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Author Topic: Problems in dense cloud recostrution in extreme flat aea  (Read 2715 times)

tuffi

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Problems in dense cloud recostrution in extreme flat aea
« on: June 22, 2019, 07:27:33 PM »
Hi,

i'm try to recostruct an archeological excavations using ground based oblique photography.
But in the same area the cloud point have a "salt and pepper" effects (I attach a DEM screenshot where is more simply visible, red arrow indicate area with problems, and blue one the good area).

Someone have idea how to resolve the problems?

Thanks...

2bForgotten

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Re: Problems in dense cloud recostrution in extreme flat aea
« Reply #1 on: June 25, 2019, 11:56:33 AM »
Hi there,

Posted my question on the same subject (or problem ;)) here https://www.agisoft.com/forum/index.php?topic=10955.0

No really satisfying answers up till now  :-\

On Facebook I posted the same question and there someone suggested to use MeshLab to manually edit and flatten the mesh before creating DEM.
I haven't tried it yet.

Regards,
« Last Edit: June 25, 2019, 12:00:28 PM by 2bForgotten »

Alexey Pasumansky

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Re: Problems in dense cloud recostrution in extreme flat aea
« Reply #2 on: June 25, 2019, 01:22:23 PM »
The issue looks to be related to the alignment problems, like if there are several subsets of images aligned independently within the same project. 
Best regards,
Alexey Pasumansky,
Agisoft LLC

2bForgotten

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Re: Problems in dense cloud recostrution in extreme flat aea
« Reply #3 on: June 26, 2019, 11:59:51 AM »
The issue looks to be related to the alignment problems, like if there are several subsets of images aligned independently within the same project.

Hi Alexey,

No alignment problems in my cameras and no subsets. Just one set and all camera's did align.
Someone on Facebook suggested alignment problems too, so I added extra markers in all respective foto's but to no avail.

I would be happy is there would be a solution to this phenomenon though.

Regards,

JMR

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Re: Problems in dense cloud recostrution in extreme flat aea
« Reply #4 on: June 26, 2019, 04:19:47 PM »
Alignmen problems, I second that. Scroll right the ref pane table and check pixel errors for your photos. I you find images with errors greater than 1 pix, then you should check their alignment carefully. sometimes reset alignment of those poorly aligned photos and redoing alignment of the same, fixes problems. By the way, what camera/lens combo has been used? Could lens zoom have changed between shots?

tuffi

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Re: Problems in dense cloud recostrution in extreme flat aea
« Reply #5 on: June 30, 2019, 11:00:22 AM »
The issue looks to be related to the alignment problems, like if there are several subsets of images aligned independently within the same project.
Thank you, Maybe the problem could be the excessive overlap and number of images with no good geometrical distribution?
Maybe there are a way to perferm reduce overlap before the alignment process?