Unity does unwanted shadow cascade culling

[Kuura]

I’m trying to do some basic blending between Unity’s shadow cascades because by default they have this sharp seam which doesn’t look very nice.

I succeeded in implementing some blending by modifying the screenspace shadows shader and the results so far look promising. However, Unity does automatic culling of small objects for further cascades, causing objects to disappear from the cascades before the blending between them finishes. This makes implementing any sort of cascade blending impossible without causing problems with shadows popping in during blending.

Here’s an example. The top picture has the shadowmap of a scene containing a single cube with 4 cascades. We can see that the cube exists in 2 of the cascades and we can blend between these nicely.

Moving the camera slightly we can notice the cube disappears from the further cascade. When using blending, this causes the shadow to pop out of existence before it should.

Is there anything that could be done about this?

Edit: Some wording changes, lol.

[tomaszek]

Necro thread, but it apparently can happen also within most recent Unity versions. It’s something about too aggressive shadow casters culling. The only workaround I found is to increase manually bounding box of an object to force Unity “thinks” it’s still visible even though it might get a bit out of frustum (of drawing camera as well as shadowmap “camera”).