In Nuke, you need to use VectorBlur node. ( under Filter menu )
The VectorBlur node has just one single input. This means the input source image must carry its own motion data, in this case, the separately rendered out 2d motion vector pass.
To do this, you need a ShuffleCopy node ( under channel ).
Check out the connection.
And set up the node like it's seen in Pic_2. Notice that the R and G channel of the 2d Motion vector image feed the u and v motion channel of the Masterbeauty pass.
Now it's time to look into the VectorBlur node.
1. Set the uv channels to motion.
2. Type in -0.49606 for add uv. (This value can be generated from the following equation. )
3. Set method to forward
4. Select rgba.alpha for alpha to enable it.
5. Try some values for multiply to see if it works.
Here's the final result. Click to see the animation.
|Final : 2d motion blur applied|
By the way, I would recommend using EXR format for 2d motion vector pass to ensure precision.