Jagged, squared-off shadows on cloth

hadavar

In one week, I've seen this phenomenon twice, each time on different outfits. Some shadows resolve with sharp edges on light-colored clothes. Rather than looking smooth, the shadows are almost pixelated. I've only seen this in scenes where I'm using multiple lights (primarily rectangular lights) with highly contrasting colors.

If you look closely at the shadows on the left side of the dress in my attachment, you'll see what I mean. Lots of sharp corners and edges on the most shadowed portions. Does anybody know what causes this? I'd like to know what sort of settings to avoid.

Thanks.

Paintbox

Subscribing...

hadavar

Glad I'm not the only one!

Which I guess means that misery -- or maybe just minor befuddlement -- loves company.

Sevrin

What garment are you using?  Are they Iray materials?  When looking for help, it's best to provide as much information as possible.

hadavar

Thanks, Sevrin. In the above case, it's the DForce Summer Muse outfit. I've also seen the problem when I use the white coloration of the Basic Corset Lingerie Set. Both are IRay materials. The scenes in which the problem occurs have both involved deep shadows and high contrasts, typically with a golden light for major highlights and a blue to bring out the shadows. The problem shows up in transitional areas between the light and the shadow. I'm attaching an example of it happening on the stockings of the corset outfit.

I run my renders at 100% converged, Quality 1, 15k max samples, Photoreal mode, infinite path length, no Denoiser, Firefly Filter enabled, no Spectral Rendering (the Frankenstein-lines it creates where my models' arms and legs meet their torsos make me twitch), maxed time to render (i.e. I never time out), and typically around 2000 pixels squared.

I'm fairly sure that whatever is causing it would happen no matter the color of the outfit; light colors probably just make the problem actually visible.

rrward

I've had this issue with quite a few items. Changing the lighting can help somewhat as it appears to be an artifact of glancing angles of incident. Though that leg in hadavar's image looks worse than anything I've run into. I haven't tried increasing the subdivision levels on the clothing as I didn't think of it the times I've run into this.

Daventaki

Does bumping your quality up in render settings help any?

hadavar

I think I tried a bump in quality on the lingerie shot, but I may not have. I'll try it, and I'll also see if making any changes to the clothes subdivisions helps. Thanks for the ideas.

hadavar

Rrward, you're a genius! No joy from a quality increase, but the subdivision setting is the fix. I converted the object and bumped subdivisions to 3 (from 1) and the problem is much less noticeable -- dare I say, invisible. Thanks for pointing me in a direction I knew literally nothing about before.

Quickie before and after shot attached.

Sevrin

You might want to soften your lights.