DoF defocus when motionblur is enabled

[LudvikKoutny]

Hi,

i have a problem that already happened independently on a second project, which is extremely frustrating.

We usually get a scene with standard max cameras which we then convert to Vray Physical Cams... Almost always, cameras have target placed incorrectly, so i have to manually keyframe specified focus distance to get object of interest into the focus.

Now, the problem is that whenever i use both depth of field and motion blur, camera get's significantly out of focus at some point of animation. Strange thing is that it does not happen when i render single frame on my workstation. It happens only when i send the animation to render on a farm. So output rendered on my workstation has correct focus point, but output of an identical scene rendered on a farm is defocused.

Also, as soon as i disable motion blur, camera focuses properly... even on output rendered on our farm.

I am totally puzzled, as i tried everything including re-creating cameras from scratch and carefully copying every single keyframe from old camera to the new one.

EDIT: All machines on the farm have matching Vray version installed.

[instinct]

Is it really DOF or very heavy MoBlur? In the latter case, check if there maybe is "invisible" animation (gimbal jumps, euler issues, subframe keys).

Regards,
Thorsten

[LudvikKoutny]

No, i am quite confident it is DoF. I am comparing same frame from my workstation to the frame that came from the farm, amount of MB is very subtle in the shot, but on the one from renderfarm, all of the background is totally blurry from defocus.

[3LP]

Hey

I had the exact same problem last week, I had to disable the MB for my final render

http://www.chaosgroup.com/forums/vbu...when-using-dof

I'm currently creating a simple scene fresh from scratch to send a scene and report the problem...

[LudvikKoutny]

Yes, i just noticed... not only that it causes DoF defocus, but it also causes random strong FoV changes when rendering on farm via backburner. When rendering on a single machine, these problems do not occur. When i disable motion blur, everything works 100% correctly even on network rendering, but as soon as i enable MB, i get random defocuses and FoV changes throughout the entire animation.

All machines on the farm have matching 3ds Max Product Update and Vray version.

[instinct]

Do they also have matching language versions and settings?

[LudvikKoutny]

Yes, they have. I even thought it could be a decimal separator problem, so i changed it to the same on all machines, but still no luck... Only disabling motion blur works, but motion blur is really necessary in most of the projects.

[instinct]

Did you check for euler and sub-frame issues? That would explain why it renders fine without moblur and only moblur leads to the subframe abnomalies to show. In this case it should be reproducible. As in the "errors" are always the same for a specific frame.

Regards,
Thorsten

[gimiky]

we've been seeing what sounds like the same problem lately when the camera is "zoom" blurring and the motion blur shutter angle and offset in the camera are "unevenly" paired. for example, when using a shutter angle (movie cam) of 135 and an offset of -90, this effectively puts the blur center at -0.125, and it appears that this is adding in some bad subframe info.

the strange thing is that if a single machine renders the sequence the problem does not show up--the frames must be rendered individually to see the jump. locally you can demonstrate the discrepancy by comparing a frame rendered on its own with the same frame rendered in a sequence.

[3LP]

Yeah I checked that myself, that's not the issue

I could reproduce the bug with a fresh new scene, teapots and a fresh new cam.

I've uploaded the scene here : https://dl.dropbox.com/u/368267/VrayCam_Dof_Bug.max
and rendered out on the farm to see the problem here : https://dl.dropbox.com/u/368267/VrayCam_Dof_Bug.mov

Hope this help,

Stan

[3LP]

Hey there,

any news about this?
We might need it in other upcoming projects and I was wondering if it's a small fix that will be updated in the new SP or after?
Or am I doing something wrong and it's a user error

Thanks

Stan

[tashko.zashev]

Hi Stan,

This should be already fixed in the nightly builds.

[3LP]

Great news, thanks a lot!

[UbiGuy]

Someone can confirme it have been solve in the last build????

We got the same error here....

Thank you!

[vlado]

Can you get us a scene to vray@chaosgroup.com ?

Best regards,
Vlado