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ImageStation powers high volume photogrammetry and production mapping workflows.
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The customer has done ISAT and tried to check its quality. Why sigma in Control Panel is different form that in "result" button. Which one is true?

by ddoud on ‎03-14-2016 01:02 PM (330 Views)

Question

The customer has done ISAT and tried to check its quality. Why sigma in Control Panel is different form that in "result" button. Which one is true?

Answer

ISAT must use the EO_Parameters from the photo file to approximate, then compute the bundle adjustment. If the data is not GPS/IMU quality the program "floats" the standard deviations of the EO values to 10% of the flying height in order to assure a solution. The sigma reported on the Control Panel reflects this very loose weighting scheme. Later, when the user begins to evaluate the results and runs the bundle adjustment in PhotoT the actual standard deviations from the photo file, which are generally much tighter, are used causing a more realistic final computation, that is, as long as the standard deviations assigned are realistic.
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