Unacceptable Black Smears on Characters Skin
Patroklos
Posts: 533
This is the second time I have had this problem, rendering using Iray & lighting with Iray HDR Outdoors I get black smears, a bit like tar oil appearing at random. Replacing the mats makes no difference, and deleting and undeleting the character makes no difference.
It shows up on the Iray preview, but not on texture shaded. Anyone else seen this? Any ideas?
This makes the whole Daz program useless.
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No problem showing on a quick 3delight render.
Using Iray Interactive (as opposed to Photoreal) the marks disappear after a short while - like burn off.
B
Please show a picture, with the figure clothed or cropped to show only the head or limbs if the problem shows there.
Your settings would also help.Since hundreds of Iray renders have been posted without this issue, it would seem likely that there is an issue in your setup or installation rather than a general Studio problem.
Is it snything like what is described here?
I have seen that problem, but not this time.
ok
last
Do a search for 'shadow terminator artifact,' on Google and here. It's a known problem of all unbiased renderers.
The general fixes are:
1. Move your lights, use softer lights.
2. Increase the SubD level of your model.
3. Fiddle with any displacement maps for the textures.
Hello & thank you. I have seen this problem, and the only way that I have found to deal with it is to increase the SubD level if possible.
However the problem that I am experiencing is quite different and does not occur at the edge of shadows, but randomly on the exposed area of a characters' skin.
As part of my experimenting to overcome this problem, I am using Iray Interactive where, as I mention above, the problem does not occur. I am able to get good results, however the transition between light and shade is very sudden using default settings. Does anyone here know what setting I should use to soften the transition between shade and light.
Is that the render or the preview? It looks to me more like a UV seam issue, as if the wrong UV Set is selected, but the image is too small to have any confidence.
I have seen the issue that you describe previously, and this is certainly not that issue.
Here is a better picture
Another. It is not near a dark to light interface.
You are using the latest version of DS - 4.8.0.59? It doesn't really look like the shadow terminator issue, as it isn't on the termininator. It does look like something weird with the normal, or possibly bump, maps and I'm wondering if it's a compression issue - which I thought was avoided (by not compressing normal maps) in the latest build. I don't know where the second new image is on the body, but it doesn't look as much like a seam as the earlier images.
Nevertheless they are likely shadow artifacts if using Iray Interactive gets rid of them. That engine does not use the same shadow physics as the Photoreal engine. While not on the terminator per se, shadowing is still performed across the full surface.
I don't know what 'Iray HDR Outdoors' is (a product?), but try a different HDR image, preferably without any additional scene lighting. The default HDR "Ruins" image is a good one, because its main light source is not overly distinct. Work yourself back up to all the lighting until the problem reappears.
On edit: As you noted, you're still using a beta version. So I'd update first, then try the other potential fixes.
I am on 4.8.0.56 I will update. Long image is rear leg, other is lower right back.
What you say is interesting, so thank you for coming back to me. I have rotated the character with the problem by 5 deg. and the nature of the mark has completely changed.
I am using the MauiA HDR with no other lighting. That being the case what changes to lighting is it possible to make?
I thought it updated automatically? Nothing is happening. How do I make it update?
OK, it seems I had 2 versions on my machine, I now have the correct one only.
I have to go now, hopefully the new version and the insight given me by Tobor will allow me to sort the problem out.
Thanks for help.
Back of the leg and lower back could be the seams - I still ssupect compression of the normal maps causing issues at the seams, where the background colour gets mixed in, in which case the switch to the newer version should help.
Just using the release software may fix it, as Richard says, it might be a glitch in how normal maps were handled in the beta versions. I don't have many characters with normal maps -- just bump and sometimes displacement -- so I never saw this during the beta test.
The triangle shapes on the surface, which are from the underlying mesh, suggest it's a shadowing defect. This comes from under-tessellation, which is why upping the SubD or modifying the settings of any height maps can alter the appearance of the dark areas. Though it's often referred to as shadow terminator artifact, there is shadowing going on across the entire surface, not just the shadow bioundary. So will the defect is mostly observed at the boundary, it can happen other places, too. I suppose it goes by a different name then, but the "fixes" are the more or less the same.
Since you're using an HDRi, you can also try playing with the dome rotation. That's a hassle though, and it alters the direction of the shadows you do want. So the best route is to tackle the problem as noted above. My money is on the problem disappearing with the .59 version of D|S.
I'm getting something very similar happening on my renders.
Black triangle-shaped smudges that appear in a constant places on the figure.
Moving the camera and the sun-sky light source does not change the appearance.
Using local spotlights instead of the sun-sky done does nothing.
If I repose the character, the problem "moves" as you can see in the third image.
Interestingly, the flaw survives substtuting a NEW old-school 3Delight skin material (fourth image)
I am using DS 4.9.1.30 on an nVidia. Drivers are up to date
I recently reported some similar looking artifacts in the PTH set form DAZ. See attached Iray image. Moving the "sand" mesh did not change the artifact so I assumed there was an issue with the mesh. I have not yet heard back from the helpdesk on this issue. I was using DS4.9.1.30 for this image. I just rerendered in DS4.9.2.55 and the artifact is still there.
All of those are renders?
Which figure/character?
And does the problem survive if you change to "Base" under the resolution in the Parameters?
Is the texture for the sand tiled?
That looks like bad seam matching to me...
Hi mjc1016,
I don't think the texture is tiled (see attached image). The texture is large, about 4kx4k pixels, although the resolution is not that high.
Not tiled...the way the edge looked, it looks a lot like the "padding" often on the edges of textures that can show up if the map is tiled and really shouldn't be.
I assume the Vertical tiling =1 and horrizontal tiling =1 (as shown in the screenshot) does mean that there is no tiling applied.