SIGGRAPH 2008, and image editing in the gradient domain

I just got back from my last visit to the west coast, this time for SIGGRAPH 2008. Unlike the other years I’ve been at SIGGRAPH, this time I was working, so I didn’t really have that much time to sit through technical talks. However, I did see a few talks and flipped through a few of the papers on the proceedings.

Let me start with the best talk I’ve seen in a long time. Real-time Gradient-domain Painting, J. McCann and N. Pollard. The presentation consisted of many, many live demos of the work and the techniques (using his own presentation software). This included intuitive explanations of the Poisson’s equation approach to image processing in the gradient domain, interactive diagrams of how multigrid solvers work, and other cool stuff. In particular, he wrote his own presentation software, and it just blows everything else I’ve seen out of the water (it reminded me of Alan Kay’s Squeak talks, only with decently rendered fonts). It’s hard to describe: if you can get your hands into the DVD video recordings, do so. It’s worth half an hour of your time.

The really refreshing part about the talk was that it had a great point of view: painting a small area at a time is a limitation of the physical world that’s just not there in a computer. We should do better than that, and they do it by letting the user paint desired edge changes in the image, and using the incredibly useful Poisson equation framework originally proposed by Perez et al. five years ago (yes, Adobe, I know about the healing brush). You should go check this paper out.

Back when I was an undergrad, I had the opportunity to monkey around with a really simple application of this method. At the time, Manuel Oliveira and my advisor were working on GPU relief mapping, and realized that the Doom 3 engine makes extensive use of normal maps, and that he needed depth maps instead for relief mapping. We quickly put together a solver that did a decent job of reconstructing the depth information. After a fair amount of hacking (of which I wasn’t a part, unfortunately), he and his collaborator now have a plugin for Doom 3 Quake 4 running with relief maps. Check it out (wmv, unfortunately. Edit: Fixed link), it’s pretty cool – they even get self-occlusion and shadowing right, in texture space.

The other cool SIGGRAPH papers I’ve seen or read about are Lipman et al.’s deformation paper and Snavely et al.’s (slashdotted) video enhancement paper. More on those soon.

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2 responses to “SIGGRAPH 2008, and image editing in the gradient domain

  1. I’ve just stumbled upon your blog and am enjoying reading it. BTW, your last link has one too many “http”s on it…

  2. carlosscheidegger

    Thanks for the heads up on the link – it is now fixed.

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