helping when photosynth doesn't connect 2 photos

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Is there any way to help photosynth match photos?
for example, I ahd a bunch of photos. Photosynth couldn't find a connection between several of them where the connection was evident to me. Is there a way to help photosynth?
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Huck Rorick

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Posted 10 years ago

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Nathanael Lawrence

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Hi, Huck.

Sadly, the answer is no; there is no way to manually connect photos which Photosynth did not match automatically.

If you're really interested in using Photosynth, what you soon realize, after seeing some of the synths which other people have been able to build with it, is that you are just going to need to change the manner in which you photograph a scene.

Put very briefly, most people don't overlap their photos enough when they begin making photosynths (I know I didn't when I began). When you first hear this, it's easy to think, "I just need to overlap the edges of my photos more, then.".

I actually think that's misleading. I would say, instead, focus on getting the center of your photos to overlap and don't worry about about the edges overlapping so much.". One very easy to remember way of doing this is to walk in a circle around each thing in the scene which you care about seeing in the synth's point cloud.

There's nothing magical about a circular camera motion, but this will help you give Photosynth a good description of how things look from almost any direction. Once you've described some objects by taking photos around them, just take some photos looking from one to the next and walking from one to another if they're a ways apart from each other.

For much more explanation on this, please read this discussion.
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Nathanael Lawrence

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If you would still very much like to try manually correcting alignment after a program tries to automatically connect your photos (perhaps you are unable to visit the original location, where the photos you have were taken, to take photos between the positions that didn't automatically connect the first time or perhaps the original location has changed appearance too much since your existing photos were taken to automatically match), look up:

Autodesk Photo Scene Editor and Project Photofly

The open source insight3D project.
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Huck Rorick

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Thanks for the response.
I had one case that was a little puzzling. I had pictures of a building and then a picture of a detail. Photosynth couldn't match them up. I'm not sure why but it defeated the purpose of the synth.

I would be a little worried working with the Autodesk system because it says it works for a limited time and I would guess they would start charging (usually a lot) after a while. I would be concerned about investing time in learning and using a system and then losing access to it. any thoughts on that?

Huck
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Nathanael Lawrence

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As to the Photosynth case of the detail not matching the more distant view of a building, I would just ask if the part in the detail shot was more than twice as big as in the next closest shot of it. The Photosynth Photography Guide says on page 2, "A good rule of thumb is to never move more than half the distance to your subject without taking an additional shot. Similarly, never increase your focal length by more than a factor of 2 without taking an additional shot."

It would help to be able to see exactly what you're talking about. If you haven't deleted the synth, load it up, find the detail shot, then while you're in 3D view click the 'Share' link underneath the synth and paste the exact link that it gives you back into this discussion which will allow me to see the exact photo that you are talking about.

One possibility of getting a detail shot to match a wide angle is (provided that the source photos are of decent resolution) to take the wide angle shot, create a copy, and then crop so that the portion of the scene that appears in the detail shot takes up more of the frame in the crop of the copy of the original than the original wide angle but less of the frame than the close up. Credit goes to Ken Perkins on the Photosynth team for pointing this little trick out back in 2008.

As to the fact that Autodesk's Photofly and Photo Scene Editor are a free labs experiment now and will undoubtedly become a paid product some time in the future, my perspective would just be to enjoy it while it's free and keep an eye open for other solutions so that when it's moved out of Autodesk Labs, you may already have found an alternative.

To be honest, it will serve you better to learn how to shoot so that it is almost guaranteed that the computer will match things rather than depending on a tool to manually place photos that didn't match or matched weakly. The only real exception is if it is literally impossible to ever reshoot intermediate shots between the unmatched shots.
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Huck Rorick

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Here are 2 cases where the detail wasn't matched up. I think your comment about 2X max magnification between shots.
http://photosynth.net/view.aspx?cid=4...

and another, probably same problem
http://photosynth.net/view.aspx?cid=3...

Huck