Velocity pass differences

V-Ray V-Ray for 3ds Max General
1

Hi, Ive rendered a velocity pass saved within a EXR but the results are different to what is seen on the VFB,

velocity_test_F420.jpg
velocity_test_F420.jpg1920×1080 37.1 KB

This is what I get direct from the VFB which produces the correct motion blur in RSMB,

velocity_test_from_EXR_F420.jpg
velocity_test_from_EXR_F420.jpg1920×1080 73.6 KB

This is what I get from the saved EXR raw file which creates very strange motion blur!

Anyone know where I’ve gone wrong on this and how to correct it without re-rendering?

Thanks,
Justin

velocity_test_F420.jpg
velocity_test_F420.jpg1920×1080 37.1 KB

velocity_test_F420.jpg
velocity_test_F420.jpg1920×1080 37.1 KB

velocity_test_from_EXR_F420.jpg
velocity_test_from_EXR_F420.jpg1920×1080 73.6 KB

2

it could be 1 gamma correction (thought I don’t think so) it could be 2 blue channel is not visible. What program are you using to do the rsmb in? You basically need to specify only red and green channels to it, if they are contaminated with either option 1 or 2, they will be wrong.

3

Hi dmitry, I’m using After Effects to apply rsmb, I have tried messing around with the gamma to no effect.
The EXR,s where rendered via a farm so I’m wondering if there is an error there, I will try rendering a multi channel EXR locally to see if the results match,

cheers,
Justin

4

I don’t use after effects, but if I recall correctly you need to tell it to not apply gamma correction to 32 bit image. I think it might be the problem.

5

I have rendered the same frame locally and I get the same result, so not a farm error. If I save as .vrimg the velocity is as expected, but this is viewed in VBF.
I’m not sure how you tell after effects not to apply gamma so could be this, but it hasn’t applied gamma to the RGB or any other passes.
What program would you recommend to use instead?

6

In the EXtractoR you need to set the black point to -1.

7

that worked! cheers Geoff.
thanks for the help guys,