motionblur not working correct

[pixellusion]

hello chaos forum,

we're trying to implement vray7 in our c4d pipeline (once again ) (vray 7.00.02 and c4d 2025)

motionblur will not render properly. looks like interval center is always set to 1.0 regardless of what you set in the rendersettings.
(we need it to be on 0.5 to match our live action plate's motionblur)

any idea?

thanks and best regards,
basti

also there's a little bug when rendering with the vray frame buffer. it will assume 30fps when c4d rendersettings are set to 'from project' (eg. 24)

[viktor_angelov]

Hi pixellusion Thank you for reaching out to us!

Please share a screen recording of your workflow and results so we can observe the issue you are describing.
If you are able to do so in a simple scene, isolating the situation, that would be best.

[deyan.hadzhiev]

Hi pixellusion, can you share a bit more details about your setup, or even sharing a simple scene showcasing the problem would be best.

We changed a bit how motion blur works when V-Ray Physical Camera is used as the active camera (to align V-Ray for Cinema 4D with how other V-Ray integrations work). Basically, if you are using a Physical Camera, only the Geometry Samples from the Render Settings are considered. You can modify the Motion blur interval center using the Physical Camera's settings (depending on the exact type of the Physical Camera):



Basically you can change the Shutter Offset only for Movie Camera types with the dedicated parameter in the camera. Having the Shutter Offset to 0 will always set the interval center at 0.5 of the duration.

also there's a little bug when rendering with the vray frame buffer. it will assume 30fps when c4d rendersettings are set to 'from project' (eg. 24)

Yes, we are aware of this problem (thanks for reporting it nonetheless). The option was recently added to the newest Cinema 4D release (2025.2 - it was not present in 2025.1) and we have not yet added logic to handle it properly.

[pixellusion]

hello viktor and deyan, thanks for your help.

sure, here's my testscene and a screenshot showing the problem:


yes, a workaround is the movie camera with offset -90 degrees (180° shutter) this will give us the correct centered motionblur.
but in vray for 3dsmax etc it's usually the interval center 0.5 to get matching motionblur.
in c4d changing it to -1 or 1 will not change the motionblur at all.

thanks again,
basti

[deyan.hadzhiev]

Hi pixellusion, I'm glad you will be able to achieve your desired result.

but in vray for 3dsmax etc it's usually the interval center 0.5 to get matching motionblur.
in c4d changing it to -1 or 1 will not change the motionblur at all.

The Interval center is considered only when the camera is not a V-Ray Physical Camera. This is true for both V-Ray for 3dsMax and V-Ray for Maya. Same as in V-Ray for Cinema 4D - interval center is considered, only when you don't have a V-Ray Physical Camera tag on the active camera. Here is a screenshot from V-Ray for 3dsMax (with V-Ray Physical Camera):


Unfortunately, before V-Ray 7.00.00, the V-Ray for Cinema 4D integration did not behave like the rest and always considered the Interval Center in the Render Settings. While this is convenient in some usecases (like yours), it was causing many problems in setups where the Camera in the scene is also moving and has to match an object's motion in the scene - in such cases the motion blur duration has to precisely match the Camera exposure duration, so that is why it was always working like this in V-Ray for 3dsMax and V-Ray for Maya.

And about the negative offset - if you want the motion blur centered (i.e. the blur to start half-way before the actual current frame time), you are correct that you need to use -90 as offset when the shutter angle is 180 (at least if there is no Rolling Shutter - with it the calculation is more complex). If you need more details about this I can provide a full description of how this is calculated underneath.

[pixellusion]

hi deyan,

good to know, thanks for your detailed explanations

off to new tests!

best regards,
basti