View Full Version : Does anyone know how to connect my 2D motion vector from maya in nuke?

01 January 2012, 04:59 PM
Does anyone know how to connect my 2D motion vector from maya in nuke?, I understand thar I can connect it with Kronos and with MotionBlur, but... I'm doing something wrong because it doesn't work for me. If anyone knows... regards and thanks! (I first tried with Nuke VectorBlur, same result)

01 January 2012, 03:11 AM
Are your motion vectors rendered in a separate image from the color?
1. shuffle copy or copy node the vectors into the "motion" or backward/forward channels. This will depend the shader your using to create the motion vectors. Some separate out the +/- values into separate maps, which is why there is forward/backward. Other apps just do both in one, which is why you put it into the "motion" channel.
2. Then add a vectorBlur node.
3. In the VectorBlur change the UV Channels to the name of the motion vectors you previously copied into there.
4. Now increase the multiply to make it more or less motion blur.

01 January 2012, 02:45 PM

Look I tried with your method, but surely I am not understanding because it isn't working. I am rendering with 2d motion vector toxik, I think it was an error, because it is giving me many problems, for example I made this connection, it seems to work perfectly, but when I render it (it's a 2126 frames animation), at midway it stops, and then one of the vectorblur nodes changes to error, and the viewer tells me that VectorBlur3 (or 1 or 2 depends of the software spirit), cannot read the input vectors, and if you see inside the node the checkbox are MX and MY instead of the commons X and Y. I thought it was a problem only after render, but also when I'm working Nuke do it, I don't know what to, I will try to render in piecesl, close and open, I am going to see if it works. Regards.

Compositing softwares aren't my friends... :sad:

01 January 2012, 07:44 AM
I'm just curious why are you motion blurring all the render layers separately before compositing them together? Also why are you mixing reelsmart with vectorblur? They are going to have different results and probably won't comp properly

01 January 2012, 11:05 AM
well... I made different contribution maps inside a .exr file, each one with an own 2d toxik motion vector, I thought it was necessary to get a good result of blurring for each object in the scene... Look, I used automatic reelsmart for an little object because it was giving me problems with the alpha of the vector blur and his motion vector. How would you have proceed? Regards.

- Look, I just tried to use RSMB for all the animation, Do you know why RSMB give a so good result for all the animation without inserting motion vectors?

01 January 2012, 06:12 PM
RSMB uses optical flow motion estimation to create its own vectors based on the movement of each pixel in your animation. It usually works pretty well if you don't have a vector pass. The After Effects version has more tools to help it if it's not giving you the results you want. I wish they would port that part to Nuke.

02 February 2012, 12:10 AM
Well, I finally found the real problem... Vector Blur works perfectly with the tradional method, my problem was that I rendered a piece of my animation in other computer with maya 2011, then, when Nuke came to render this segment of animation it stopped, then I noticed there was not motion vector channel inside these frames. Now I am rendering this piece with my maya 2009, now everything goes fine. Regards.

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02 February 2012, 12:11 AM
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