Concerning GPS tags in EXIF data and the synther

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  • Updated 11 years ago
What is occurring, everybody?

I have, since before discovering Photosynth some time ago, liked the idea of cameras being equipped with GPS, compass, and gyroscope. I imagined the possibilities of photos embedded in digital globes and being able to reconstruct virtual camera moves between them, just as Photosynth does. I was quite enraptured by the idea, but of course I knew that positioning all the photos that have been taken before such position-recording equipment had been built into cameras was going to be a huge amount of work, not to mention inaccurate even after meticulous hours of tweaking a single photo. Then I found Photosynth and was instantly thrilled at the gap that it filled.

Fast forward a few years to present day and I am only now really dipping my toe into getting some images with GPS information embedded in their metadata.

I had two main questions:

1: Is it the case that the synther currently makes no use of GPS coordinates during scene reconstruction? Since Photosynth is mainly a computer vision problem, interested primarily (at this point in its life, seemingly) in using completely unaided computer vision techniques to match and position all the images fed into it, I assume that it does not take any GPS data embedded inside said images into account for scene reconstruction in interest of developing the most robust autonomous image feature matching.

I realise that there is some inaccuracy inherent in the GPS data provided by a camera or a separate digital compass (often being off by 5 metres). It seems like it would be, nevertheless, a useful jump start in scene reconstruction, where present - offering essentially a floorplan for the synth before any computation is performed at all. Direction and orientation would naturally still need to be solved for, but why not use the information where it is available or at least check the approximated camera positions calculated by the bundle adjuster to see whether they are within acceptable range of the provided GPS coordinates?

2: In cases where one does have a large number of images with GPS data embedded where said dataset covers a larger portion of ground and more photos than Photosynth can handle at once (especially if you have several overlapping takes of the same location), is there a tool that is capable of allowing you to select photos by geographic location or proximity to each other to then drag into Photosynth, rather than having to stare at the map, write out filename ranges, and then laboriously highlight those same ranges in Windows Explorer to then open in the synther?
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Nathanael Lawrence

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Posted 11 years ago

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