Motion blur without movement

[Furnace]

Hi,
I'm creating a 360 of a car, the idea is sort of 'bullet time', so the car and wheels are static but I want the wheels to have motion blur to look like it's moving in a snapshot of time - anybody done anything like this before? From what I can see with Max and Vray motion blur the object has to be actually moving, it can't be faked.

Thanks in advance for any ideas.

[Syclone1]

I havent had my morning coffee yet so bear with me lol, would it work if you rotate the wheels 360 degrees for every frame so hopefully they would be rotating but appear to be stationary then hopefully adjust the motion blur to get the desired effect?

[Furnace]

Hi Syclone,
You don't need any coffee in the mornings - that worked perfectly, grab a beer. Many thanks.

[Rens]

Nice idea Syclone!

Another somewhat more complicated solution would be to set two keys and set the out of range type to cycle or loop.
For example if your frame range is from 0 to 100 set two keys on -2 and -1 (needs to be out of render range, otherwise the animation will pop at where the keys are set). Adjust the second key's value to how much you want your object to move.
Then adjust the motion blur settings, set duration to 0,5 for example (at least lower than 1) and interval center to 0,5. In this case if you render frame 10 VRay will look for motion between frames 10,25 and 10,75, which would be right in the middle of the animation slope you just made with the two keys. For the next frame the slope will look the same, meaning the motion blur and the position will be the same.
This will have the added advantage of being able to do translation as well, and also have different motion blurring for different objects.

[Joelaff]

I have always done this with the looped sub-frame key method like what Rens describes. You can also shift those keys back in time less than a frame to get the motion to occur around the frame itself so you can leave the interval center around 0, which works best for tracked footage and assures your keyframe poses are exactly as you have defined them. I know some animators of characters don't like to do this, while some do. (The argument is that, if your keyframes come to a complete stop (like with ease in and out), then you will have a frame that is unrealistically sharp... I prefer the adjust any keyframes to be correct, rather than mangle the camera position at every frame (for tracking purposes).