KAP Aerial Archaeology and Photosynth

I've been frustrated in my attempts to turn KAP aerial archaeology shots into maps, or even into stitched panoramas that bear any real resemblance to reality. For the most part this is because I really don't have the right tools to get the job done. Photogrammetry, and georectification are not simple to do, and most consumer-level tools aren't suited to the job. Typically this involves software like Photomodeler, Leica Photogrammetry Suite, and GIS software. It also typically requires a grid of GPS-referenced ground control points. I'm not positioned to do any of these things.

But I did run across something that produced oddly pleasing results. It's a Microsoft R&D product called Photosynth. It's not so much stitching software (though I use Microsoft's Image Composite Editor for most of my stitching these days). Instead, Photosynth assumes the shots are not taken from the same vantage point, and finds all the points at which the shots overlap. This in turn is used to create a point cloud of intersection points between shots, so a viewer can place themselves at any of the vantage points from which the photos were taken, and see the scene from that point.

All of which is hard to say, but a lot easier to see. I tried this out using one of the flights from last weekend:

It worked remarkably well. Even more fun is to view it with the images turned off so you only see the point cloud of the intersection points between all the shots. Photosynth does a really good job of picking up the three-dimensional structure of the scene.

I tried it with some of my other KAP flights, just on a whim. The archaeology flights were almost all orthogonal to the ground, but most of the time when I'm out doing KAP I'm busy taking oblique shots rather than orthos. I was amazed at how well Photosynth dealt with this:




I think there's a lot of potential for what Photosynth is doing. There are all sorts of other features I'd ask for (and have asked for) beyond the existing Photosynth interface. Among others, it's ideally suited for picking out proper stereo pairs from a whole collection of images. It would be wonderful to have them all gathered, arranged, cropped, and ready to go.

Even better would be 3D model extraction from a random collection of photos of a scene. One KAP flighti n particular resulted in a really good point cloud for a large truck: a deuce-and-a-half. I'd love to be able to export that truck as a 3D model.

I don't know how much time I'll devote to this, but right now it's pretty fun. And for now walking around an archaeological site using my aerial still shots is as close as I can come to what i want: real 3D scene reconstruction.

-- Tom