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Hi there,
I'll preface this by saying that I've been working with VRay next and now VRay 5. I'm hoping to have a general discussion with some of you who have been rendering animation with VRay GPU. I've been doing some arch viz with VRay for a few years so if my thinking and methods and understanding on this has holes feel free to point them out, I'm no expert. I approach using VRay with more of an artist brain than a technician, so it's kind of free form to find what works for a particular project. I've slowly learned more and more about what is technically needed to render a good animation, and here are a few things I've noticed about the different approaches. I'll share a few things I've learned about working with VRay GPU, which you might find helpful or if there are solutions and things I haven't thought of, please let me know.
With Light Cache, it is great for stills, but I can't seem to understand why it is recommended for animation. On the recommended settings, (now default for animation) of 3000 LC subdivisions and 8 retrace, It is extremely likely that some of your frames will have "unhandled exception errors." These errors will occur randomly, there is very little you can do to anticipate when these will happen, which I guess is just the nature of data going in and our of GPUs. 95% of my animation shots that I've attempted to render on light cache, have taken a super long time to finish because some frames simply won't render correctly in sequence. I've read in a few places that the way GPU's prepare the data for rendering is sometimes prone to error, and when something is not loaded in correctly it will produce these unhandled exceptions and crash the frame, and move on to the next frame where it may or may not happen again, depending on how the data loads into the GPU for that frame. When this does happen, I've noticed that it can be useful to run garbage collection, "gc()" in max script, and "freescenebitmaps()," to purge the bloat in your scene and load in your bitmap textures fresh. This usually fixes issues on those occasional problem frames. I'm rendering with Hybrid CUDA, cpu and gpus (Threadripper 2950x, 2X 2080TI). Maybe LC is more stable on strictly GPU? I'd love to know of what setups have worked for you with LC on what kinds of projects.
Knowing these pain points with Light Cache, I've been rendering more often with Brute Force for GI, and while it's noisier, it is WAY less prone to error. Sometimes some frames have a problem here and there, a few flickers that can be easily fixed, unhandled exceptions can still occur, however way less frequently, and re-rendering those frames almost always works like a charm. Flickers from LC are also so much more significant, sometimes the global illumination can vary WILDLY frame one frame to the next, that you usually cannot simply fix those issues in PS or AE or whatever. Flickers from LC almost always re-produce when you try to re-render these problem frames too, so you can't simply re-render them a lot of the time, which likely means you need to re-render the entire animation if you changes the render settings. In a LC animation I can have up to 25% of frames with errors. With Brute Force it is down to 5%. I've also noticed that generally on my rig, Brute Force achieves a lower noise threshold faster than LC, as LC takes a pre-render calculation done on CPU, which is factored into total render time. So I'm sort of wondering why is LC recommended for animation? Brute Force does have a few caveats though, in that when it crashes, it crashes 3ds Max entirely. Obviously that kind sucks if you left the render going on over night or something. It sucks to come back to your workstation to find out that it crashed on frame 2 lol.I know there are tools that can inform you of a crash when it happens, but meh.
Anyway I'm just curious about what some of your experiences with VRay GPU are in terms of animation.
I'll preface this by saying that I've been working with VRay next and now VRay 5. I'm hoping to have a general discussion with some of you who have been rendering animation with VRay GPU. I've been doing some arch viz with VRay for a few years so if my thinking and methods and understanding on this has holes feel free to point them out, I'm no expert. I approach using VRay with more of an artist brain than a technician, so it's kind of free form to find what works for a particular project. I've slowly learned more and more about what is technically needed to render a good animation, and here are a few things I've noticed about the different approaches. I'll share a few things I've learned about working with VRay GPU, which you might find helpful or if there are solutions and things I haven't thought of, please let me know.
With Light Cache, it is great for stills, but I can't seem to understand why it is recommended for animation. On the recommended settings, (now default for animation) of 3000 LC subdivisions and 8 retrace, It is extremely likely that some of your frames will have "unhandled exception errors." These errors will occur randomly, there is very little you can do to anticipate when these will happen, which I guess is just the nature of data going in and our of GPUs. 95% of my animation shots that I've attempted to render on light cache, have taken a super long time to finish because some frames simply won't render correctly in sequence. I've read in a few places that the way GPU's prepare the data for rendering is sometimes prone to error, and when something is not loaded in correctly it will produce these unhandled exceptions and crash the frame, and move on to the next frame where it may or may not happen again, depending on how the data loads into the GPU for that frame. When this does happen, I've noticed that it can be useful to run garbage collection, "gc()" in max script, and "freescenebitmaps()," to purge the bloat in your scene and load in your bitmap textures fresh. This usually fixes issues on those occasional problem frames. I'm rendering with Hybrid CUDA, cpu and gpus (Threadripper 2950x, 2X 2080TI). Maybe LC is more stable on strictly GPU? I'd love to know of what setups have worked for you with LC on what kinds of projects.
Knowing these pain points with Light Cache, I've been rendering more often with Brute Force for GI, and while it's noisier, it is WAY less prone to error. Sometimes some frames have a problem here and there, a few flickers that can be easily fixed, unhandled exceptions can still occur, however way less frequently, and re-rendering those frames almost always works like a charm. Flickers from LC are also so much more significant, sometimes the global illumination can vary WILDLY frame one frame to the next, that you usually cannot simply fix those issues in PS or AE or whatever. Flickers from LC almost always re-produce when you try to re-render these problem frames too, so you can't simply re-render them a lot of the time, which likely means you need to re-render the entire animation if you changes the render settings. In a LC animation I can have up to 25% of frames with errors. With Brute Force it is down to 5%. I've also noticed that generally on my rig, Brute Force achieves a lower noise threshold faster than LC, as LC takes a pre-render calculation done on CPU, which is factored into total render time. So I'm sort of wondering why is LC recommended for animation? Brute Force does have a few caveats though, in that when it crashes, it crashes 3ds Max entirely. Obviously that kind sucks if you left the render going on over night or something. It sucks to come back to your workstation to find out that it crashed on frame 2 lol.I know there are tools that can inform you of a crash when it happens, but meh.
Anyway I'm just curious about what some of your experiences with VRay GPU are in terms of animation.
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