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Maps positioning


During the last days I processed 16 maps with MME. After checking them with the client, we noticed that 6 of them are well off position when viewing them in Google Earth pro against a KMZ file which has centimeter level positioning of structures on ground measured by Geodesic GPS on ground. We are talking here of +-18m, while the other 10 are pretty much very close to the KMZ structures.

To verify processing I decided to process 1 map again and when comparing it with its previous processing, even the positioning is different between them, while they have been processed in the same way and with the same data (231017_AJBC_T2B_E30-31 and 231017_AJBC_T2B_E30-31 Prueba).

Could you please give us a reasoning behind the 6 maps that are well off positioning and why the map that was processed twice has different positioning? We understand that DJI GPS has 2-5m error but these are well off those parameters and the map that was processed twice has even different results.


Tomás Valenzuela

Official comment


Linear data has recommendations in the Data Collection guidelines that are not being followed:

  • Job Shape - When doing long, linear jobs, make sure to do AT LEAST three passes so there are enough perspectives to reconstruct the scene. Increased overlap will need to be used to make up for the lost width. When doing few passes don't do a straight line. Either put a kink in it or use more passes.
  • Overlap - The more, the better. (18-25 views of everything is good, 40 is too many) Along track and across track overlap should exceed 70%. More complex scenes require more overlap (80-83%).

You want your overlap report to show mostly dark blue (16+ looks). You need more passes or much higher overlap settings to do that. Also, throw a kink in the shape. 

You will get better and more accurate results if these are followed. Some of your data looks OK and that is the data with the better (more blue) overlap reports. 

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