Ray traced DF shadow black line artifact on landscape

Development World Creation
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1

For some reason ray traced distance field shadows produce this weird black line along the termination distance of the shadows. It doesn’t seem to be affected by either skylight nor the dominant directional light settings, other than the directional light’s DF distance setting.

With DF shadows: http://i.imgur.com/5VvZjUB.png

Without DF shadows: http://i.imgur.com/mAFKex1.png

2

This is still a problem in 4.18.

https://i.imgur.com/CIKUekx.png

https://i.imgur.com/OYCqx4H.png

https://i.imgur.com/aLtmtMs.png

Edit: I just noticed that it’s somehow related to the far shadows. Far shadow cascade amount is at 1 and setting it to 0 causes the problem to disappear. Increasing cascade count to 2 helps too somewhat, but it’s still there.

Edit 2: From a shallow angle (as in when you’re standing on the landscape) the problem persists even without far shadows. From a high angle it disappears if I turn off far shadows.

Edit 3: There are also black outlines on landscape against sky and landscape geometry that occur after the distance of the DF shadows:

https://i.imgur.com/R9PMxEs.png vs https://i.imgur.com/Z8gAptj.png

3

Right, still a problem and I think it’s somehow related to the fact that distance fields aren’t ran at full resolution. If I use r.DFFullResolution 1 the problem goes away but performance tanks quite a bit.

4

I’m seeing this issue in 4.20 as well, I’m seeing it after organizing my levels in a level streaming hierarchy. Previously I have not had this issue, in 4.20 or any other version.