Have seen it too in California. It's not only the elevation also lat/lon is wrong for many summits. If there is any better source correct it. I verify it by gps and topo 24k and yahoo. If there is any official and better data I am all for replacing GNIS data.
On 9 Feb 2010, at 19:35 , Mike Thompson wrote: > It appears that there is a systematic error in the summit elevations > in OSM, at least in Colorado. For example, Longs Peak is listed in > OSM as having an elevation of 4340 meters (14,239 ft). The topo map > has it as 14,251 ft. I have noticed the same type of issue with > nearby peaks. I suspect this has to do with the GNIS import. The > elevations in the GNIS are from the National Elevation Dataset (NED), > not spot (e.g. summit) elevations. The NED gives the (presumably > average) elevation for a 3x3 arc second area. According to the > metadata for the GNIS: > > ====================== > Elevation figures are not official and do not represent precisely > measured or surveyed values. The data are extracted from the National > Elevation Dataset (<http://ned.usgs.gov/>) for the primary coordinates > and may differ from elevations cited in other sources. The differences > will be most evident for features such as summits where precision is > of more concern and where the local relief (rate of change of > elevation) may be more prominent. However, the elevation figures are > within tolerances for the data for most points and sufficiently > accurate for purposes of general information. > ====================== > > Precise and official elevations are very important for hikers and > mountineers, or at least we like to think they are. > > I believe that the National Geodetic Survey holds data on the official > elevations for summits within the U.S., but I need to look into that. > I am happy to start working on fixing this issue, but I didn't want to > commence if someone else is already working on. > > Mike > > _______________________________________________ > Talk-us mailing list > Talk-us@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-us _______________________________________________ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us