I as testing karma and xpu when 20.0 aws out, then had bni a bit busy to keep testing but now trying to make it work again for couple of my project and still running into old issue.
I have character animated in maya, exported as USD and imported in Solaris, added materials and hoping to render it. But I see these artefacts on the mesh. They are not there if I create object nit he H and smooth it, or even if I import this mesh as obj in the scene then move load into Solaris stage. But loading USD like thsi gievs me thsi issue.
I'm thinking that I'm probably doing something wrong either exportin from maya or importing into Solaris.
Any ideas, tip san tricks?
Attached image of the problem nd currently what I'm using to import into stage.

I'd try adding a normal node to the end of the network chain.

No effect. I tried even with SOP Create, then in there USD import, unpack and polygon, and then normal as well. No change

Is this only visible with Karma XPU renders? I remember there being a sample bias bug with environment lights and XPU.

It also looks a little bit like two overlapping meshes.

If it's only XPU and not CPU then most likely a bug. If those artifacts are in both renderers it could be a normals issue maybe. Are those meshes configured to render as subdivision surfaces or (pre-subdivided) polygon meshes? Does the mesh have a "normals" primvar? Like jsmack said it does kind of look like overlapping meshes as well.

I tried exporting from maya again, export with all subdivison options in USD export, none, loop, bilinear, catclark... Now none of them renders smoothed as all. And on top of that rendering CPU still not smoothed but those artifacts are not visible. Rendering with XPU artefacts are there.

Now figured, they are here with dome light,
rendering with karma skylight and artefacts are not there.
Ok found it again. so it is still same bug as it seems s when H20 lunched.
When using HDRI I have to set Maximum HDRI size at something huge like 100000, now artefacts are gone.

Sometimes Maya includes normals in the export that actually cause problems later. I have sometimes fixed this in Solaris by blocking the normals attribute:

1. select any mesh
2. find the 'normals' attribute for this mesh in the scenegraph details panel (I'm assuming it's there)
3. right-click > Edit Properties
4. in the Edit Properties LOP that gets created, switch the control parm to 'block'. (In the scenegraph details panel, the normals attr should now appear grey, with no value)
5. Edit the prim pattern on this Edit Properties LOP so it affects the meshes you want

Basically this should cause the renderer to figure out the normals itself rather than pull them from an attribute.

It's bin a while and I'm still back on this issue even now in H21.
So it seems like exporter from Maya has some issues or.. not sure.
Here is completely diferent character but runnig in what seems to be same issue. I tried exporting with all possible subdivision rules. and even forcing in rendering to catmullClark, and in mesh edit property for subdivision scheme to be catmullClark.. at the end I still have non tessellated meshes at the rendering:



I mean I will probably brute force this somehow, ignore problems and already planning to switch to Houdini full production including rigging and animation as well to skip Maya completely. That will solve this problem, but still have couple shots to render using meshes from maya and was wondering to see what am I missing.

So in short:
export geo from maya
do lookdev in Houdini and save as Character_LDV.usd
Adding layer of anitmaion from maya on top of LDV usd form Houdini.

I will move to Houdini completely already working on rigs for these characters but still hitting my head why is this happening...




EDIT:
Ok this problem solved. I had flat shaded in viewport selected and Karma XPU rendered unsubdivided as well...

But still have this issue of some artifacts when I have all scattered grass turned on, I thought this could be a culprit but it isnt so investigation continue about that other problem. but subd sovled...