GI flickering with irradiance map preass (animated objects and camera)?

[jasonhuang1115]

Hi,

I have followed the official tutorial and combined it with suggestions found in this forum to apply the two-pass approach to render my scene that has animated objects and animated camera. But, I still get very obvious splotchy flickering all over the character in the Raw GI element??

The exterior scene has one animated character that will be composited with live-action plate, several Vray Rect lights with "Affect Diffuse" turned off surrounding the character, a Maya direct light to serve as the sun, a dome light with HDR map. When the scene is rendered with LC + LC, the Raw GI of a test frame looks pretty smooth. I assume that the irradiance map is the source of GI splotchy flickering. If I render a single frame with Interp. samples set to 40, the Raw GI looks smooth, but not when I use Interp. samples of 40 for the prepass and 20 for final render?

Here below is my render settings for prepass:


And for final render (resolution: 1280x720, Light Cache turned off because I render the prepass with "Use Light Cache for Glossy Rays" off)


Any comment or suggestion will be highly appreciated.

[vlado]

If I render a single frame with Interp. samples set to 40, the Raw GI looks smooth, but not when I use Interp. samples of 40 for the prepass and 20 for final render?

The interpolation samples are only used during the final rendering; it does not matter what they are during the prepass. Can you also post some images or send them to vraymaya@chaosgroup.com?

Best regards,
Vlado

[jasonhuang1115]

Reading from the official tutorial where the number of Interp. samples is lowered for final render, I therefore thought I should set the value higher to bake smoother irradiance map and then use a lower setting because samples of multiple frames will be blended.

Will the Mult Subdivs under the DMC Sampler affect the prepass quality? I set it to 0.01 for tuning final render quality with faster feedbacks. When I set this back to 1 for prepass render and final render, the Raw GI element of final render comes out much smoother. I then try Mult Subdivs of 1 for prepass and 0.01 for final render, the Raw GI element is still smooth. Can you confirm that the low Mult Subdivs setting during prepass causes the splotchy flickering in Raw GI element?

Thanks,
Jason

[Zdravko]

As Vlado mentioned the Interpolation samples are only used for the final rendering to interpolate the samples from different frames.
Also, if you change the Mult Subdivs value it will affect the pre-pass quality because it will affect the Subdivis value of the irradiance map.
If you calculate the irradiance with a low Subdivis value that may be the reason for the flickering.