Issue with texture banding on iray GPU :(

grimulkan_9cfbd329bc

I loaded Fern Lake (iray) with default render settings and rendered over CPU (top figure) then GPU (RTX Titan, bottom figure).

What's with the banding on the water on the GPU? I see it on 4.12 non-beta DAZ studio as well as the latest beta (4.12.1.76), in both iray preview and final render views. I've tried messing with UV tiling and texture compression but it doesn't change the banding pattern. Anyone else see this?

I've seen it happen in a few other scenes, but always blamed myself for incorrect render settings or materials. But this time I bothered to check with a CPU render and it seems fine.

ParallaxCreates

I'd dare say it may be the the Nvidia drivers you have installed. Maybe do a clean install using DDU as well.

https://www.guru3d.com/files-details/display-driver-uninstaller-download.html

grimulkan_9cfbd329bc

I guess that means it is not supposed to happen? That's mainly what I'm trying to find out.

Worth a shot re-installing drivers, will give it a try. Thanks.

dijitul

This is just a shot in the dark but sometimes if you have evironment "ground" turned on in the Render Settings and you also have a plane set to zero Y-axis, they overlap and cause random faces to poke through.  Remove one of those items.  It may also happen if there are two planes overlapping (e.g. one for sand, one for water), so one of them may need to be offset by just a little bit.  There's also the possiblity the "normals" are not facing the correct and consistent direction.  Again, just guesses.  

grimulkan_9cfbd329bc

Thanks. Reinstalling drivers didn't do anything, nor did messing with environment ground settings or looking for overlapping planes.

But bingo on the normals! The issue goes away if I set Normal Map to 0.0. The size of the visible "tiles" are inversely proportional to the normal map amount.

Still strange that the CPU render does not show the problem. The normal map itself does look right and looks like it should tile seamlessly too (it's from Stonemason).

dijitul

If adjusting the normals map amout affects it, then it's possible the surfact texture UV mapping isn't set up very well or that the normal map texture itself is not created very well.  Was there a UV map assigned to the node?

Stonemason

sorry I thought this was fixed a long time ago.it's actualy as mentioned above a z-fighting issue,the easiest fix is to just raise or lower the water plane.doesnt matter by how much.even a millimeter should fix it.

grimulkan_9cfbd329bc

Thanks to Stonemason and others!

UV and the normal texture does look right to my eyes (and renders fine on CPU). Setting normal amount to anything other than 0.0 brings out the pattern (the more the amount, the smaller the "tiles").

Changing the vertical position of the water (the fpsWater object) helps. However, the extent to which it is raised does matter, depending on the angle and distance of the camera. I need to Y translate the water a lot (> 20 units) before the banding disappears at all reasonable angles. At smaller values, I can still produce the banding at certain angles (egs., like the one in my original screenshot).

But with these 2 fixes I can work with it. Thanks!