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Author Topic: Difference between "Matching Points" and "Selecting Pairs"  (Read 3755 times)

hanparker

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Difference between "Matching Points" and "Selecting Pairs"
« on: September 17, 2015, 08:09:49 PM »
I'm going round in circles a bit at the moment - sorry if I ask stupid questions.

I have an awful lot of data to process. I am running two Professional licenses of Photoscan on AWS - I am connecting via VNC so that I can use the GPU on the remote devices. The remote devices have 4 GPU. I am processing chunks of around 800 photos at a time. The "Align Photos" stage has been taking around 2 hours. I give it the x,y,x pitch, yaw and roll info via a txt import and the camera calibration I set via a python script.

What might cause the "Align Photos" stage to take a lot longer than usual? I've set a job going and it is predicting that the Align photos stage will take 10 hours. The data is stored on a local drive so it's not a network issue.

I have "fixed calibration" unchecked in the "camera calibration" screen for the sensors - does that make any difference?

I am running a similar data set on my home pc (not identical though - photos from a different part of the survey) - this says it is going to take 27 minutes at the stage immediately after the "detecting points" stage of "align photos" - but instead of saying "Matching Points" as the remote PC is saying, it says "Selecting pairs" - is there a magic option that I have selected by accident on my home pc that I've not set on the remote one?

I have previously run successful models on the remote machines in the same sort of timescales as my home one so I know the hardware configuration is up to it and presume I've done something wrong. I've checked the preferences screen and I am using 28 of the 32 cores and all 4 GPU (though I know these are used for the dense point cloud stage rather than this initial stage.)

Any hints and tips will be gratefully received.







Paulo

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Re: Difference between "Matching Points" and "Selecting Pairs"
« Reply #1 on: September 17, 2015, 08:20:01 PM »
If you have georefernce info for your cameras then in Align Photos be sure to set pair preselection option to reference and not disabled. This will speed up the process as it will use camera positions (XYZ) to preselect image pairs to match and align
Best Regards,
Paul Pelletier,
Surveyor

hanparker

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Re: Difference between "Matching Points" and "Selecting Pairs"
« Reply #2 on: September 17, 2015, 09:25:01 PM »
Thank you! I think you might have saved my sanity. That looks like a much more promising timescale now I've selected "referenced".