Forum : Bugs

Did the leaves fall off? Something not working right? Let us know how we can improve the Photosynth experience.


Topic: Against the laws of computing!

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Pierrot21 (Over 1 year ago)
I learned long times ago that: with the same data, a program should produce the same results ...
Photosynth seems to work differently ;-))
I tried this very, very simple 100% synth with 9 pictures only:
http://photosynth.net/view.aspx?cid=8896332a-fd16-4df6-bafd-e1f7f8620c04
and you feel like in a washing-machine                  but 2 minutes later, I got this one with the same pictures:
http://photosynth.net/view.aspx?cid=efe9fd29-c58b-4376-95b5-2a22aef5e996
which is nearly normal
WHY ?
I agree, I changed the thumbnail, but that should'nt make any difference, or does it?
madeeds (Over 1 year ago)
Some of the processing the synther does is not deterministic.  We are working on improving this in our upcoming releases.
PGRic (Over 1 year ago)
Pierrot, photosynth isn't alone on this front. Photogrammetric software is exactly the same, especially when pushing for mm accuracy on close range work. I think the algorithms are so complicated a few 1's & 0's get mixed up during the processing :-)
John_Galt (Over 1 year ago)
The photogrammetric processing should still provide equivelent results given the exact same input, it is simply a soultion to sets/blocks of linearized equations.  The desired precision scale should also have no impact on the result.  I am guessing the error is in the interest point extraction and matching, but its just a guess.
PGRic (Over 1 year ago)
you would think so John, but it certainly isn't the case on the photogrammetric apps i've used and tested.
bitplane (Over 1 year ago)
I guess the washing machine problem is because some of the pictures are taken from the exact same location but with different angles, giving false matches for positions (which show up as flat walls where the photos intersect). The difference in results may be due to the order in which the photos were added, the second set of images are equally as bad as the first but they have a more acceptable starting point
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