Random buckets do not render

[Vipera]

I am having a problem with random buckets skipped during render for this specific shot. I have a rocket flying in foreground with Earth in background. The problem happens in rocket flame area. The flame object is animated mesh with procedural material. Every time I render I have skipped buckets around same area. Some of the frames render fine, without skipped buckets. I have no clue what is causing skipped buckets and what I have to tweak to solve this. I need some advice, please.

[Vipera]

After multiple attempts I was able to fix this issue by adjusting falloff curve in lower point, slightly rising it.

[hermit.crab]

Mind if you simplify the scene and send it so we can troubleshoot?

[Vipera]

Mind if you simplify the scene and send it so we can troubleshoot?

I have sent file to tech support, I had attached .max file with two missile exhaust materials. The material with 'Bad' word is what was causing the problem. The material with 'Good' word is fixed material. The problem happens when opacity map is too dark. It prevents buckets to render in that area.

[hermit.crab]

This happens when camera rays hit a transparent pixel and assume the whole bucket is transparent. To avoid this, the minimum Bucket subdivisions should be increased (a value of 2 fixes the issue).

[Vipera]

This happens when camera rays hit a transparent pixel and assume the whole bucket is transparent. To avoid this, the minimum Bucket subdivisions should be increased (a value of 2 fixes the issue).

This is good to know! Thank you for clarification.