Completely Black Render: What's Happening?

LenioTG

Hi everyone!

Recently, it's happening to me a lot to get a completely black render, after a few seconds of rendering.
If I start it again right away, it falls back to the CPU.

Sometimes, if I move the render window preview, some parts end up being darker.

I don't recall it happening in the previous Daz builds, but now I get this either in the stable one and in the public build.

Any solution on the horizon?

mclaugh

Possibly a driver issue, but I see that all the time when I run out of vRAM. (DS holds onto a chunk of vRAM after rendering (or if you do an iRay preview then try to render), so every render leaves less vRAM available for the next render. When a new render won't fit in the available vRAM, DS either falls immediately to CPU or throws up a black screen.)

One way of forcing DS to completely clear vRAM (at least on my rig) is to switch render modes between GPU-only and GPU+CPU. YMMV. The other option is to quit and restart DS.

LenioTG

mclaugh said:

Possibly a driver issue, but I see that all the time when I run out of vRAM. (DS holds onto a chunk of vRAM after rendering (or if you do an iRay preview then try to render), so every render leaves less vRAM available for the next render. When a new render won't fit in the available vRAM, DS either falls immediately to CPU or throws up a black screen.)

One way of forcing DS to completely clear vRAM (at least on my rig) is to switch render modes between GPU-only and GPU+CPU. YMMV. The other option is to quit and restart DS.

I didn't know that trick of switching between modes, thank you! :)

mclaugh

You're welcome.

I stumbled on it when I was trying to figure out why DS sometimes wouldn't render in iRay at all (not even a black screen: just an empty window). Eventually, I discovered iRay would render if I switched to OpenGL, ran a render, and switched back to iRay, but not if I switched to 3DL and back. That was the tipoff that it was a vRAM caching issue.

When I started getting the black renders, I started experimenting with GPU-only and GPU+CPU, and discovered that the problem went away if I (remember to) switch modes between renders. (I should note that I have to switch modes before rendering if I open an iRay preview viewport.) As I said, YMMV.