Author Topic: Alignment issuse after adding GCPs  (Read 1127 times)


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Alignment issuse after adding GCPs
« on: May 29, 2020, 02:30:15 AM »
Hi, when I processed different sets of  multispectral (RedEdge 3) UAV images, I noticed the following issues.

1) On the first set of data (all images collected during the same flight mission), the alignment was initially good. But I noticed that after adding GCPs, a portion of the tie points on the left side appear disconnected from the rest of the surface (Image 1). This gives me totally off DEM values.

2) Ran a second set captured over the same area, on a different dat, and used the same set of GCPs. The tie points appear fine, expect the DEM shows abnormally low values at the bottom low corner (Image 2). Not all the markers that appear on the screenshot were used for correction. The markers with the 'point' prefix were added later to derive something else from the orthomosaic. Another issue with this DEM is the patchy surface on the right side, which has been encircled in Image 3. The actual surface doesn't look anything like this.

3) I have attached the DEM generated from Zenmuse 3 RGB camera for reference (Image 4). This is the closest reconstruction of the original surface. The same GCPs were used, and the markers with prefix 'point' were added later for a different purpose.

I appreciate any help or advice on this issue.