Window X ,Y to Polygon Mask

Use the Database Tools > Window Data > Window X ,Y to Polygon Mask menu option (WINXY GX) to mask the X and Y channels to the area defined by a polygonal mask file. This enables all map-based processing that follows to only use the data within the defined region.

Window X ,Y to Polygon Mask dialog options

Mask polygon file	Specify the ASCII file defining polygon masks. Script Parameter: WINXY.MASK
Dummy inside or outside	Indicate whether you want to dummy inside or outside of the polygon mask area. Script Parameter: WINXY.DUMMY

Application Notes

This GX is used to limit the X and Y coordinates to the part of the area to be plotted. All MAP based processes will use the X and Y channels as the plotting coordinates. By dummying those parts of the area outside the area of interest, all plotting will be restricted to the defined area.

A copy of the original X and Y channels are saved to channels "__X" and "__Y" (if they do not already exist). Subsequent windowing operations will use these channels as the source channels. (If running interactively, a warning message is displayed asking whether you wish to overwrite the backup channels).

Polygons are ASCII files with default extension .ply. A polygon file contains a list of X,Y coordinates that define one or more polygons. The file may contain any number of polygons, and each polygon may have any number of vertices. The first and last points in each polygon are assumed to connect. If the file will contain more than one polygon, each polygon must start with a line 'poly #' ('p' or 'P' in column 1). Comment lines are indicated by a '/' in column 1.

Clip polygon files may also be generated interactively by using the digitising tools in the Map Tools menu.

Example of a single polygon file: