Problem With Hair Shadow
Simsalabim
Posts: 34
Hi there
I experienced some problems with shadows when using Lindays Soft Classic Hair (https://www.daz3d.com/soft-classic-hair-with-dforce-for-genesis-8-and-81-females).
The single thin hairs cast a weird and wide shadow on her face, as seen in this image:
When I hide the items, the shadow is gone and it looks like this:
When I turn Opacity to 0, the hair isn' visible anymore, but the weird shadow remains:
I tried different Opacity maps but the shadow doesn't change. Also slightly changing the sizes had no effect.
I also tried exporting it and import it as a new obj file, but the result was the same.
Anybody know why this is, if and how this can be fixed?!
Preferrably with a natural shadow, or if not then at least have no weird shadow at all.
Cheers and thx in advance!
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Comments
This is Iray?
Yes
Looking over the product decription, it says it uses Geoshells, which is...unusual when it comes to hair. I'm wondering if there's some kind of opacity issue with the geoshell? Try looking at the properties for the Geoshell itself. The offset, the material zones it's affecting, etc.
How are you getting the hair into that postion?
Tried playing with the offset...nothing. Also what's weird is that when I edit the opacity to 0 so it should be invisible, the hair disappears but the shadow remains.
dforce
I didn't get the strands to separate like that, what starting shape etc. are you using?
Just standard wavy 07.
But she's turning in the simulation so the hair falls over her face.
I'm wondering if it maybe uses some kind of Light Path Expression sorcery, but that's way above my skill level.
Does it go away if you use a different skin? I can't get the hair to produce simmilar results, though the drape is rather different, on a Genesis 8 Female base - I used scene lights, the default HDR, and Sun/Sky.
There is a bug with opacity in the latest Studio releases, where 0% opacity isn't really 100% transparent. This mostly causes issues with volumetric props, but also when you have multiple transparent layers, which Soft Classic Hair has.
You can test this by placing 20 transparent Primitive Planes one after another and shine a light through them. The 21st transparent object (primitive, prop, character...) the light goes through will cast a shadow.
I kind of like this bug. A lot of possibilities for rendering.
Richard, did you try to set opacity for hair to 0%?
No, different skin doesn't help.
But there's also a weird shadow if I only use one of the layers and hide the others...?!
If you remove opacity maps or switch to Lit Wireframe in Viewport you will see that the hair has a buttload of geometry. Even individual parts have so much "geometry layers" the light has to travel through that the bug I mentioned above kicks in.
I don't know of any way to circumvent the shadow issue. We will probably have to wait for nvidia or DAZ to fix it.
Necromancy time!
I encountered this issue with SU Medium Length Hair. It's a geometry layers vs Max Path Length issue - iray is terminating the ray length early, resulting in shadow.
Setting max path length to a specific number, rather than -1 (which isn't really infinite - iray decides, incorrectly in this case). In the examples attached, I set it to -1, 64 and 128 respectively.
The first and last images, with hair at default opacity and at -1 and 64 max path length, are ever so slightly different (-1 hair is slightly darker around the edges), but probably not to the extent that a problem should arise in a final render.
Encountered this issue myself, using 4.16.03; increasing Max Path Length to 64 resolves it, but creates a whole other set of issues for rendering. Total bummer.