What is diffrent VrayVelocity and lm2DV(or Maya mentalray renderpass normalize 2dMV)?

[nihonjung]

Hi
Our company work Max with maya.
We have problem of RSM velocity images because different information MV 3dsMax and Maya.
I converted Maya scene to 3dsMax and render velocity on 2 soft.
and result is not same. I want two velocity information same or similarly.
I try change Max velocity and get similar MV value but another cut I do this work again.

What is the algorithm of vrayVelocity?
and If I setup Maya normalize value 512 how much value I do setup max velocity on 3dsMax for all cuts?

regards

[nihonjung]

Hi, again.
I have another question about VrayVecocity element.
velocity color image rendered with Max cam diffrent with velocity color image rendered with Vray Cam.
and VrayVelocity which rendered with vray camera result not change when I changed shutter angle and shutter offset or change motion blur on/off or duration,interval center.
Is that affect by camera property(like shutter angle, shutter offset or something like Maya motion blur attribute Shutter open/close?
and What is VrayVelocity means?

regards

[vlado]

If you keep the Max. velocity attribute of the Velocity render element to 1.0, then: when motion blur is disabled, the velocity element represents the number of pixels a point moves for one frame. When motion blur is enabled, the motion blur duration is taken into account (camera shutter speed when using physical camera, and motion blur duration otherwise).

If you change the max. velocity then the velocity is scaled accordingly. Note that by default the velocity is clamped between -1 and 1, turn off the "Clamp velocity" option to see the real values.

Best regards,
Vlado

[vlado]

Here is a very short tutorial for RSMB Vectors in Nuke.

(*) Open the attached scene: rsmb.zip, go to frame 5 and render.
(*) Open the Render Settings, go to the Render elements tab and click on the Velocity element to show its properties.
(*) Note the "Max. velocity in last frame" value - it should be something like 117.89. However, we will set the "Max. Velocity" value just above a little higher - to 130.
(*) Note that the output image format is set to PNG with 16 bits per pixel.
(*) Render the image
(*) You should get two files - rsmb_tmp.png and rsmb_tmp.velocity.png. Check that they look like in the attachment.
(*) Open Nuke, create Read nodes for the two images; for the rsmb_tmp.velocity.png image, make sure you set the "colorspace" to "linear" and not the default "sRGB". If you don't do that, you will get wrong result.
(*) Create the RSMB Vectors node; attach the velocity image as the "Motion vectors" input and the RGB image as the "Source" image.
(*) Set the "Max Displacement" value of the RSMB Vectors node to the same value we had in the "Max. Velocity" attribute for the Velocity render element in Maya - in this case 130.
(*) That's it. Render the result to produce the motion blur. As you can see the RSMB result (rsmb_nuke.png) matches the 3d motion blur result (rsmb_mb.png) quite closely.

Nuke result with RSMB Vectors (image doesn't have alpha here, hence the black background):


V-Ray rendered result with 3D motion blur:


Original RGB rendering from V-Ray without motion blur:


Velocity image for the above rendering:



Best regards,
Vlado

[nihonjung]

Thanks Vlado.
This helpful to me.

[nihonjung]

Thanks Vlado.