Vray GPU - Camera motion blur (ISSUE)

[jimmy_hagenaar]

Dear Chaosgroup,

I have an issue with rendering a scene.
I have a camera that is parented to a car, whenever I render it with CPU, the motion blur is affecting only the enviroment (As it should).
Whenever I switch render to GPU, the enviroment becomes crystal clear and instead car is getting heavily blured. Seems like in Vray GPU mode, drops the camera out of the parent group and breaks any constraint links to moving objects.
Parent constraint doesn't work either.
See the attachments:

I use Maya 2020 and the latest Vray 5 hotfix 2.

I hope you can help me with resolving this issue.

Kind regards,
Olie

[hermit.crab]

How is this environment set? Are these trees objects or a texture projection? Best send the scene via the contact form so we can take a look. Address it to me in the subject and mention this forum thread in the message.

[tom_hh]

Hey I have nearly the same issue here. I tried to render an ocean sim with phoenix fd and particle shader. Motionblur is set. With cpu the render is slow but fine, with gpu the motionblur is gone. Same config as yours. maya 2020 vray5 hotfix 2, latest phoenix.

Regards Tom

[hermit.crab]

tom_hh Could you send the scene as described above, since no scene was sent from jimmy yet?

[tom_hh]

Hey Alexandar, thx for the quick answer.
I can send you a scene, but its huge. There are phoenix ocean sim files 2.5 gb each frame. I guess 2 frames are enough to see the issue. Plz send my a google drive link for the upload. I already contact the support form. Maybe we use this way for the link.

THX! Regards tom

[fixeighted]

Particle shader motion blur isn't supported on gpu https://forums.chaosgroup.com/forum/...pu#post1093262

[jimmy_hagenaar]

Good day,
@aleksandar.hadzhiev Sorry for late reply, I had to leave to the funeral, so I was unable to reply for the past weeks.
I will share the scene with you tomorrow.

Kind regards,
Olie

[jimmy_hagenaar]

Good day,

I have submitted the ticket to Chaosgroup, together with the scene.
You can find the scene in attachments here.

Kind regards,
Olie

[hermit.crab]

Thank you for the provided scene. There is no bug here, but a simple UI confusion. The "Camera motion blur" seems to be deactivated in the GPU render, but the option itself is located under the "Motion blur" checkbox (Render Settings>Overrides), which when disabled is hidden, though still active. Enable the camera motion blur and the issue should disappear (activate Motion blur>check Camera motion blur>Deactivate motion blur). I'll inform our devs about the matter so we can find a solution to the UI confusion.

EDIT: I've logged an improvement request to relocate the option (internal bug-tracker id: VMAYA-10190).

[jimmy_hagenaar]

Thank you for the provided scene. There is no bug here, but a simple UI confusion. The "Camera motion blur" seems to be deactivated in the GPU render, but the option itself is located under the "Motion blur" checkbox (Render Settings>Overrides), which when disabled is hidden, though still active. Enable the camera motion blur and the issue should disappear (activate Motion blur>check Camera motion blur>Deactivate motion blur). I'll inform our devs about the matter so we can find a solution to the UI confusion.

EDIT: I've logged an improvement request to relocate the option (internal bug-tracker id: VMAYA-10190).

Thank you for your reply Aleksandar.
To be honest I still haven't found the option in the render settings>overrides.
The motion blur is active in my physical camera and if you compare both images, then you will notice that both of them have motion blur. Gpu render flips the motion blur so to say, the moving car gets blurred instead of background, while on cpu the background is getting blured, as it is meant to be.
I'm not sure if it's an option thing.

Kind regards,
Olie

[hermit.crab]

This is the option I'm referring to (see screencap). It affects the Physical camera motion blur as well, however, it's "hidden" when the global motion blur is disabled. So simply, enable the global motion blur checkbox > enable the Camera motion blur > disable the Motion blur.

[jimmy_hagenaar]

This is the option I'm referring to (see screencap). It affects the Physical camera motion blur as well, however, it's "hidden" when the global motion blur is disabled. So simply, enable the global motion blur checkbox > enable the Camera motion blur > disable the Motion blur.

Wow, thank you. Looks like I have been exhausted and overlooked the option.
I enabled it and the image looks now as expected!

P.S. One last thing. Can you please help me with figuring out, why lighting between GPU and CPU is quite off, I understand that engines are different.
However, I have tried to increase the intensity of lights in GPU scene, the result remains the same. Have I missed any setting?

Thank you Aleksandar!
I wish you a pleasant day

Kind regards,
Olie

[hermit.crab]

The difference stems from one of your lights (Light_Sun_01_Main), which has its "No Decay" option activated, which is not supported on the GPU (and has been removed from the UI, since the option is deprecated).

EDIT: This turned out to be a UI bug, the option shouldn't be visible in either CPU or GPU. It has been logged (internal bug-tracker id: VMAYA-10205) for developer investigation.

[jimmy_hagenaar]

The difference stems from one of your lights (Light_Sun_01_Main), which has its "No Decay" option activated, which is not supported on the GPU (and has been removed from the UI, since the option is deprecated).

EDIT: This turned out to be a UI bug, the option shouldn't be visible in either CPU or GPU. It has been logged (internal bug-tracker id: VMAYA-10205) for developer investigation.

Thank you Aleksandar, for your assistance!

I have replaced the sphere light with the sun and got it very close to the original.
However, I've noticed that reflections intensity of the Domelight "HDR" are still quite different between CPU and GPU.
On GPU the intensity of reflections is just off by a lot.

I have created the brand new domelight with the default setting and pluggen in the hdr texture. Result comes out the same.
Any idea on why it is?

Thank you!

[hermit.crab]

I am not certain if I'm testing correctly on your previously provided scene. Could you attach (or send it via the contact form addressed to me in the subject, with a link to this thread in the message) a simplified version of your current one?