Apply Mask to Data

Use the Apply Mask to Data option (CHPOLY GX) to create a mask channel based on a polygon or a rectangle mask file.

The option is available in the following menus:

Database Tools > Geostatistics Toolkit
Geochemistry : Geochem Analysis > Classify by Region

Apply Mask to Data dialog options

Mask file name	Polygon mask file to use Script Parameter: CHPOLY.FILE
Mask channel	Select the Mask Channel Name. The default mask channel is set from the CHPREFERENCES GX (Geochem Import/Preferences...). Script Parameter: CHPOLY.MASK
Work inside or outside area	Mask inside or outside of defined area. "Inside" means that if you have defined an inclusive mask, then the points outside the mask region will have their mask values set to dummy. "Outside" reverses this behaviour. Remember that at this time that one or more isolated exclusion polygons are NOT supported. All exclusion polygons must be contained within an inclusion polygon, or no points will be selected. Script Parameter: CHPOLY.AREA: ":INSIDE" or "OUTSIDE"
Append/New	Select to append to a Mask channel or create new Mask channel. "Append" means that values that are already selected ("") in the Mask channel will remain selected – these will not be reset to "dummy" even if the data is not found to be included in the current masking operation. All those values not excluded by the mask will have their mask channel values set to 1. "New" means that every value in the mask channel will be updated based on the current mask operation. Script Parameter: CHPOLY.APPEND (0:Append, 1:New)

Application Notes

The mask file is an ASCII file that lists all the points in a polygon that defines a region in to include or exclude data. The CHPOLY GX is used to apply the polygonal mask to the database, and creates a mask channel whose values are 1 or dummy, depending on whether the data is masked inside or outside the given area.