I need some help from anybody that does work in southern Virginia. I set up a project in Bristol Va and NAD83(20011) Virginia South Zone as the coordinate system. I DPOS the base and do my shots. I look at the FEMA map for flood elevation at the site and my shots are 100' lower than the FEMA map is showing. What am I missing in my setup that anybody could guide me?
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FEMA elevations
- Thread starter Michael
- Start date
Michael, I don't work in your area, but just a guess, maybe either no Geoid model loaded with your projection , or a incorrect model loaded? Try geoid18_conus.I need some help from anybody that does work in southern Virginia. I set up a project in Bristol Va and NAD83(20011) Virginia South Zone as the coordinate system. I DPOS the base and do my shots. I look at the FEMA map for flood elevation at the site and my shots are 100' lower than the FEMA map is showing. What am I missing in my setup that anybody could guide me?
Greg Flowe
Active Member
Steve is correct on this. Sounds like missing GeoidMichael, I don't work in your area, but just a guess, maybe either no Geoid model loaded with your projection , or a incorrect model loaded? Try geoid18_conus.
Steve and Greg, I think you are right I checked the underlying coord and it seems it was only SPC VA South with no NAV88. We do not do much in VA and have not done any elevation work at all. I checked our TN jobs and I had it NAV 88 and TN SPC. We will check base point with new underlying geoid 18_conus. Now I will be able get a good night rest. You guys are the best. Thank you.