Forum : Technical Preview

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Topic: Out of order photos?

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isonicq (8 months ago)
I made a Walk synth and the photos are stitched together out of order, which makes it look weird. Is it possible to manipulate the EXIF data to make it recognize the correct order?
NateLawrence (8 months ago)
Could you link the rest of us to the walk, isonicq?

I looked on your profile http://photosynth.net/preview/users/isonicq but didn't see any listed synths.

Were the photos all taken with the same zoom level?
Were they all taken along the path in chronological order (so that if you sort them by filename, they would be in spatial order from beginning of the path to the end)?
PhotosynthTeam (8 months ago)
Photosynth tries to use the "Date taken" field to select order when it can.

If your photos were initially shot out of order, you can try clearing this field and reuploading. There is an option for doing this in the file properties in Windows. It's the link labeled "Remove Properties and Personal Information" at the bottom of the Details tab. Photosynth will then try to infer the order based on the 3D reconstruction.

Alternatively, you can artificially set the "Date taken" values to represent the ordering you want.
NateLawrence (8 months ago)
If the date captured information is important to you, you'll want to make a backup copy of your photos before deleting the metadata as that will be permanent.
isonicq (8 months ago)
This is the synth: http://photosynth.net/preview/view/ff3e05c6-29ef-4514-a722-5397fb9a5844

They were HDR photos (auto done in the camera), I don't know if that messed up the date, but looking at the date field, they seem to be in the correct order. Does the synth algo take into account the seconds it was taken, or does it only have a 1 minute resolution?
NateLawrence (8 months ago)
Ouch. 

One thing that is important to understand is that the new synths are more limited than original synths as far as shooting the scene however you want and stopping and looking off to the side of the road is not what a new 'walk' synth expects.

This does seem to be a particularly mangled reconstruction, though.
When you have the synth loaded, click or tap anywhere on it and type the [M] key to show an overhead map of the reconstructed camera positions.

You can also use the [C] key and then zoom out to see the camera positions in 3D.

Good question about the resolution of the time signature considered by Photosynth.

Photosynth team, what can you tell us?
PhotosynthTeam (8 months ago)
Nate is correct that this is a reconstruction failure as opposed to a camera ordering issue.

It appears to be caused by an erroneous match between two of the images. Try filling in the 35mm focal length field with a value of 23 (we're still missing focal lengths for a lot of phones, and Android models seem to be particularly bad about publishing these). This will restrict the degrees of freedom of the match verification and may help eliminate the match.
SCA_Chimera (5 months ago)
I had a similar issue. I took photos about every five steps on a walk through a building. That must have not been close enough together so that Photosynth couldn't associate images even though I can as the photographer. Is there a way to "force" the sequence of images, put them in order so that you can walk through? Here is the URL: http://photosynth.net/view.aspx?cid=0c6a4c14-699c-4bf6-b12c-71b3b6114442
PhotosynthTeam (5 months ago)
SCA_Chimera: Your "every 5 steps" should be shrunk to "every 1 step" if you want a smooth experience, or 2 steps if you are OK with a jumpy experience but expect a full reconstruction. Also, your URL is to an "original" Photosynth -- if you study the information about shooting a "walk", and reshoot this more densely then process with our preview technology you should get a good result.
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