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Author Topic: Unexpected results  (Read 2154 times)

pbourke

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Unexpected results
« on: June 03, 2019, 09:36:37 AM »
I'm a long time PhotoScan / MetaShape user.
I've started a project scanning small objects, around 1cm-2cm on their longest axis. For this I am using the Canon MP-E65mm 1:1 to 1.5 macro lens, but mostly using between 1:1 to 1:2 magnification.
The first few worked (eventually) but if they work seems a bit random despite not changing my protocol. I am doing the objects in two halves, lots of overlap and merge by markers. I do not touch the lens after I start, focus is manual on a slider rail.
I am using a motorised platter in a light box and I mask all images.
I set photo-invariant parameters to all, lens characteristics don't change.
I set camera calibration to auto and adaptive cameras in photo alignment.
The first few worked fine, but in the latest batch 2 do not, despite me not doing anything different (that I know).
See typical screen shots after photo alignment, lots of keypoints. The camera positions are 90% correct but not all, in the attached there are some cameras on the right incorrectly assigned to near the top.
Ideas on how to configure MetaShape options for this type of work?
Photographic reconstruction portfolio
http://paulbourke.net/reconstruction/portfolio/

pbourke

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Re: Unexpected results
« Reply #1 on: June 03, 2019, 09:43:59 AM »
Just a further comment to say I am aware of the depth of focus issues. I rotate the specimen around in 20 degree steps and focus on either the forward rim or the back rim, I do this for 3,4,5 heights depending on the object geometry. I imagine there is lots of in focus areas between the adjacent images and between the heights.
Photographic reconstruction portfolio
http://paulbourke.net/reconstruction/portfolio/

Eichhorn18

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Re: Unexpected results
« Reply #2 on: June 03, 2019, 05:21:39 PM »
Just a further comment to say I am aware of the depth of focus issues. I rotate the specimen around in 20 degree steps and focus on either the forward rim or the back rim, I do this for 3,4,5 heights depending on the object geometry. I imagine there is lots of in focus areas between the adjacent images and between the heights.

Can you share one of the individual images used for the reconstruction?

pbourke

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Re: Unexpected results
« Reply #3 on: June 04, 2019, 06:05:51 AM »
When I set point alignment accuracy to "highest" then all seems fine, except for the time it takes. :-)
Photographic reconstruction portfolio
http://paulbourke.net/reconstruction/portfolio/