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Author Topic: Reduce overlap feature  (Read 1135 times)

cbnewham

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Reduce overlap feature
« on: July 30, 2020, 02:16:09 PM »

I think the new feature for disabling images with a lot of overlap is a nice idea. Unfortunately, I have not found this of use. Even if I set the overlap allowance to "high", the resulting model is very noisy compared to using every image (image sets of the order of 800 to 1000 images).

I don't know the details of how the overlap is being determined (presumably by looking at the surface of the rough model that is needed in order to determine overlap, to see how much is shared between images).

It would be nice if there was an alternative method, which I think would work along the lines of removing cameras that have a close spatial distance and view orientation (perhaps ignoring rotation). For my cases, I think that would remove quite a few similar pictures without impacting the resulting model.


Alyssonsa

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Re: Reduce overlap feature
« Reply #1 on: August 07, 2020, 05:34:59 PM »
quote author=cbnewham link=topic=12426.msg55259#msg55259 date=1596107769]

I don't know the details of how the overlap is being determined (presumably by looking at the surface of the rough model that is needed in order to determine overlap, to see how much is shared between images).

[/quote]

I share this same concern that is brought by cbnewham! To me, the Reduce Overlap tool is very interesting, because I work with large datasets and this tool proved to enhance the pointcloud generation process. However, the fact that it is not explicit how this process is implemented in the software and what does high, medium and low accuracy exactly means, makes me wonder if I'm not losing some important information.

Does anyone knows which heuristic or algorithm the software uses for this overlap reduction?

gilrito

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Re: Reduce overlap feature
« Reply #2 on: September 24, 2020, 11:01:18 PM »
Dear all,

I found that this feature is very useful for reducing the number of images in facade inspection. If possible I would like to know the main idea behind this tool.
Thanks, Gil

simiyutin

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Re: Reduce overlap feature
« Reply #3 on: October 27, 2020, 03:44:43 PM »
Hello everyone!

In Metashape 1.7 pre-release Reduce overlap feature was updated and now uses more straightforward parameter: number of cameras per surface point. Now algorithm tries to select minimal set of cameras such that each point of rough model is observed from at least N significantly different angles(multiple cameras from single direction count as one) where N is specified by user. The new version is also approximately 100 times faster!

Previous algorithm used similar logic but with more complex formulation and weighting and was not as interpretable as the new one.

cbnewham

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Re: Reduce overlap feature
« Reply #4 on: October 27, 2020, 09:10:06 PM »
This sounds good. I look forward to trying it out.

 :)