.

 

What back face tolerance value are you using?

Is this a test scene? Can you share? I'd like to investigate.

 

Unity discards the texel 1, and as you can imagine if the texel 2 is black then half of the texel one will be a light to black gradient and it will result in a visible artifact.

This light mapper discards 2 texels so that interpolation between texel 3 and 2 is not visible from above the surface in this case.

 

I used every value of backface tolerance.

 

Hm.. Actually, I think I was wrong. This is the scene with point filtered lightmaps. The texels are not discarded as if backface tolerance not working at all.

This is backface tolerance = 1:



This is backface tolerance = 0;



I'm skipping the filtering step there, I assume it only does the blur, and I don't want it if I want to see what's going on.

This is progressive lightmapper. Same results on the Default Medium setting.

Tried maximum pushoff (1), no difference.

 

With these settings absolutely the same result.

 

@AcidArrow I uploaded a scene, although there is nothing unusual about the scene. The geometry used there is not optimal, but I keep it that way to test how it would behave with some modular assets I plan to use. https://drive.google.com/open?id=1fEinyiZU9ZStuvIPDMryGi4EapQvSwhj

Requires Probuilder.

 

@illinar Are you sure you don't have double sided global illumination enabled in your materials? It seems to work fine for me. Can you double check?

Here is the scene with double sided global illumination OFF on the materials:

(looks pretty clean)

And here is the same thing with double sided GI ON (didn't bother to finish the bake)



It looks similar to what you're seeing, which makes me think that you have double sided GI on, which effectively disables texel rejection.

 

Yes, thank you, I didn't know about that setting, it solves all those issues. It doesn't completely solve only the "box on the ground" problem (front face to front face) but that should be possible to avoid hopefully.

 

For anyone else who has similar issues like this, you can also increase Packing Margin by a lot in model Lightmap UV settings, and you should optimise by cutting a hole in the floor and welding where the pillars are.

 

This wasn't really relevant in this specific instance.

 

"and you should optimise by cutting a hole in the floor and welding where the pillars are" Hmm, why though? It doesn't save lightmap resolution since the lightmapper won't put anything into those holes anyway. Overdraw shouldn't be an issue since I will make sure that the floor and the ceiling are on a separate mesh, or all the objects in the center of the room are. Only thing it would do is make the direct baked shadow contact a bit better.

And I might be polycount bound on mobile VR.

 

At the expense of more vertices you would have eliminated the need for texel rejection. That's all.