Spent 3 hours trying to sync a laser level with a drone survey last Thursday

I was working on a commercial foundation layout in Phoenix where the site plans had this weird angle offset. The drone guy gave me a point cloud file, and my laser level kept giving me readings that were 2 inches off. Took me forever to realize the drone's coordinate system was set to a different datum than my total station. Has anyone else run into this mismatch between aerial survey data and ground tools?

3 comments

3 Comments

robert_rodriguez6627d agoTop Commenter

Get the drone guy to export his data in State Plane coordinates instead of WGS84. It's that simple. I had the exact same problem on a job in Tempe last month. Two inches off because the drone was using a different coordinate system than my old Trimble. Once I made him switch to NAD83 in Arizona Central, everything lined up perfect. Tell him to check his processing software settings before you burn any more time. Most of them default to WGS84 because it works for their mapping apps but it's useless for construction layout.

benlewis27d ago

Wait, did your drone guy give you any pushback on that? I ask because my buddy Mike had this exact fight on a site in Phoenix last year. His surveyor was pulling his hair out because the drone point cloud was two inches low on every check shot. The drone guy kept insisting it was a GPS issue and tried to blame Mike's old prism pole. Mike finally drove to the guys office, sat down at his laptop, and made him switch the export from WGS84 to NAD83 Arizona East right in front of him. Everything clicked into place after that. Two inches of pure headache over a dropdown menu in some processing software.

samthompson27d ago

Yeah I've hit that exact 2 inch ghost before. The drone data and ground tools almost never play nice out of the box. What finally fixed it for me was forcing the drone guy to dump his point cloud in the same state plane zone and datum as my total station, not the default WGS84 they all seem to use.