Strange shadows with use of Corona sun

[dia]

We getting strange shadows when using Corona sun .The objects it effects is highpoly objects and not lowpoly as it looks like. Something somebody else have ?

[FrostKiwi]

Could be three things from my point of view.
Obvious first: Terminator bug, shadowlines and blocks with strong bump and low poly:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000516258-objects-in-my-rendering-are-not-smooth-faceted-and-i-can-see-shadows-of-polygons-
High poly is a subjektive thing, apply grey Corona Material and slap a turbosmooth on top to check.

If you use Normal maps, they could be inverted on some channel, like the usually needed green swap, has made line artifacts for me before.

Wrong smoothing groups. Apply new smooth modifier with smoothgroup 1, to See if that is the Problem, won't so anything if it is not.

[dia]

Could be three things from my point of view.
Obvious first: Terminator bug, shadowlines and blocks with strong bump and low poly:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000516258-objects-in-my-rendering-are-not-smooth-faceted-and-i-can-see-shadows-of-polygons-
High poly is a subjektive thing, apply grey Corona Material and slap a turbosmooth on top to check.

If you use Normal maps, they could be inverted on some channel, like the usually needed green swap, has made line artifacts for me before.

Wrong smoothing groups. Apply new smooth modifier with smoothgroup 1, to See if that is the Problem, won't so anything if it is not.

The bumpmap was the problem in the first image. I havent checked the others yet but clearly to "strong" bumpmap causes polygon artifacts in the shadows. The object it self wasnt low poly and was smooth and fine...

Thx!

[Juraj]

1st and 3rd is definitely 'terminator'. I deal with by using Turbosmooth on every organic fabric model with strong bump (or any bump at all...). I set the TS to 0 in viewport to not hog performance but 2-3 in render time depending on density. That might also give me astronomically dense poly mesh on verge of displacement, but what else to do.

The middle one could be refraction issue. If the light falling on the item goes through refractive surface and the object has glossy reflection (which every object has...) it might cause another artifact. Solution is 'thin' glass without refraction, or refractive glass in RaySwitch material with Thin mode in GI mode override.

These two are quite workflow killer, hopefully there will be solution to them eventually.

[romullus]

Just wait for 1.5: https://trello.com/c/0wsCG5EM/49-bug-fixes :]

[Ondra]

Combo of terminator (hopefully will be fixed soon) and black highlight problem (now fixed)

[drvoxx]

I had the same issue only when using a background with rayswitch material. If I hide that background object sun shadows problem is gone.