In-render Corona Motion Blur vs Velocity Pass (Roads)

[swedgedesign]

Hey guys

Been working on a still for a client where a car is turning a corner and the camera tracks the car, keeping the same motion to keep the car in focus. That all works great, and the wheels blur nicely, and so does most of the background except for the road.

Here's a comparison between in-render MB and using a Velocity Pass to add it in post.

Now the MB in post looks correct, but why is the in-render so different and is there something I'm missing? (I've cranked up the samples to the max but it loses all the detail and doesn't give that nice curved look)

Right now I'm having to run 2 passes, one with MB and the other with Velocity pass so I can blend the best of both in post but an in-render solution would be fantastic.


Cheers

[swedgedesign]

Had some help on this, and apparently there's a similar issue in Vray when using the IPR.

In my previous post, I had the camera and car connected to the same dummy which was following a path to create the motion. I unlinked the camera from the dummy, and manually keyed in the animation, and then it worked.

As I'm typing this, I'm thinking maybe it has something to do with the path constraint being a linear float controller by default, instead of a bezier float as the XYZ is.

EDIT - attached the manually keyframed render