Darren New wrote:
> http://www.youtube.com/watch?v=TuHJUS2olyc
> 
> Cool. Use Photosynth to take a bunch of pictures and turn it into a 3D 
> model.
> 
> I saw how to do something like this like 25 years ago, in Byte magazine 
> or something, using a digitizer (what we'd call a graphics tablet today) 
> on a few pictures to identify the common points. Never really followed 
> the math, unfortunately.
> 
> Anyone know what the math behind "here's a bunch of 2D images, figure 
> out the 3D shape" is called?

The technique used by Photosynth is called "structure from motion". 
Also the method shown in the video almost certainly will not work well 
for a wide range (probably most) Photosynth scenes.  It's probably only 
actually useful for cases (such as described in the video, to its 
credit) where you're taking all the photos yourself and thus can go back 
and get more to fill in any areas where you missed.  It probably also 
won't work well on scenes without a lot of surface texture, with 
transparent or reflective surfaces, or where the small-scale accuracy is 
important (such as on most architectural scenes).  So basically, don't 
get too excited, there's a reason why you haven't seen any major demos 
of getting 3D models from Photosynth yet.

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