Yves is absolutely correct. Each pixel that is "no data" is a separate value.
On Mar 4, 2012, at 3:25 PM, yvecai wrote: > I think one pixel= one elevation value, and : > "File names refer to the latitude and longitude of the lower left corner of > the tile - e.g. N37W105 has its lower left corner at 37 degrees north > latitude and 105 degrees west longitude. To be more exact, these > coordinates refer to the geometric center of the lower left pixel, which in > the case of SRTM3 data will be about 90 meters in extent." > > All the doc is here: > http://dds.cr.usgs.gov/srtm/version2_1/Documentation/ > ;-) > Yves > > Le 04/03/2012 20:53, Mr. Puneet Kishor a écrit : >> On Mar 4, 2012, at 1:39 PM, Ed Linde wrote: >> >>> Thanks Yves, but my question still remains though. So in this raster of >>> 1200 x 1200 pixels, does each pixel get assigned an elevation in meters of >>> "x" meters? Or do the four corners of each pixel have different elevation >>> values of a,b,c and d meters each? >>> .. >> I am guessing (albeit, based on my fiddling with SRTM a long time ago) that >> it is an ave value of "x" meters assigned to all the pixels in the tile. In >> essence, a 1200 pixel-square tile is behaving like a single large pixel with >> a value of "x" meters. >> >> >> Should be easy to confirm it by querying a few random pixels in a tile. >> >> >> >> >> -- >> Puneet Kishor >> _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
