Strange problem with apparent brightness of HDRI vs the actual light appearing in scene

[Dade]

You need to enable architectural glass on window material or it will a scene extremely difficult to render for a path trace:

You should also disable "Out of core" rendering, I doubt it was intentionally enabled.

There are also hundreds of point light sources (i.e. the circle on the ceiling): it is a quite killer setup for rendering times.

[TStrolia]

You need to enable architectural glass on window material or it will a scene extremely difficult to render for a path trace:


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You should also disable "Out of core" rendering, I doubt it was intentionally enabled.

There are also hundreds of point light sources (i.e. the circle on the ceiling): it is a quite killer setup for rendering times.

I actually did enable out of core intentionally but mostly because I was getting some crashing in the full scene and that seemed to lighten up on the crashes. I don't understand it well enough to know why it's working so maybe you can help explain why that reduced my crashes but I will turn it off if it is a bad idea. And the hundreds of point lights are gone. They were ported from another model I had made in a different engine which runs pointlights with physical scale and has no effect there. I changed it to a mesh light. I started running architectural glass too. I don't love what it is doing to the realism of the inside of the doors but I am going to put bloom on it anyway so at that point I am sure architectural is going to be just fine.

Thanks again for taking a look and if you are able to help me better understand why to / not to use out of core rendering I would love to know, and if you have any idea why it was helping with render stability.

Also, while I have you, is there a huge difference in regards to caustics when using path gpu with light paths instead of CPU BiDir? I know originally you needed BiDir for caustics but I saw light paths and have been using that. I see a huge leap in render time being able to use my GPUS but BiDir seemed brighter over all, but BiDir didn't seem like it was making any serious changes to the caustics vs light paths so I am also kind of curious about if theere is a reason to or not to use light paths situationally besides the obvious which is, you do or don't have caustics. But are there any other benefits or repercussions to doing it one way or the other?

[Dade]

Thanks again for taking a look and if you are able to help me better understand why to / not to use out of core rendering I would love to know, and if you have any idea why it was helping with render stability.

Out of core rendering should be used when you run out of GPU ram, were you ? What GPU do you have ?

Also, while I have you, is there a huge difference in regards to caustics when using path gpu with light paths instead of CPU BiDir?

BiDir uses MIS (Multiple Importance Sampling) between eye and light paths while path+light tracing is static partition of the work (i.e. light tracing for caustics, path tracing for everything else). So, in theory, BiDir could have a bit less noise in some case however path+light tracing is so much faster that is pretty much always better.

[TStrolia]

Thanks again for taking a look and if you are able to help me better understand why to / not to use out of core rendering I would love to know, and if you have any idea why it was helping with render stability.

Out of core rendering should be used when you run out of GPU ram, were you ? What GPU do you have ?

Also, while I have you, is there a huge difference in regards to caustics when using path gpu with light paths instead of CPU BiDir?

BiDir uses MIS (Multiple Importance Sampling) between eye and light paths while path+light tracing is static partition of the work (i.e. light tracing for caustics, path tracing for everything else). So, in theory, BiDir could have a bit less noise in some case however path+light tracing is so much faster that is pretty much always better.

In a sense I was. For some reason I am crashing using 2 cards so I disabled my second card. So I have 11gb of graphics instead of 22 right now and the scene is a whole lot of 8k tiff textures and without it I was crashing before the render started. No sorta hang, blender would just close.

And thanks for the explanations. I am usually in an either or situation withthe engines. Either my engine is bidir OR it is path... I AM NOT USED TO ALL THESE OPTIONS lol. Yeah path+ light paths is significantly faster but I notice is way less consistent with noise cleanup. It will be crystal clear except for those 8 fireflys at 8000 samples meanwhile bidir will be completely clear at 3000 samples but it took twice as long to get to 3k as it did to get to 8k with path + light paths.

thanks again Dade

[B.Y.O.B.]

For some reason I am crashing using 2 cards so I disabled my second card. So I have 11gb of graphics instead of 22 right now

Usually, GPU RAM can't be added up when using multiple cards. Each card needs a separate copy of the scene, so the card with the least amount of RAM limits the available memory budget.

We currently don't support solutions that enable sharing of GPU RAM, like Nvidia NVlink for Quadro cards.

[TStrolia]

For some reason I am crashing using 2 cards so I disabled my second card. So I have 11gb of graphics instead of 22 right now

Usually, GPU RAM can't be added up when using multiple cards. Each card needs a separate copy of the scene, so the card with the least amount of RAM limits the available memory budget.

We currently don't support solutions that enable sharing of GPU RAM, like Nvidia NVlink for Quadro cards.

That makes sense. I was wondering about that. Because I am usually fine if I disable one card or the other but with both I crash. Doesn’t really matter which I leave enabled but with both I have a lot of problems with cacheing. If it’s true that the 3080ti will have 24gb of graphics ram I’ll grab one of those in a heartbeat. For the time being in my current project the average Image file size is around 120mb And I have around 80 images in total so that’s around 9gb of image textures in the scene.

I have been a maya user for the last 6 years and am just returning to blender so I don’t know if there is any good way yet to create scene versions but if there is I can dumb down some of those files to 2k or 4K from 8k. Right now I have a lot of render cams and just don’t want to go to each of the 250+ objects and adjust accordingly based on which camera I am looking through. If I can figure that out it will certainly free up some memory.