trailbiscuit said:
I knew that DougPaul would be on the case!
All I did was look at an NG TOPO! map or two... My comments are no better than the info contained within.
RoySwkr said:
The 7.5' map says 4228
The old 15' map said 4168
Good point. I was looking at the 7.5' map.
If I look at the 15' (1:100K scale) map, it says 1270m which is equal to 4167 ft.
If the DEM value (4118 ft) is from the Shuttle Radar Topography Mission (SRTM,
http://srtm.usgs.gov/ http://en.wikipedia.org/wiki/SRTM) then that would be an independent measurement more consistent with 4228 than 4168 ft.
The maps referred to above are all NG TOPO Northeastern USA v 2.7.5. I think, but have not established that the DEM is indeed from SRTM data. (The box simply says "High resolution 30-meter digital elevation data".) If DEM is from SRTM data, then it is an independent measurement. DEMs can also be derived from topos, if so it would not be an independent measurement.
Just to stir the pot a little more, I looked at my Garmin maps:
* US Topo 2008 (100K) label: 4222 ft**
* US Topo 2008 (100K) contours: >4200 ft, < 4225 ft
* US Topo 2008 (100K) DEM: 4212 ft (manual search for highest point)
* US Topo 24K, National Parks East label: 4168 ft.
* US Topo 24K, National Parks East contours: >4200 ft, <4220ft
** I'm guessing that this is a typo for 4228.
(Garmin gives no info on their DEM data.)
To summarize the NG TOPO! numbers:
* NG TOPO! 100K label: 4168 ft.
* NG TOPO! 100K contours: >1260m (4134 ft), <1280m (4199 ft)
* NG TOPO! 7.5' (24K) label: 4228 ft
* NG TOPO! 7.5' (24K) contour: >4220 ft, <4240 ft contours
* NG TOPO! 30m DEM: 4218 ft (manual search for highest point)
(30m DEM data.)
The 100K and 7.5' (24K) data all come from the same original map data (USGS 100K and USGS 24K) and it looks like the same DEM data was used in both products too.
Anyhow I'm out of maps.
Your choice which you choose to believe...
Doug
