Using Arc Desktop 10.5.1, I have been tasked with mosaicking two adjacent LiDAR rasters (I'll call them A and B). They were flown, processed and supplied under contract by different vendors, A in 2013 and B in 2015.
Each raster was accompanied by a detailed project report, signed off by a professional land surveyor. Both projects used surveyed, GPS ground control points. Reported accuracy and RMSE values are all less than 0.1 feet.
Both rasters were supplied to me in the same CRS, with identical cell sizes (three feet), both single band, 32-bit floating point. To ensure that both rasters align, I snapped B to A .
A and B share a common boundary. They overlap along that boundary, with the overlapping width varying between ~ 300 - 600 feet.
I expected the elevation values between the two projects to be very similar. However, where they overlap, the cell values for A and B differ, ranging from -96 to +57 feet (!)
Please allow me to restate this: If I select a point within the overlap zone, the reported elevation values for A and B may differ by as much as 96 feet.
How is this huge range (153') in elevation values between the two rasters possible when so much professional attention was given to each of the two projects?