Render resets and refuses to converge; especially with spotlights

notenoughtime

Hello there. I have attached an image (or will attach, if this file ever uploads) that I allowed to render for 37 hours before I finally stopped it. When I looked back at the history, it appeared that the convergence and render iteration had reset several times, with the most recent one stopping at iteration 180 before going back to 1. I also had an issue with spotlights in this render, which I've had previously as well: areas that are hit with light from a spotlight seem to have a really difficult time rendering, moreso than surrounding areas. Spotlight areas get filled with lots of white dots, while areas that are lit by ghost lights or hdri do not seem to have this issue. You can see some of this in the attached image. Does anyone have any ideas for what's going on here, and how to fix it? My computer isn't the best out there, but it's not the worst either, and I've rendered more complex scenes than this before without this issue. Most renders (full scenes) finish within a couple of hours on my computer.  

The log is filled with this message between rendering messages:

"2022-03-23 14:36:27.756 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(367): Iray [ERROR] - IRAY:RENDER ::   1.12  IRAY   rend error: OptiX Prime error (Device rtpModelUpdate BL): Memory allocation failed (Function "_rtpModelUpdate" caught exception: Encountered a CUDA error: cudaMalloc(&ptr, size) returned (2): out of memory)
2022-03-23 14:36:27.757 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(367): Iray [ERROR] - IRAY:RENDER ::   1.6   IRAY   rend error: CUDA device 0 (NVIDIA GeForce GTX 1080 Ti): Scene setup failed
2022-03-23 14:36:27.757 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(367): Iray [ERROR] - IRAY:RENDER ::   1.6   IRAY   rend error: CUDA device 0 (NVIDIA GeForce GTX 1080 Ti): Device failed while rendering
2022-03-23 14:36:27.757 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(367): Iray [WARNING] - IRAY:RENDER ::   1.6   IRAY   rend warn : CUDA device 0 (NVIDIA GeForce GTX 1080 Ti) ran out of memory and is temporarily unavailable for rendering.
2022-03-23 14:36:27.784 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(367): Iray [WARNING] - IRAY:RENDER ::   1.6   IRAY   rend warn : All available GPUs failed.
2022-03-23 14:36:27.784 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(367): Iray [WARNING] - IRAY:RENDER ::   1.6   IRAY   rend warn : No devices activated. Enabling CPU fallback.
2022-03-23 14:36:27.784 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(367): Iray [ERROR] - IRAY:RENDER ::   1.6   IRAY   rend error: All workers failed: aborting render"

It goes on to log that it's rendering with CPU, before eventually displaying the same error. Maybe I just need a new computer, but I feel like there's something more going on here at the very least with the spotlights. 

I appreciate any help that anyone can give!  

Edit: It's not letting me upload the picture at the moment, but I'll keep checking back to try and get it to work.

felis

My guess would be that you are running out of memory.

Can you render a simple scene?

notenoughtime

Thank you for your response! Yes, I can render a simple scene, and the spotlights don't seem to have the same problem when the scene is simple like that. 

felis

It is often many high resolution textures there is eating up memeory.

In render settings, Advanced, you can try to lower thresholds values for texture compression and see if it does you can render. Low values (higher compression) can cause artifacts, but then you at least know what the problem is.

There are also some products at Daz that can help with that such as https://www.daz3d.com/scene-optimizer

 

notenoughtime

Hm, thanks for you insight. I tried modifying the texture compression values and didn't see an impact. I also tried creating a new scene and adding tons of high resolution characters, environments, and clothing in an attempt to induce the problem, but didn't have luck there either (my computer got slower, but it didn't cause any artifacts with spotlights). I've got scene optimizer, though, so I'll try that and see if it has an impact. 

Edit: I'm not sure about the render resetting itself, but the weird spotlight artifacts are still there after running scene optimizer. 

Edit: Nope, the render is still resetting itself. 

notenoughtime

Since it won't seem to let me upload anything on the forum, here's a link to the image: Myra history (in progress) by pseudomonasaur on DeviantArt

You can see in the image that everywhere the spotlight hits (try looking at her face) it seems to have trouble. 

notenoughtime

I FIGURED IT OUT. At least, partially. The strange lighting artifacts are caused when I have both a spotlight and a ghost light in the same scene. I haven't done tests to see if it goes away when it's a simple enough scene, but in a complicated scene if you remove all the ghost lights OR all non-ghost lights, then the effect goes away. But have them both in the same scene, and the spotlights misbehave. It's a little strange though; if I can consistently reproduce the issue on my machine, why isn't anyone else having this problem?

Spacious

What version of DAZ is this happening with?  If it's 4.20.02 then this is a known issue, although there seems to be no agreement about what is causing it.  It seems to have something to do with a change in the Iray render engine and how it choses to render on GPU or CPU and when it decides to switch.  I've been setting the render settings to use CPU only, and unchecking GPU, when it's too big a scene to render on GPU anyway.  That has "fixed" it for me, maybe that can help you.

notenoughtime

Thank you for your comment! I am indeed using version 4.20.02. That's a good idea for potentially fixing the render resetting itself, at least for the more complicated renders. I'd already made several renders since the update, but hadn't noticed anything like this since they were simpler scenes and finished more quickly. 

Is the spotlight & ghostlight thing a known issue as well? I did run a test with a more simple scene, and I only got the problem to reoccur when I used a complicated environment alongside the spotlight and ghostlight. But it consitently goes away if you only have one or the other in the scene.

 

 

 

 

FSMCDesigns

I never use spotlights, they always seem to take the longest to converge and are usually too harsh. I stick with point lights and emissive planes the most.

Gordig

Maybe it's just my natural contrarianism, but I've found emissives very frustrating to use as actual light sources, and abandoned them for point lights and spotlights.