4
votes
3answers
183 views

Does the NED use geocentric or geodetic latitude?

What kind of latitude does the National Elevation Dataset (NED) use? Geocentric or geodetic or something else? I can't find the information anywhere on their site (http://ned.usgs.gov/index.html) or ...
11
votes
2answers
6k views

How do you compute the earth's radius at a given geodetic latitude?

(I see there is an equation on wikipedia that does exactly what I am asking but there is no references. I have no way of confirming the validity of this equation!) I already understand the difference ...
12
votes
2answers
593 views

How do you find a lat/lon (DMS) on a paper map using a 30cm ruler?

How do you use a 30cm ruler to find DMS on a paper map? The locations I would like to find are the 'corner' points so I can generate an extent based on the four corners. I have an old paper map (3 ...