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Correcting Positioning for LiDAR Datatset

Question asked by gaspiras01 on Apr 27, 2020
Latest reply on May 1, 2020 by pbecker-esristaff

I am analyzing multiple LiDAR datasets looking at the changes between pre-wildfire and post-wildfire topography. The datatsets are of the same general location. I did not acquire the datasets on my own, so I am not the one who originally reduced the raw data from the instrument, which is part of my issue as I was not the individual to verify horizontal control.

 

The problem that I am having is that the datasets are, in general, slightly offset from one another. This poses a major problem for generating a comparison (raster subtraction) looking at elevation change. When I process such a comparison, the offset is more apparent on south facing slopes because they are steeper. I have included an illustration of my issue below. As is evident, the south facing slopes show a characteristic false positive change in elevation and the north facing slopes show a characteristic false negative change in elevation, though it is less drastic because the north facing slopes are not as steep.

 

I am hopeful that someone with experience can shed some light on a possible solution to this issue. Of course, the datasets can be shifted using the georeferencing toolbar, but I would just be guessing at the correct shift. I am looking for a systematic way of handling the shift. Possibly finding the corner of some landmark and using that point to align the datasets.LiDAR

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