Question about ground control scene attribute, what is "uncertain"
What constitute "uncertain" for this attribute? 3 pixels off? 10 pixels off? It would be helpful to have a numerical representation of positional accuracy rather than a boolean so that we could filter by the positional accuracy we need. From https://developers.planet.com/docs/api/psscene4band/
ground_control |
Positional accuracy of the item. If the item has uncertain positional accuracy, this value will be false. |
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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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