GRD is the file extension for Arc/Info ASCII Grid files. Arc/Info is a popular, commercial GIS (geographic information system) package from ESRI Corp., and Arc/Info ASCII Grid refers to the specific non-proprietary format developed for Arc/Info, which was specifically built to be used as an exchange or export format.
The GRD file format consists of a header that gives the geographic domain and resolution, followed by grid cell values. The header has six lines, called records – the first has ncols xxxxx (ncols refers to the number of columns in the grid and the xxxxx is the numerical value; the second has nrows xxxxx (where nrows is the number of rows and xxxxx is the numerical value); the third has xllcorner xxxxx (with xllcorner being the western edge of the grid and the xxxxx is the numerical value; the fourth is yllcorner xxxxx (where yllcorner refers to the southern edge of the grid and xxxxx is the numerical value; the fifth is cellsize xxxxx (where cellsize is the resolution of the grid and xxxxx is the numerical value); and the sixth and final record is NODATA_value xxxxx (NODATA_value being the value that represents the missing data and xxxxx is the numerical value). If no data is missing, then the final record is ignored.
The actual grid cell values follow the header. These values, which are generally stored as integers but can also be read as floating point values, represent geographic attributes, such as elevation, surface slope, and so on.
All GRD files are 16 bit single layered files and are read in Arc/Info with the ASCII Grid command. Convert GRD files to TIFF, JPEG, PDF, BMP, PNG with Total GIS Converter.
- Convert GIS files in batch
- GRD to PNG, TIFF, JPEG, BMP
- Combine into one file