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Topics - schermer

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Camera Calibration / Camera calibration for historical air photos
« on: February 26, 2020, 01:54:56 AM »
Hi.  I'm new to photogrammetry and have been having trouble getting good alignment for series of aerial photos (e.g. USGS and similar). I have been cropping the black edges off the photos before I load them into metashape pro.  I add GCPs after the initial alignment, and optimize the cameras.  The alignment is pretty good, but I often get some camera locations that are at a different height than adjacent ones, even though presumably the flight was at a similar elevation for the whole photo strip.  Also the calculated focal lengths are not the same (or sometimes even close) to the focal length given in the metadata.  Is there a way to fix the focal length or the camera height for all the photos in a chunk so that the alignment is improved?  For most of these photos I don't have complete camera information, just focal length, scale of photo, and approximate center and corner positions.  I tried entering the focal length (in mm) in the camera calibration tool, but then when I "optimize cameras" again, nothing seems to change.  Thanks for any help you can give!

General / Building orthomosaic causes photoscan to crash
« on: November 11, 2019, 02:20:36 PM »
I have been trying to build orthomosaics from DEMs and when I try to reset the boundaries or resolution (I need to make several different files with the same grid size), the program crashes.  It seems to work fine if I don't reset the boundaries, or if I reset the boundaries during Export Orthomosaic.  I want to be sure that the orthomosaics can be compared exactly (they are before and after images of a site); does setting the resolution and boundaries during export accomplish the same thing as buildng an orthomosaic with these parameters?  Why does the program crash during the build command?  I can send the error message if needed.

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