iRay displacement issue
Wolfschadowe
Posts: 18
I'm seeing an odd rendering error in iRay. It seems to have something to do with displacement. I don't know if it's my settings or what, but if I take the displacement strength of the scalp mat to 1.25, set the minimum to -1.0 and the maximum to 3.0, the "shadow" (It's not actually a shadow" at the hairline disappears...but so does the entire scalp mat and the overall effect is...horrible.
It doesn't appear on texture view, or on a 3dlight render. Only on iRay render or iRay preview. Any ideas how to resolve it?
in this case it's the Sian model, and Udane hair, but it occurs with any Genesis 2 hair that I throw on. Sian model has Genesis 2 Femaile IRay shader conversion, and the hair has iRay uber shader conversion.
Any help is appreciated. I've already spent about 4 hours trying to resolve it through things like dform, scaling, transmap, bumpmap, displacement map, etc...
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Comments
Turn up displacement SubD in the material setting (it's located just below the displacement values). It needs to be higher than 1 for a lot of items.
Thanks for the Tip SickleYield!
It did make a difference to adjust the SubD, but I'm still struggling. I've been futzing with this since about the time you responded and here are the two "Best" I've been able to come up with.
Images are with the Subd set to 3. I've tried higher but it either starts making my computer puke, above 5, or doesn't seem to make a difference above 3. Running a "nice" system with 16GB Ram and single GTX980.
I have displacement at 1, min at -.25, and max at .25 for the one showing forehead corruption.
the other one I've just adjusted min/max until the forehead corruption is gone, but so is the skullcap in places, and the fine transition detail hairs between the forehead and the main hair.
I also played with switching back and forth between black and grey displacement maps, setting minimum at 0 or above zero. Any ideas what else I can tweak? On one hand, it's kind of fun trying to figure this out...on the other, I'm getting pretty frustrated that something that should be this simple...isn't. Or maybe I'm just being dense. :)
P.S. SY, I live and breathe by your DeviantArt tutorials and videos! Thanks so much for those!
You're welcome!
Is smoothing and collision on? It almost looks like it might be a clipping issue.
No smoothing modifier on the hair model. That was my first thought when I started tracking this down. I just added smoothing and it has 0 effect, either modifying smoothing and collision values, or Displacement. I get the same results for both settings as above with smoothing on or off. I also thought transparency at first, but again adjustments there had 0 effect.
The only things that affect the corruption is A) Moving the camera causes it to fade in places, as if glossy or reflection is having something to do with it, but modifying those settings has 0 effect. or B) Modifying displacement settings.
Just thought to include an overall shot. (Stopped at one minute). Lighting is all mesh from the screens/keyboard/LED's.
iRay is so Awesome, I really want to figure this displacement thing out.
Also, SY, I didn't see this on your site, so just in case you didn't know about it. Under Render Settings -> Optimization, there is a drop down to choose Instancing Optimization. Changing this from "Memory" to "Speed" cut my render time in half!
Well, on my Quadro equipped laptop, it made the time longer...but my desktop which has plenty of RAM, it was a significant increase.
I did know about it, and it's on my Twitter. ;) Thanks though, that can't be spread around enough.
I'm doing promo renders right now, so I'm unable to test for the error on my own system as yet. Sorry, I may be able to later today.
So...I'm slowly narrowing things down...I guess.
Loaded the original save, hid everything except the figure, and added an Environment dome, and have a perfect image. (All renders stopped at about 1 minute).
I turned on the Dystopia Console which has all the mesh lights for the second image, and poof, the corruption is back. I have no idea why, or what the cause is. It's not a simple shadow, as it's positioning makes no sense for a shadow.
I guess now I'll start turning the Emitting meshes off one by one to figure out what the culprit is, unless it's all mesh lights in general. Hmmm... So confused. :)
I'm finding it's best to remove displacement from the hair scalps.
Ok. This has got to be a bug. I finally got back to this and tried a default Genesis 2 figure, with the "default" Genesis 2 IRay shader. Pulled in the Sporty Braid. Applied Iray upber base to the hair. Included 1 spotlight in photometric mode. Changed exactly 1 setting to get these three renders (Stopped at about 20 seconds)
Setting changed: Light Geometry.
1. Point - Flawless image.
2. Rectangle or Disc - Sharp shadow image
3. Cylinder or Sphere - Smooth shadow image.
Unless I'm missing something completely obvious about iRay, there should not be this kind of render issue when making that type of change.
Yes, it sounds like a bug. I'm not having that happen.
I sent a bunch of the renders, and the scene file in as a bug report. #192205.
We'll see what happens. I guess there's a chance I'm doing something dumb,
I do appreciate all the help and suggestions! And I learned about the subd thing, which has already improved a couple of my other renders!