Vector Motion Blur With Vrayvelocity
Posted 23 February 2013 - 10:32 AM
just some test again, after waste many hour on the web to find how is it possible de composite Velocity Vray pass... As you know vray make you a strange vector.
normaly i cheked velocity on my .exr file and its works fine. So with the extra .exr i've put the vray velocity channel too and no result append with the vectorMotionblur tool.
But with the plugin RSMB vector work fine... really do not understand.
here a screenshoot, with a .tga file(Vray velocity) in 32bits and Channel boolean to convert R to vX and G to vY and a VectorMotionblur.
The second is a simple .exr file autogenerate velocity.
Posted 23 February 2013 - 02:02 PM
i think the vray velocity has its zero motion point 0.5 and backward motion beneath and forward motion up to one. so its normalized between 0 and 1. thats also the format that rsmb expects
so you have substract a value of 0.5 and multiply by the factor you defined as max motion in 3d
Posted 24 February 2013 - 08:00 AM
i've tested with 0.5 value to the VrayVelocity render, and the result is the same.
I think to explain the best i can, i attach these two's screenshoot.
First with the .exr file (backvectors), works fine:
The second with the VrayVelocity buffer on .exr file won't work even if i Flip the X or Y ...
Thank in advance
Posted 24 February 2013 - 11:18 AM
For data like motion vectors you should better use 32 bits per channel.
You can get some more details about different motion vector storage formats here: http://vfxpedia.com/...n_Vector_Passes
Try to play with the scale parameter. Sometimes you only achieve any visible effect when it's set to some hundreds.
Posted 24 February 2013 - 02:59 PM
Posted 24 February 2013 - 06:38 PM
Posted 25 February 2013 - 11:51 AM
@Gringo: I've try too xtract velocity from my exr, and to force Brightness to -0.5 and i have the similar pass.
Why Eyeon fusion vectorMotionblur is so different ? is an headache.
Posted 25 February 2013 - 02:56 PM
0 is no motion, +1.0 is one pixel foward/right/up and -1.0 is one pixel left/back/whatever :-)
The motion vectors your 3D app generates are a workaround that comes from a time, when there was no proper storage and rendering for floating point numbers, so it was done in an image from 0 to 255 with 127 (or 0.5) being the normal point. ReelSmart's motion blur plugin comes from a similar time.
You can see what numbers are inside a vector pass by switching on the color inspector subview (SubV button below viewers).
Posted 25 February 2013 - 04:25 PM
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