All Return Text File Data files containing information about each laser return consist of gzipped ascii text files. Each file consists of one fixed length record for each laser return.  There are no header records. The records each consist of 10 fields: Parameter                Field Width            Read As gps_week                      4           long integer gps_second_of_week           13           double precision float easting                      11           double precision float northing                     11           double precision float orthometric_elevation         9           double precision float number_of_returns             2           integer return_number                 2           integer angle_off_nadir               7           float intensity                     6           long integer classification                2           character An example of a data record is: 1205 174436.50828 6151368.67 2011080.93     3.14 1 5  16.64    43 G GPS_week and GPS_second_of_week refer to the time of the laser pulse transmission. Easting, (in survey feet), northing (in survey feet), and orthometric_elevation (in international feet) refer to the location of the return. Up to four returns can be recorded per laser pulse; number_of_returns is the total returns for a pulse (up to a maximum of 4). Return_number is assigned as a number from 1 to 7 in a scheme that identifies which return is the last return recorded for a pulse: 1 first return with subsequent returns detected 2 second return with subsequent returns detected 3 third return with subsequent returns detected 4 fourth return 5 first return with no subsequent returns detected 6 second return with no subsequent returns detected 7 third return with no subsequent returns detected Angle_off_nadir refers to the orientation of the laser pulse vector, combining scan mirror and aircraft orientations. Intensity is an uncalibrated measure of received energy for the return. Classification of each return was implemented by TerraPoint using the TerraScan software developed by TerraSolid.  Returns are classified as: B Blunder; anomalous return above or below return point cloud G Ground or water; the "bald Earth" surface V Vegetation S Building/Structure