Forum : Mobile Photosynth

Share tips for making and sharing amazing panoramas from your phone.


Topic: Trouble with 360 on iPhone app

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curiousdy (Over 1 year ago)
Hi.  Last week, I used the app without any significant problems.  I was very impressed even though I had some exposure issues.  Today, I was showing my coworkers the app and noticed that I could only take 270 degrees before the first picture appeared so I couldn't take the last 90 degrees.  I turned off the phone and back on again and still got the same problem.  Is there something I am doing that is amiss?
curiousdy (Over 1 year ago)
I just tried it outside and it worked a little better.  I noticed that the app has problems with objects that are a few feet from me as well as with indoor pictures.  Is the 270 degrees vs 360 degrees an issue with indoor pictures?  I'm figuring that the nearby objects is a common problem.
Nathanael (Over 1 year ago)
Hi, Curiousdy,

I can't speak to your problem with the panorama catching its tail too soon, but I might be able to help you understand a little more about shooting panos.

Panorama stitching is essentially 2D stitching. This is what the Photosynth mobile pano app is doing (and is different to what the desktop version of Photosynth does). What I mean is that panorama stitching programs expect that every object in the input photos line up the exact same way in all the photos and the stitcher is really just an automated way of lining all the different photos up. You may realise when you read that that panorama stitchers do not know what to do when a foreground object lines up with a background object differently in different input photos. This usually results in either two copies of something or half of something being chopped off, as the panorama stitcher attempts to get a complete outline of one of the objects.
Nathanael (Over 1 year ago)
No matter what pano stitching app you're using, an experienced panorama photographer will always attempt to keep the camera's lens in the exact same place in the air when taking photos.

The more you move the camera's lens between input shots, the more stitching errors you will get in your panorama. As you figured out above, this parallax effect affects foreground objects more than background objects. This is not because parallax goes away with distance (if I raised my hand above my head and you looked at what my hand lined up with behind me as you moved 3 metres to the left and then 3 metres to the right of me, there would still be a difference, whether I was standing 10 metres from you or 100 metres from you) however because distant objects comprise a much smaller number of pixels, it is not nearly as noticable.
TonyErnst (Over 1 year ago)
curiousdy - I suspect you may be running into one of two issues.  The first could be that your moving the phone around your body instead of you body around the phone leading to parallax - this video will describes what Im talking about and how to get around it: http://www.youtube.com/watch?v=6XYSJPbwBT4&feature=player_embedded

The other possibility is that your office walls are painted flat color and there aren't any "features" for the app to grab and figure out how everything relates to each other.  If this is the case there's not much you can do except tack a few posters on the walls :-)
Nathanael (Over 1 year ago)
Here are two quick video tutorials which stress the importance of keeping the camera's lens in one spot: 

AutoStitch: http://www.youtube.com/watch?v=svVq7dx_pDY
Photosynth: http://www.youtube.com/watch?v=6XYSJPbwBT4

If you ever decide to try to shoot photosynths (to stitch with the desktop Photosynth program) instead of panoramas, moving the camera around is very important and the process is very different to taking a pano. You can read more about that here: http://bit.ly/shootingforreconstruction
curiousdy (Over 1 year ago)
Thanks for the replies.  I'll try that.  I was pivoting myself rather than using the camera as the axis point.  Is it better to shoot horizontal to the horizon or in columns perpendicular to the horizon?
Nathanael (Over 1 year ago)
Shooting in columns is convenient if you have people walking around because you can catch them in one place. Another advantage is that you can more easily capture the entire view of that direction while making sure that the camera isn't moving. The truth is that it's pretty tough to keep the lens in one spot as you're turning around, so you may as well capture as much as possible at each of your feet's positions to keep the lens' movements as minimal as possible. Really, though, you should use whatever is easiest for you at the time and whatever best fits your subject.

If I were shooting a tall building with an external elevator, I might want to shoot in rows instead of columns so that the elevator only appears at one place in the pano. The same would go for any other scene with a lot of vertical movement.

I hope that helps! =)
Nathanael (Over 1 year ago)
Hmm. I just reread your question and now realize that it was more about the portrait mode versus landscape mode. 

Any suggestions, Tony? Perhaps giving some scenarios where each orientation is most appropriate and reasons why that is, or explaining which is better for a quick capture versus a more detailed capture (if it makes a difference) would make for a good subject for episode 2 of the mastering the Photosynth mobile app video tutorial series.
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