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Sunday 24 August 2008

Microsoft Labs Photosynth - got any tips? [Beej]

Photosynth from Microsoft Labs has been viewable for about a year, but this week it went live and users can now upload their own 3D synths.

You'll know Photosynth from that 2007 demo when the smart chap from MS wowed us with Venice.

After excitedly browsing Photosynth, I found that it's all pretty lame. Like a guy who did St Pauls Cathedral from the same spot on the street and took 9 photos. So it being a bank holiday weekend, I've given it a swizz myself!
  • I chose MINI as the subject... couldn't think of a small enough local landmark
  • I took nearly 400 lores (1024x768) photos walking around the car and inside the car, and of the tree and low moss-covered wall beside the road
  • Processing took nearly an hour on an E6600, and the app said that more than 300 photos is not necessarily good.
  • It has not gone well, though... the synth was 47% "successful" ;-(
My first test synth can be viewed here: Beej's MINI Cooper S (2003)

One of my problems with Photosynth is the interface, so some tips:
  • press P to cycle viewmodes of points/images/both
  • mousewheel to zoom in/out
  • the leaf icon with three dots (in the corner) is very useful - it jumps to areas where it made good matches - press it once to jump to the stick that was near the wall
  • the grid view icon is the only way I can find to get to the tree on the right side of the car. It has done an incredible job at mapping the tree in 3D! Make sure you view it in points mode :)

So, it's not really gone as well as I had hoped. Admittedly, a metallic reflective two-colour car... a building might well be the ideal subject.

IMO the UI is not helping Photosynth though, nor is the basic navigation in the virtual environment. How is it not possible to get from the front to the back of the car?

Zoom out in points view. All the way. It's quite interesting. it has done the side of the road better than the car!

The RTFM, which I'd read beforehand, recommends at least 9 photos for the corner of a building. It also recommends stepped close/far linear shooting for going along a flat object like a wall. In both cases, a lot of overlap.

It was hard to break the habit of shooting for a digicam panorama - not enough overlap - and also shooting for texture maps. Both are bad practices AFAIK.

Photosynth seems to be better suited to a public space with public harvested photos - like the Venice demo - where the photos were taken from flickr. Next test - a building - but look forward to one of you trying an inside room!


  1. Very cool stuff!

    I had a play around with it this morning. My first attempt turned out with a disappointing 7% synthy value. This was only 50 photos though, and I think I put too much thought into them. So I cast off the usual digicam way of thinking, turned off the image preview on the camera and just went snap crazy, taking 250+ random photos of absolutely everything in the room.

    Here's the results: Conservatory.

    75% synthy and very impressive. Incidentally, this took about two hours to render on an EEE 901 Atom processor. Ugh.


  2. Hmm, having looked at some of the examples on the photosynth site, I'm less enthused about about this than I was. The technology is definitely very impressive, I just can't really see a use for it. I think a big part of the problem is that the public seem to be completely missing the point - uploading pictures of their kids moving around, for example. Photosynth seems to be well suited to static scenes - rooms, or buildings. Anything that moves or has a narrative is not going to work very well.

    I suppose it needs padding out somewhat - the ability to annotate scenes would be very useful, being able to tag interesting items or features to zoom into. Also, the ability to take pictures from multiple sources and automatically incorporate these into the scene.