NoData Definition

In Surfer 16, the term "blanking" has been replaced by "assign the NoData value to." The term "blank value"  has been replaced by "NoData value". The terms "blanking" and "blank value" were used in previous Surfer versions.


Assigning the NoData value is the process of removing grid node data from a grid file. The NoData value, a special code (1.70141e+38), is assigned to grid nodes. NoData regions of a grid file are not displayed by default, e.g. NoData values do not display contour lines on a contour map. On a 3D wireframe or 3D surface, NoData regions are represented by low flat regions. Most map types include options for displaying NoData values in the Properties window General page.


The grid node value must be exactly equal to the NoData value (1.70141e+38 by default) to be considered a NoData grid node. Grid nodes with values close to, but not exactly matching, the NoData value will often result in undesired maps: contour maps with no contour lines, single-color color relief maps, etc.