JBinFla
lvl.1
United States
Offline
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Geebax Posted at 2018-9-21 15:33
That's all and OK, but DJI crop the image output and apply fish-eye correction among other distortions, so it would not be aan accurate image anyway.
Not true, the photogrammetric workflow has corrections for lens distortion and what you talk about. These corrections are calculated based on a least squares type adjustment. I've actually done this, not just read about it, and of course spent time in school covering the rather extensive math involved. Although difficult, for a computer and multiple images getting the correction factors for tilt, rotation, perspective, lens distortion, centering, etc. is a trivial task. Granted, sometimes it takes a while (hours) to process a set of data and produce the resultant orthophoto, but I've done this many times, and have compared it against high-accuracy surveyed control and proven reliably that with sound procedures getting this level of accuracy is not rocket science. I've done this many times. This is only possible with accurate lens parameters.
I'm not the only one doing it by the way. I've been surveying 20+ years and although I'm new to photogrammetry, I'm certainly qualified to measure to the 1/1000th of a meter and have done so and checked the resultant photos. I'm continually amazed at what the computer vision / photogrammetric data can do with enough photos and plenty overlap. |
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