Renderworks problem: flat grey areas appearing

[line-weight]

Is anyone familiar with this sort of thing happening in RW renders?

 

This is in VW2023, using a modified version of "Realistic interior final" RW style.

 

The problem is often first apparent in the preview stage of the render, when it starts looking like this in certain areas

 

 

And the large portions of the final render just end up as a kind of flat lifeless grey, so an area that shoud look like this:

 

 

Looks like this

 

 

 

Sometimes these grey areas appear with a kind of circular edge:

 

 

These black squares often appear too.

 

 

The problem is usually solved by closing & reopening the file, but then it'll usually reappear after a couple of successful renders. This obviously slows everything down greatly.

Edited June 24 by line-weight

[BartHays]

Just a few guesses

 

It looks like you are having sampling or graphics memory issues.

The first three images suggest the sampling quality of Indirect or environmental lighting is too low. 

 

the last image suggests the memory problem where Samples are getting dropped.

I don't know enough about the M1 Mac Mini to understand its specs but it should be more than up to the task. 

 

A) try upping sample quality for longer render times

B) make sure anything else that is using the graphics card is shut down rendering, ( you tube, Chrome browser, - Sometime I even power down my second monitor to give my graphics card more VRAM to work with.)

 

Bart

 

[line-weight]

1 hour ago, BartHays said:

Just a few guesses

 

It looks like you are having sampling or graphics memory issues.

The first three images suggest the sampling quality of Indirect or environmental lighting is too low. 

 

the last image suggests the memory problem where Samples are getting dropped.

I don't know enough about the M1 Mac Mini to understand its specs but it should be more than up to the task. 

 

A) try upping sample quality for longer render times

B) make sure anything else that is using the graphics card is shut down rendering, ( you tube, Chrome browser, - Sometime I even power down my second monitor to give my graphics card more VRAM to work with.)

 

Bart

 

 

Thanks, I'll have a look at what's going on with memory next time it happens (the M1 has a kind of shared RAM/VRAM arrangement).

 

By sampling quality do you mean in the rendering settings? Would a too-low setting here cause inconsistent results though (ie. sometimes it works fine and sometimes it doesn't)?

[BartHays]

I'm not an expert in Indirect/Global Illumination. However, as I understand it, Raytracing (basic RenderWorks) follows a ray from each pixel of the final image back to the light sources. When you add Indirect/Global Illumination, the software casts "rays" from each light source out into the scene and blends those outputs into the Raytracing results. 

 

The Quality settings for Indirect/Global Illumination adjust things like the total number of cast rays, the number of bounces, reflection, and refraction accuracy(collectively "Samples")to calculate.

If you have a ton of lights, each light will cast fewer rays. Lights far from a surface will have those samples spread far apart, so you can get blotchy results or Samples that don't blend well into the raytracing. I assume that the position of the camera affects how many samples it's getting too.  ( ticking the "Use Emitter" on lights gives you more access to control of these settings - but I don't use that much. )
I think this is what you are seeing with the large grey area with the circular edge - It looks like an unblended Sample to me. 

 

If using the same scene, with the same settings, you get different results, then I would lean harder on memory or software bugs.

Re-reading your post, it seems like that is the case. Closing and reopening the file clears it up (for a while) 

Again, just guessing, but it feels like the rendering is running out of memory before it finishes the blending and just craps out what it can.

 

Any chance you can share a file? I'd be curious how you have your lights and materials set up.