The command line argument nv specifies whether zeros in the grid3 file are converted to NULL-values. Conversion is performed if the value is yes. The default is no.
The arguments type, precision, compression, and tiledimension are the standard g3d arguments which allow the user to overwrite the default properties of the new file. Note that the none value for compression only specifies that neither LZW nor RLE is used for compression. It does not turn off the compression all together. G3d does not support non-compressed files.
r3.in.grid3 uses float as default cell-type.
NOTE: Currently, after the file has been imported, the stored values are compared with the original data. This feature is used to find bugs in the library at an early stage and will be turned off as soon as confidence has built up.