Hi,
I’d like to use the motion blur bias parameter in a scene with a Max Physical Camera, and I’m unsure how to get it to work.
The parameter in the render settings works with a standard target camera, but doesn’t seem to work with the physical cam, and I can’t see the option anywhere else.
Does Bias work with the PhysCam, and if so, where do I set it?
Cheers,
John
In a recent project I used the shutter efficiency parameter in the Camera Settings in the V-Ray render dialog. This works together with Physical Cameras, as long as you tick the motion blur checkbox in both locations. I used a shutter efficiency of 0.1, which made the motion blur effect more pleasing. However, this sort of shrinks the blur, so you have to alter the duration in the PhysCam to compensate.
Using the blur bias this way should work as well.
Thanks Oliver.
Just tried that, and it does give a nicer motion blur effect than the standard, but I can’t get the rear curtain flash effect I was looking for, which I think a high Bias setting would.
But unfortunately with the PhysCam, that setting doesn’t seem to do anything.
I’ll definitely be using the shutter efficiency settings in the future though, so I appreciate the tip.
Cheers,
John
What do you mean by rear curtain flash? What is the effect you are aiming for?
By the way, I just tried it. You are right, the bias setting doesn’t have any effect 
It’s basically a long exposure with a flash at the end, so you get the subject in sharp focus at the end of a motion blur.
Like this…
Cheers,
John
Ah, I see. I don’t have any ideas, besides rendering twice and then putting the images on too of each other. One with blur, one without. Might that be an option?
Yeah, that’s what I’ve done in the past. Just wondering if there’s a way of doing it in one, and perhaps having a bit more falloff to the effect.
Cheers,
John
When I look at a road with a fixed gaze and relax, I can sometimes see a blurred trail behind passing vehicles. I think this is more or less people’s perception of motion blur and it just looks good in photos. (Like in the example with the red car above).
Is there not a way to get this rendered the same way?
It works with the standard camera. I think I may have gotten it to work with the VRay camera, but usually if I want to do special motion blur tricks I use an old school standard camera. You can do rear curtain sync type effects or crazy long blurs. The bias can and should exceed -1.0 to 1.0
We never touch the Max physical cam. Typically
it’s VRay cam or standard for these blur tricks.
You can do rear curtain sync type effects
How this can be done?
I am using V-Ray for Rhino and we have access to motion blur since the last update, but not all parameters. I am trying to understand what is needed.
Great effect. Which parameter makes that the car is clear visible and the motion blur is behind?
I should add that you need to up the geometry samples from the default to in this example 75, which puts the car in focus but creates the effect, for some reason which I admit I have no idea about 
Maybe it’s realistic but I don’t know the facts of it.
Would like to try this with a car derived from Catia data, but I doubt it can be rendered because of exceeding RAM limits…
Just deal with the exterior for the highlights maybe, ignoring the interior and comp that in.
Hmm…I remembered this thread where we were trying effectively the same thing https://forums.chaos.com/forum/v-ray…-infront/page4
So I just tried with the setup I used for this post and it works fine now, so maybe they changed something or we just didn’t happen on the right settings earlier.
Scratch that, it doesn’t.
Actually on further testing this doesn’t work other than for a single frame. In all frames the blur length changes but the car remains stationary.
I had a feeling that it was too simple to be true
