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Author Topic: Suggestions for processing 360° horizontal imagery?  (Read 3815 times)

andyroo

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Suggestions for processing 360° horizontal imagery?
« on: April 26, 2013, 11:07:16 PM »
I just collected ~5 km of river data from a raft using 1-second intervalometer with a bunch of horizontal-looking cameras on a pole oriented to have about 30% overlap in the FOV and provide 360° coverage.

Now I have about 30 000 images to work with.  ;D  I am processing them in <5,000 image chunks, and my first one is aligning now (says it's got about 40 hours to go).

If anyone has done anything remotely similar, I am looking for recommendations on PhotoScan settings. I've done pretty much everything else with downward-looking imagery, so I am not really sure what's going to happen.

My goals are:

1. see what happens when I try to tie the imagery together.
2. If I can align and generate geometry, I want to make a DSM of the river bars and banks, and see what happens when I try to export an orthophoto generated from near-horizontal imagery.

3. Hoping to figure out how to generate a textured model and figure out how to either render a flythrough or allow people to navigate it.

4.  (kind of like 3) I think I might need to do video instead, since my cameras weren't synced, but it would be nice to figure out how to do something Google street-view-like.

Thanks for any suggestions/ideas..

Andy

frank.stremke

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Re: Suggestions for processing 360° horizontal imagery?
« Reply #1 on: April 27, 2013, 11:40:25 AM »
my expierience with orthophoto from shallow angle imagery is very bad very much disortet testures it actualy looks much better on the shaded object then on the textured. if the nummer of vertices is high enogh of course.

frank

RalfH

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Re: Suggestions for processing 360° horizontal imagery?
« Reply #2 on: April 27, 2013, 12:05:59 PM »
andyroo,

very intersting project. To begin with, I'd start small. That is, not use the entire length of the river but a shorter subset of the images to see how it works. As frank says, images taken at shallow angles are quite problematic , so I would't expect too much. A similar thing I have done was walk along a ~20 metre high ridge and just keep the shutter pressed as I walked along, taking images  of a field below. So this is a similar setup: many images taken at shallow angles along a roughly linear transect. Then I synchronised images with GPS positions and processed in Photoscan. The results were o.k. given the very limited effort I put into it. Main issues were: (1) relatively low resolution except for the foreground, (2) gaps in the model due to some areas obscured by others, (3) some texture distortion because of increased depth error due to shallow angles.

Re your other points: I would not use video because of the problems that come with this (rolling shutter, image compression etc.). Also, the same 5 km stretch of river could probably be covered by a single flight taking a few hundred aerial images at most. If you are aiming at the perspective of a person on the river, your approach may be better than flying, so I'd be curious to hear how successful you are.
« Last Edit: April 27, 2013, 12:15:39 PM by RalfH »