Quick Tip: Refine SmartVectors with an STMap.
SmartVectors, and the associated VectorDistort node is one of the best new additions to Nuke in recent years. Being able to effortlessly track a texture to an organically-moving object is amazing when it works, but oftentimes SmartVectors only gets us part of the way there and needs refinement...
By changing the VectorDistort's Output knob to "st-map", we gain the ability to modify SmartVectors in a bunch of ways, before using an STMap node to apply the modified warp to the image (as you see in the setup pictured below).
For example:
If a track slips off in a section: Isolate the problem area with a rotoshape, and adjust the warp with an iTransform. Blurring the rotoshape will give you a nice, smooth transition between the VectorDistort & your extra warp!
If a track is slightly jittery: Add a blur to the problem area. Blurring the st-map averages the pixels, and therefore averages out the motion.
If you want to blend between two SmartVectors: You can simply _Dissolve _between the two st-maps!
Working with SmartVectors this way adds an exponential amount of extra power into an already powerful tool. How else could you utilize this technique?