Progressive render updates only after multiple passes

[viscorbel]

Using 3.5 sometimes on heavier/messier scenes the progressive renderer sort of stops updating in vfb. The progress bar moves forward, passes increase but the image displayed is the same. Then after a couple of dozen passes it suddenly updates, and so on.The worst thing about this is that when you stop the render while it's "stuck" on earlier state, that lower pass/noisier image is what is left in vfb, even if the passes have increased significantly.

[Art48]

Maybe a dumb question but is it maybe calculating the denoiser while in that "stuck" time?

[viscorbel]

Nope, denoiser is off in that scene, and it sometimes gets stuck in the middle of the first pass (half the frame is still black/LC)

[yavor.rubenov]

Hello,

If it is not the denoiser, then maybe you have active Lens Effects?

Best regards,
Yavor

[samuel_bubat]

I have a similar problem that might be connected to this issue. Since 3.5. with heavier scenes when using "track mouse while rendering" it sometimes stops an the frame buffer partialy freezes. I can still see the buckets render but tracking or zooming doesn?t work. After maybe half a minute everythings back to normal. This can happen several times during a rendering.

[Art48]

I have a similar problem that might be connected to this issue. Since 3.5. with heavier scenes when using "track mouse while rendering" it sometimes stops an the frame buffer partialy freezes. I can still see the buckets render but tracking or zooming doesn?t work. After maybe half a minute everythings back to normal. This can happen several times during a rendering.

Did you try Alt-Tab and Alt-Tab again? Sometimes the VFB seems to lose focus even if clicked on and this only is fixed by alt-tabbing twice.

[viscorbel]

Hello,

If it is not the denoiser, then maybe you have active Lens Effects?

Best regards,
Yavor

yes, looks like that's the case!
I guess this means we should only enable lens effects after the render is finished? Otherwise, if the lens effects take a long time to calculate on larger resolution render, every pass after the calculation starts is lost.

[yavor.rubenov]

No you don't need to disable the lens effects.
What you are actually seeing is the lens effects result - a special channel added to the frame buffer called "effectsResult". No passes are lost - they are written to the RGB channel and from time to time the lens effects are recalculated from the data in the RGB channel and stored in the effectsResult.

If you are looking only in the effectsResult channel it would seem as if the rendering is updated after multiple passes but actually it is the lens effects updates.

How often this update happens is controlled by the Post effects rate in the System settings (https://docs.chaosgroup.com/display/VRAY3MAX/System)

You can set 0 there and the lens effects will update only at render end.

[viscorbel]

ok, that makes sense!