Vray velocity pass and RSMB vector plugin inside aftereffects.

[stevesideas]

I've recently re-started using the vray velocity pass to be used inside aftereffects and RSMB. My process is to normally render one frame at the estimated fastest moving point during the animation and had a look at the readout on the vray velocity pass showing the value for that frame. I then add 10 to this figure and enter this into the max displace. I render out to 32bit EXR. Clamping is off.

Problem is, when I bring this file into aftereffects and use the RSMB plugin the motion blur doesn't seem correct. It always seems to be blurring the image no matter if there should be motion blur or not.

What am I doing wrong ?

[Morbid Angel]

If you are rendering out a totally separate vector pass, then its against a grey bg, so in AE before you use it, you must remove the grey bg, or rather export just the Red and Green channels. I think the easiest way for you to find out if its working correctlyt is to move an object on one axis Y and another object on another axis X, and export that frame to ae and see what you need to do to get it looking correct.

[stevesideas]

I'm actually rendering out a vector pass for everything in the scene at the same time. So nothing is separated. Can it still work like this if the entire screen is full of moving objects. ie, a cyclist moving down a road with people walking by and traffic, or would I have to render separate passes for everything to get the right effect ?

[Morbid Angel]

I'm actually rendering out a vector pass for everything in the scene at the same time. So nothing is separated. Can it still work like this if the entire screen is full of moving objects. ie, a cyclist moving down a road with people walking by and traffic, or would I have to render separate passes for everything to get the right effect ?

Well its two different things we are discussing here. To get the motion vector working, you need to clip off the grey (this should get it looking right). To get the motion blur to work with multiple layers is a kind of a business where you have to comp and see. Usually you can get away with a lot, but if you have some fine detail, like fine lines intersecting, this could cause issues. Typically you would have to separate it in some layers, like fg, mg, bg as example.

[stevesideas]

ok. So it sounds like I just need to remove the grey and it should work with my scene. When you say just export the red and green channels are you talking about directly from max in the VFB rollout ?

[Morbid Angel]

No, I mean in AE. We comp in nuke over here, so we would just clip off the grey at 0.5 and then get pure red and green values, and plug those in to the vector node.

What I mean is, there is another way to achieve what Im talking about without doing any changes to the vector pass, if you save out a multichannel exr, then the velocity is plug and play, no need to change anything.

Lastly, you don't need to measure the max velocity interval, if you save out unclamped vector, the values should be 1 to 1 from the velocity to the vector blur node in AE.

[stevesideas]

That's very useful information. Thanks a lot. Looking forward to trying out this new method

[stevesideas]

Ok. I'm still having problems here. I've tried using shift channel and turning off the blue channel as described here: http://www.timsportfolio.co.uk/tutor...-pass-3ds-max/

But I just end up with a very yellow image.

Here is a link to one beauty and velocity pass EXR. Maybe someone could take a look and see if they have more luck getting this to work.

Just to note that the two bolts in the middle of the screen are only moving very slowly, the other parts are moving much quicker.

[stevesideas]

Ignore previous post. I've just got this working !!!! What a relief. In aftereffecrs colour management for the clip I had to turn on "preserve colour management".