performance specification digital terrain elevation data

MIL-PRF-89020Bf. Data Record Description. The Data Record is used for magnetic tapeand CD-ROM.Each elevation is a true value as determined by the Earth GravityModel (EGM) 1996 recorded to the nearest meter. The horizontal position isreferenced to precise longitude-latitude locations in terms of the currentWorld Geodetic System (WGS), determined for each file by reference to theorigin at the southwest corner. The elevations are evenly spaced inlatitude and longitude at the interval designated in the user header labelin South to North profile sequence.Field LengthField Contents In Bytes Description252 8 1 Recognition Sentinel.Data block count 3 Sequential count of the block withinthe file, starting with zero for thefirst block (Fixed Binary).Longitude count 2 Count of the meridian. Truelongitude = longitude count x datainterval + origin (Offset from theSW corner longitude) (Fixed Binary).Latitude count 2 Count of the parallel. Truelatitude = latitude count x datainterval + origin (Offset from theSW corner latitude) (Fixed Binary).Elevation 1 2 True elevation value of point 1 ofmeridian in meters (Fixed Binary).Elevation 2 2 True elevation value of point 2of meridian in meters (FixedBinary).Elevation N 2 True elevation value of point N ofmeridian in meters (Fixed Binary).Checksum 4 Algebraic addition of contents ofblock. Sum is computed as aninteger summation of 8-bit values(Fixed Binary).Note: Fixed Binary denotes signed magnitude, right-justified binary integers.g. File Trailer Label (EOF). The EOF is used for magnetic tape.Field LengthField Contents In Characters DescriptionEOF 3 Recognition Sentinel.1 1 Fixed by standard.Note: (See HDR for remainder of EOF fields.)30