Working with large photo sets.

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  • Updated 11 years ago
Suppose that Christopher Robin walks through the 100 acre wood, stopping every 50 feet and takes 5 pictures, NSEW and up, with the focal length of the camera set so that each photo overlaps the 3 around it. He criss crosses the forest twice. Of course his camera records the GPS coordinates too.

From this could Winnie traverse a virtual diagonal path through the wood?
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Sherwood Botsford

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Posted 11 years ago

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David Gedye, Principal Group Manager

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Eeyore says: Hopefully in the future - but not yet.

In this release you are practically limited to a few hundred photos per synth. In later updates we hope to give you the ability to stitch synths together, and then walk them seamlessly.This scenario should* work then.

*Caveat: The hundred acre wood and other heavily forested areas will always be a challenge to the kind of computer vision algorithms that Photosynth uses. The amount of occlusion in a forest is significant, and this in general confuses Photosynth. If you substitute the hundred acre wood for the ten mile beach, I think the answer will definitely be yes.
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Gabriel Walsh

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Okay, the funniest thing about your question is not at all what most people will think upon first, the funniest part of your question is that someone named Sherwood is asking a Forest question! That is priceless!

That said, and David’s very relevant Caveat notwithstanding for the moment, your inquiry made me wonder just what your hypothetical might actually require to accomplish in terms of time, photos, distance, etc., so here’s my attempt at some basic math.

- An Acre is about 44,000 sq. ft. That means the Hundred Acre Wood comes in at about 4,400,000 sq. ft.

- Assuming the Wood was a perfect square (which I don’t think it was, but the math should stay pretty much the same anyway), that makes it about 2,100 ft on a side.

- Based on your “every 50 feet” specification, that means there would be about 42 photo opportunities per pass, with about 42 passes, for a total of 1,764 photo opps.

- Based on your “5 photos” per stop specification, that makes about 8.820 photos per full coverage pass of the Wood.

- At this point, you mention making two criss-cross passes of the wood, but I have to ask you a question...if you are taking pictures in all directions, what good would a second pass really do? If you are looking for more overlap, why not just take 8 photos per stop and save yourself the extra pass? If you are looking to criss cross in opposite directions, won’t you still end up in essentially the same photo spots? If not, then why not either a) shoot NE, SE, SW, NW at each stop also, or b) stop every 25 feet? For argument’s sake though, let’s assume the two passes you hypothesize at the outset: that makes for a total of 17,640 photos.

- At about 5MB each (10-12 Megapixels, I assume?), that’s about 88 GB of storage.

- As for the distance/time, assuming 42 – 2100 ft passes, you’re looking at about 17 miles per pass, for a total of about 34 miles of walking.

- Assuming an average walking pace of about 3 MPH, you’re looking at just over 11 hours of walking

- We still need to add in photo time, so even if you’re really quick, I think we need to bank on at least 5 seconds per shot (this is a very low estimate, but no reason to exaggerate here, right!? ;) . This equates to about 24 hours straight taking pictures.

- Total time: approximately 35 hours.

Which leaves me with a few parting thoughts:

- If a photographer falls in the forest, does he make a sound?

- Maybe you should think about synthing the Honey Tree first? Or Tigger? (Stripes are good for synthing, I Imagine!)

Good luck on your quest!

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Ken, Official Rep

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I took the question as more aimed at the creation of synthetic views. Something like "If I followed all these complex steps could Photosynth create new views of the diagonal path?". The answer is no, it would not create a synthetic diagonal view.

Remember that at the center of the screen Photosynth is always displaying an image that you took. We use other images for transitions and to provide context but we always move from image to image.