Amazing Compositing Without Tracking? Using Vector Warp in DaVinci Resolve

Written By Juan Pablo Martínez

Learn how to use DaVinci Resolve’s Vector Warp and Optical Flow nodes to place logos, tattoos, paint fixes, and graphic elements onto wrinkled or deforming surfaces inside Fusion.

How to make flat graphics move with the fabric

If you have ever tried to place a logo on a shirt, tent, jacket, or any wrinkled surface, you already know the problem.

A normal transform gets you part of the way there. A corner pin can help if the surface is mostly flat. A tracker can follow one or two points. But clothing is not a flat billboard. It stretches, folds, wrinkles, catches highlights, falls into shadows, and changes shape again two frames later. It only way to properly composite this is by making a mesh made out of multiple tracking points. Or so I thought, you don’t even need to track anything at all. At least not in the usual way we understand tracking.

That is where DaVinci Resolve’s Vector Warp node gets interesting. The Vector Warp lets you take an image and distort it using the movement from the original footage. Instead of manually tracking a bunch of points, you use Optical Flow to generate motion vectors, then feed those vectors into Vector Warp so the graphic follows the surface. When it works, it almost feels like cheating. You don’t have to fix manually any tracking points. Just let it run and done. And no, this is not AI. It is image analysis.

Resolve analyzes how pixels move from frame to frame. That movement becomes vector information. Vector Warp then uses that information to push, bend, and distort another image so it follows the same motion. It’s actually very similar to using a displacement node.

Both Optical Flow and the Vector Warp node used to be only accesible on high end, and very costly software, like The Foundry’s Nuke. What a time to be an artist!

Start in DaVinci Resolve, select your clip, and open it in Fusion. Then F2 on media in node to rename it. I like renaming as a I go otherwise your comp starts growing and the node tree becomes spaghetti. Bring your logo into Fusion and merge it over the original plate so you can see the placement.

If the logo’s resolution is too big, use a Letterbox node to make it comp size Then add a Transform node to scale and position it where you want it. If your logo is 3000px by 3000px it should fix that to your preferred comp resolution.

Logo -> Transform >Letterbox-> VectorWarp (green)

Now select the original plate and add an Optical Flow node. To check if it is working, view the Optical Flow output and switch the viewer to show vectors. You should see a color-coded representation of movement instead of the normal image.

After Optical Flow, add Vector Warp through the yellow input and then connect the logo to the green input of the Vector warp node.

Original_Plate -> OpticalFlow -> VectorWarp (yellow)

The logo should move correctly and you can now freely work on the logo’s compositing. A simple trick is setting the blend mode to Overlay. This lets some of the shadows and highlights from the plate come through the graphic, so it feels less like a flat PNG sitting on top of footage. But I like taking it a little further.

One trick I picked up from Chadwick Shoults at Video Creative Tips is to remove the color from the original plate only underneath the logo, then place the logo over that area using a blend mode like Overlay. The point is to keep the contrast from the fabric without letting the original colors contaminate the logo (which you might want or not depending on the scene).

Important limitations

Vector Warp does not truly understand 3D. It is following motion vectors from the image. That means it can struggle with big perspective changes, heavy occlusion, motion blur, compression artifacts, flicker, fabric folding over itself, or foreground objects obscuring the surface.

For serious 2.5 or 3D movement, use the Surface Tracker, Mocha Pro. For some cloth or flag shots, a displacement setup may look better because the movement is too chaotic for the clean vector warp. You will get a feel for it over time and understand it’s just another tool in teh VFX arsenal.

 

Sources

Juan Pablo Martínez
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