What does a PLS that does not use RTK do for Item A5 on the Elevation Certificate? FEMA says show value to nearest 10th of a second (and accurate within 66 feet).
Can a surveyor provide an elevation certificate without providing this info. The form does let us check "No", in Section D.
Pick the lat & long off Google Earth and note your source where it asks.
This is perfectly acceptable.
Scott
I would use a hand held GPS at the site and go with it. I've checked the autonomous RTK position against the post processed for years and usually find it within 10 feet. You could always just note in the comments how you got the number. My gut tells me this isn't checked very closely anyway.
I have rtk that I use for lat/long on the elevation certificates.
After I put the numbers in the ec, I check them with Google Earth...Usually it appears to be correct within a couple of feet--at least in my area.
I'm actually surprised/amazed how tight it is.
waas enabled handheld will get you want thay want.
I use my hand held or the Garmin on the truck dash and compare to Google Earth. All three land within 40 feet.
Yes, this is acceptable to FEMA. Once submitted an e-LOMA with a typo on the Lat/Long and they sent me an email to tell me they corrected it and listed their source as ARC MAP 10. I was surprised they were paying that close attention.
Scott
What point are you supposed to give coordinates for? Front door? Driveway? Center of house? Center of lot? With 66 ft tolerance it isn't a big deal, but it would be nice to know what point it is.
A bit off the subject, but relating to the accuracy of the rectification of Google Earth imagery, at least in this particular case...
I was in west Tennessee a couple of weeks ago for a GPS seminar. We had a network rover with us and sort of on a lark, I decided to do a search on line for local monuments that we might check in on with the network rover.
I found one that promised to still be intact, being that it was in the top of a headwall at a major intersection in the town we were in.
When I went to Google Earth and typed in the lat/long and hit enter, it drilled down to precisely the end of the headwall, clearly visible in the image and exactly where the monument was described to be. When we went to locate it the next morning, it hit exactly where the Google Earth image showed it to be and check with the published position within 0.02-0.03 feet.
Maybe just me, but I thought that was pretty cool.
Bill, the instructions say "the center of the front of the building".
A consumer-grade WAAS-corrected handheld GPS should be accurate within about +/- 5 meters with reasonable view of the sky.
Typically the most precise positional output might be obtained with decimal degrees to five decimal places. 0.00001 degree is equivalent to 0.036" which is inside your accuracy requirement.