Question about ground control scene attribute, what is "uncertain"

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2 comments

  • Frank Warmerdam

    Ryan,

    We are not currently able to give a great metric for positional accuracy.  If ground_control is True we believe we are within our positional accuracy specification, while when it is False we are not at all confident.  It will be set to False in a number of cases:

     - we only have original satellite pointing information (often hundreds of meters off)

     - we only have positioning based on correcting the satellite pointing based on nearby scenes tie down. 

     - we only have control points tieing this scene to neighbours, but none directly to the ground reference. 

     - or lastly we only have a few tiedown points and our trust level in the result is low.

    If things being off by more than 10m is a problem, you should exclude anything with ground_control set to False.  We are contemplating offering more granularity of positional accuracy in the future, but we are still reviewing what would be possible and helpful.

     

    Best regards,

    Frank

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  • Ryan Avery

    Thanks Frank! we noticed a few outlier scenes over Ghana that were about 10 pixels or >30 meters off, we will try the boolean filter. 

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