Adding motion blur to a tracked scene...

[evanerichards]

So, I have a scene which has been tracked. The track is really tight. I have some objects I'd like to add to the scene, but here is the problem. When I turn on motion blur and render it renders in between frames. Instead of rendering out from 3 it will render out frame 3.24 or something like that. And obviously when you slide the animation forward 1/2 a second it doesn't match up with the track anymore.

Is there any way around this? Any fix or clever ideas?
Please advise.

Thanks!

[t.petrov]

What are your motion blur settings?

Duration, Interval center, geometry samples.

[evanerichards]

Hmmm. I didn't know there were different ways to calculate it. The only way I know is to turn it on in the physical camera settings and it just calculates based on your shutter speed.

What should be the proper way of calculating motion blur if you have a tracked scene and need the geometry location to match the track for the duration of the shot?

[Neilg]

If you use a standard camera, the motion blur settings in vry->camera tabs of your main render settings are much easier to use. You pick the duration, center & bias in frames.

The physical camera has these too, but they're in degrees and fractions of seconds. And you have to change it to 'movie cam' to get access to them.

[Adbk]

Sounds like your interval center under your motion blur settings is set to .5

Set it to 0 and give it a try

[Svetlozar Draganov]

Would it be possible to attach stripped down version of the scene which contains the same issue ?

[super gnu]

i have the same problem here, in Max, tracked scene too. ive got camera motion blur disabled, i just have it for a waterfall in the scene to smooth it out. with an interval of 0.5 i get an annoying offset to the frame being rendered.. i tried an interval of 0 and it was worse.. interval of 1 seems to be just as bad.. any suggestions besides dropping the moblur?

edit: i had a duration of 4 frames, to get a nice heavy blur on my waterfall (its just a crude mparticle jobby) when i dropped to 2 frames with an interval of 1, it seems to be ok.

does this mean if i could set the interval to 2 (which i cant) id be able to use a duration of 4?

[joconnell]

You're totally right. If you use the default motion blur settings in the vray render dialog, vray will use the position of your objects as they move from one frame to the next so if you're rendering frame 0, it'll render the movement from frame 0 to frame 1 and it'll look more or less like frame 0.5 since your blur is centered in the middle. As the folks above have mentioned, you need to set your interval centre to 0 for it to lok to a tracked scene. Also bear in mind that if your track only starts at frame 0, then there's no movement before that point, and vray needs a place that an object is coming from and going to so it can calculate the motion blur. If you get your camera track and use the curve out of range types in the curve editor so that there's movement before and after the keyframes of the track it'll behave.