The Surfer Grid (.GRD) Interpolation Output format (or Map Input format) has a short header area that provides information needed for mapping, and the data is then written as a continuous stream of Z-estimates beginning from a specific corner of the interpolation grid. The standard deviation of the estimate and the number of neighbors used for interpolation are not included in this format. This format is compatible with Golden SoftwareSurfer™ mapping program. Note that the Surfer Grid format is different from the Surfer XYZ Input File format.
The following listing is for the first 100 or so coordinates in a standard Surfer Grid format file. The first record is a required line of code letters that identifies the file as a Surfer grid file. Record two contains the number of grid lines along the x axis and y axis, respectively. Record 3 contains the minimum and maximum values of the x-coordinate. Record 4 contains the minimum and maximum values of the y coordinate. Record 4 contains the minimum and maximum values for the z-variate. Records 5+ contain the z values organized in row order. Within each row the y-coordinate is constant, and the grid row 1 corresponds to the lowest y-coordinate value and the last row corresponds to the highest y-coordinate. Within each row the z-variate values are ordered from low x-coordinate to highest x-coordinate.
DSAA
376 253
-185556.375 194194.225
-127261.523 128262.152
81.000 4469.000
578 746 1097 1251 581 312 229 229 235 278 292 357 490 997 1411 1397 1373 1373 1370 1061 942 1003 1288 1014 785 963 934 797 703 924 1035 1071 1257 1775 1800 1520 1460 1520 1278 1098 915 645 495 450 378 339 342 425 613 1084 1292 1701 1682 1996 2280 2107 1662 1553 1418 1162 1225 1266 1735 1674 1550 1800 2015 2240 2158 2328 2262 2173 2046 1688 1849 1880 2023 2320 2029 2140 2240 2650 2465 2369 2180