User Manual - pancroma

63. Writing an Index File for an SRTM DTED1 DEM Image________________________________________________________________Sometimes it is necessary to produce a formatted array of elevation data for adigital elevation model. That is, an ASCII file that lists the X and Y coordinates ofthe bitmap image, the latitude and longitude, and the elevation of eachcorresponding point. PANCROMA TM has a utility for creating such a file fromSRTM DTED DEM images. These DEM images cover one degree of latitudeand longitude for virtually the entire surface of the earth and are available for freefrom the USGS Earth Explorer site at http://edcsns17.cr.usgs.gov/EarthExplorer/.Although SRTM DEM data is available in several formats, the DTED tiles areconvenient because they are of fixed and manageable size. These files cancurrently be downloaded by selecting your area of interest using the rubber bandbox using the Earth Explorer interfaceWhen you select ‘Search’ a list of DEM tiles, each containing either 1201 by 1201postings (DTED1) or 3601 by 3601 postings (DTED2) will be listed.298