Progressive renderer not clearing ? hdri light weirdness.

[anthonyh]

hi,
i`m getting a strange result with progressive vs bucket. (image on the left) is progressive after 3000 passes and NT set to 0.001, it`s clearly way too noisy and it seems some areas have much more noise than others, almost a box shape 2/3 of the image towards the lower rightof the left hand image. (image on the right) is bucket mode which looks nfine. it`s just a vraymtl with some glossy reflection.
ok, i`ve found it`s a vray dome light that`s causing it. it has a vrayhdri on it although it does the same whether the hdri is on or off. how come ?

thanks
anthonyh

[tashko.zashev]

Big difference in noise level for those renders indeed. Would it be possible to send us that scene to test it here?
In your post I can't find information about the V-Ray build. Please give me the exact Max and V-Ray versions used for this render.

[anthonyh]

hi,
oh sorry it`s vray 3.40.03 and 2016. i`ll try and send it over later.
thanks
anthonyh

[tashko.zashev]

Thank you.
You can send the scene to support@chaosgroup.com if it has any confidential data.

[anthonyh]

hi
i stripped it down and sent it. it produces the same results.
thanks
anthonyh

[tashko.zashev]

Thank you. I will post here when we have any news on this issue.

[tashko.zashev]

We found what is the issue here. The noise in Progressive rendering can't be cleared when in settings Subpixel mapping option is enabled and Camera exposure is either long or very short. The issue is now forwarded to our developers.
So until the fix came out you can switch Subpixel mapping Off or set the Color clamping to a higher value.

[anthonyh]

hi Tashko,
ok thanks. I`ll do that.
anthonyh

[anthonyh]

hi,
sorry to revive this but would the same subpixel issue also explain the lack of motion blur sampling in progressive as well ? it doesn`t seem to fix it like the previous above issue.
progressive 1/100 NT 0.002 MSR 24. subpixel/clamp off. around 1000 passes.

thanks
anthonyh

[tashko.zashev]

Probably this is a separate issue. Is it possible to send us that scene to our support mail ? Thank you in advance.

[anthonyh]

sure i`ll do it end of day.
thanks
anthonyh

[anthonyh]

i`ve sent a cut-down file through anyway, but i`ve found the cause. the `trace reflections` tick was off on the material. switch it on and it`s ok. not sure if that`s expected behaviour or not ?
motion blur does seem to take longer to clear than the rest of the scene, though that might be normal.
thanks
anthonyh

[anthonyh]

hi,
Also while i`m thinking about it i`m having issues with motion blur geometry samples. if i use 12 samples it works fine, push it up to 24 and also fine but if i push it up to 32 it all goes wrong, the lc/rendering takes exponentially longer and it all looks bizarre like rotor blades just disappearing.

And sorry one more thing, we`ve had weird issues with motion blur `teleporting` geometry (rendering across the screen where it isn`t in the viewport) and acting very weird, rendering copies of itself off-centre and offsetting across the screen. Now the cause is generally because of 1 of 2 things, scene scale or movement speed. If i move a helicopter across the scene a large distance, say a distance unreasonable for a helicopter to *actually* move(look it happens sometimes! )then the motion blur goes berzerk. I`m *only* using motion blur on the rotors, everything else is turned off in scene in vrayproperties(tick box off, samples to 1), I`m also not using camera motion blur. Is this expected behaviour ? I know vray prefers the scene to be more realistic in scale but sometimes it`s tricky because max generally doesn`t like small stuff in a large world (like viewport clipping with large and small objects) and sometimes we`re just building a nice looking scene not a simulation to exact atomic scale. Just curious if vray should cope or not ?
thanks
anthony

[tashko.zashev]

i`ve sent a cut-down file through anyway, but i`ve found the cause. the `trace reflections` tick was off on the material. switch it on and it`s ok. not sure if that`s expected behaviour or not ?
motion blur does seem to take longer to clear than the rest of the scene, though that might be normal.
thanks
anthonyh

This is somehow expected behavior since there is no color information (color value in RGB is 0) in big render areas around the fin. This is when `trace reflections` is off. When enabled, the Progressive image sampler can generate more adequate mask for the current render region.
If you prefer to keep this option disabled, then you can try to set higher minimum subdivisions for the Progressive sampler. According to my tests 3 or 4 are enough.

[tashko.zashev]

hi,
Also while i`m thinking about it i`m having issues with motion blur geometry samples. if i use 12 samples it works fine, push it up to 24 and also fine but if i push it up to 32 it all goes wrong, the lc/rendering takes exponentially longer and it all looks bizarre like rotor blades just disappearing.

And sorry one more thing, we`ve had weird issues with motion blur `teleporting` geometry (rendering across the screen where it isn`t in the viewport) and acting very weird, rendering copies of itself off-centre and offsetting across the screen. Now the cause is generally because of 1 of 2 things, scene scale or movement speed. If i move a helicopter across the scene a large distance, say a distance unreasonable for a helicopter to *actually* move(look it happens sometimes! )then the motion blur goes berzerk. I`m *only* using motion blur on the rotors, everything else is turned off in scene in vrayproperties(tick box off, samples to 1), I`m also not using camera motion blur. Is this expected behaviour ? I know vray prefers the scene to be more realistic in scale but sometimes it`s tricky because max generally doesn`t like small stuff in a large world (like viewport clipping with large and small objects) and sometimes we`re just building a nice looking scene not a simulation to exact atomic scale. Just curious if vray should cope or not ?
thanks
anthony

Please send us some test scene files for these issues to our support mail again. It would be hard to investigate without scene files or screenshots.