Weird Artifact Lines in Iray Render

mikethe3dguy

I have a couple types of lines that are showing up in a render using Photoreal. In the example (Iray preview window screenshot) you'll see:

1. a thin vertical line running down the white tank top
2. yellow lines on the G8F skin in a couple spots

I think these might be unrelated. Both show up in the Iray preview and if I do a full render. For the one on the clothing I've looked through all the texture maps used and see nothing that could cause it. The lines on the skin are much more muted if I do a full render but they're still there. I'm using photometric lights. The yellow lines don't appear if I knock down the walls of my scene, kill the lights and use sun/sky.

Any ideas?

junk

Dang we're approaching a year and still no one is chiming in.  I'm sufferring now and have been for several images now.  I've tried changing the "Render Settings"  under "Optimization" from "Auto" to "Memory" or "Speed" but that works on some images.  Not everyone. It seems that by adding a "Distant Light" I caused my headaches but I really want the super strong sun light in the scene.  I'll try other methods and see if it works.

TheKD

I have seen that using the spectral rendering option can make some weird seems like that.

DireWorks

TheKD said:

I have seen that using the spectral rendering option can make some weird seems like that.

never seen something like that but with spectral enabled, translucency with scatter and transmit on characters usually gives arctifacts along the UV seems, maybe it depends from the textures, the normal textures or textures with not enoough border

are the tattoos applied as LIE?

 

junk

So it seems that "Distant Lights" causes the problem at least in iray.  If you create a plane or sphere or whatever and apply an "emitter" surface to it you can resolve the problem.  Basically make a softer light and just make sure you make it strong enough.

The attached image shows the difference between the two.  Between scene's I was playing with moving the light around so the direction of the light is slightly different between the two.

Here's the finished image:  https://www.daz3d.com/gallery/images/985621/

Sevrin

junk said:

So it seems that "Distant Lights" causes the problem at least in iray.  If you create a plane or sphere or whatever and apply an "emitter" surface to it you can resolve the problem.  Basically make a softer light and just make sure you make it strong enough.

The attached image shows the difference between the two.  Between scene's I was playing with moving the light around so the direction of the light is slightly different between the two.

Here's the finished image:  https://www.daz3d.com/gallery/images/985621/

It's for sure something to do with lighting and reflections from the skin.  I had a situation where I got artifacts on the forehead, as if the cap didn't fit, but when I changed angle, the artifacts disappeared. 

mikethe3dguy

Of course my OP was a while ago, but I never found a solution. It wasn't distant lights in my case, as I didn't use them. I fixed it in post. But now I'm having a similar issue on one article of clothing only. No distant lights, just emissives, spotlights and an HDRI through the window. Tried eliminating each light type in turn and it hasn't made any difference. Spectral Rendering is OFF as it is for all my renders.

fakebrush_2ce9b32c93

mikethe3dguy said:

Of course my OP was a while ago, but I never found a solution. It wasn't distant lights in my case, as I didn't use them. I fixed it in post. But now I'm having a similar issue on one article of clothing only. No distant lights, just emissives, spotlights and an HDRI through the window. Tried eliminating each light type in turn and it hasn't made any difference. Spectral Rendering is OFF as it is for all my renders.

 

Having the same issue. i tried everything. the only time it disappears is when i apply a different skin material preset than the one i want to use. so i'm assuming it is this. all other factors were replaced  when i tested, ie. hdri maps, geoshells, LIES, etc,.

mikethe3dguy

Having the same issue. i tried everything. the only time it disappears is when i apply a different skin material preset than the one i want to use. so i'm assuming it is this. all other factors were replaced  when i tested, ie. hdri maps, geoshells, LIES, etc,.

Wish I could help, but I only ever saw that issue come up in one render. Plus it looks like my example images have vanished from the OP so I don't even have a clear idea of which render it was. Good luck!

Sevrin

fakebrush_2ce9b32c93 said:

mikethe3dguy said:

Of course my OP was a while ago, but I never found a solution. It wasn't distant lights in my case, as I didn't use them. I fixed it in post. But now I'm having a similar issue on one article of clothing only. No distant lights, just emissives, spotlights and an HDRI through the window. Tried eliminating each light type in turn and it hasn't made any difference. Spectral Rendering is OFF as it is for all my renders.

 

Having the same issue. i tried everything. the only time it disappears is when i apply a different skin material preset than the one i want to use. so i'm assuming it is this. all other factors were replaced  when i tested, ie. hdri maps, geoshells, LIES, etc,.

The way to find out what's causing the issue is not to change everything, but to change one thing, test render, and check.  If the problem is solved, that was the issue.  If not, revert that change, and change something else.