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Author Topic: Camera based chunks alingment  (Read 4860 times)

osima

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Camera based chunks alingment
« on: January 03, 2014, 03:38:49 PM »
Hi,

I have problems with understanding how the camera based chunks alignment works.

I have a project including several chunks. All the chunks include images from one camera (precalibrated, fixed), acquired from different positions. There are four images common to all the chunks (e.g.: A.jpg, B.jpg, C.jpg, D.jpg are present in every chunk).
When I select Workflow/Align chunks/Camera based alignment (fix scale unchecked), the chunks are not aligned as I would imagine they should be. In another words, after alignment the position of A.jpg, B.jpg, C.jpg, D.jpg from Chunk 1 is not the same as position of A.jpg B.jpg, C.jpg, D.jpg from Chunk 2 (they seem to be shifted).

Could someone shed some light on the camera based chunks alignment? I would like to understand what I do wrong.

Best regards,
Ola
 

JMR

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Re: Camera based chunks alingment
« Reply #1 on: January 04, 2014, 02:28:26 AM »
Hi, Osima: Have you made sure that chunk 1 is bold in the list within the chunk align dialog? if not double-click on it before alignment , this fixes it as anchor.
You might also have to check fix scale if you have already scaled the first chunk.

Regards

osima

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Re: Camera based chunks alingment
« Reply #2 on: January 04, 2014, 04:02:43 PM »
Hi JMR,

Yes, one of the chunks is bold (reference). None of the chunks is scaled at this point but I tried both options: with and without fixed scale, with no success.

Best,

Ola

Alexey Pasumansky

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Re: Camera based chunks alingment
« Reply #3 on: January 05, 2014, 02:37:51 PM »
Hello Olam

Could you please post a few screenshots of both chunks (with common cameras highlighted)?
Best regards,
Alexey Pasumansky,
Agisoft LLC

osima

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Re: Camera based chunks alingment
« Reply #4 on: January 13, 2014, 11:42:17 AM »
Hi Alexey,

Sorry for my late reply.
Please find the following screenshots attached:
Chunk1: chunk1.jpg
Chunk 2: chunk2.jpg
both chunks aligned and merged: chunks.jpg

This is the best that I could get so far (after removing 2-3 images common to both chunks). It seems like the positions of images common to both chunks are aligned but not their orientations.
Any ideas how could this be improved?

Best regards,
Aleksandra

Alexey Pasumansky

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Re: Camera based chunks alingment
« Reply #5 on: January 13, 2014, 11:52:54 AM »
Hello Aleksandra,

Thank you for providing the screenshots.

To improve the camera based alignment I can recommend to use non-linear flight segments with the common cameras for both chunks not positioned on the same line.

Alternative way is to reference and optimize each chunk based on the Ground Control Points in the same coordinate system, thus no chunk alignment procedure is required, since both chunks are already referenced in the same coordinate system.

Best regards,
Alexey Pasumansky,
Agisoft LLC