Selection Polygon

Use the SEM-Data > Selection Polygon option (SEMSELECTPOLY GX) to select data inside a polygon in an existing map.

Selection Polygon dialog options

Mask channel

The "Mask" channel records whether a row of data is selected or not. A dummy is used to indicate that the data is NOT selected, while a 1 indicates the data is selected. (In fact any non-dummy value will be interpreted as "selected"). Any channel can be used as a Mask channel, but only those channels whose CLASS is set to MASK are included in the list. Multiple mask channels can be used to record the results of different filters or selections. The latest mask channel specified in any of the filter/selection options is used when creating plots.

Script Parameter: SEMPLOT.MASK

Selection mode

New Add points within the selected area to the selection, and remove all points outside the area from the selection. Append Add points within the selected area to the selection. Remove Remove points within the selected area from the selection.

Script Parameter: SEMSELECTPOLY.MODE 

Application Notes

If the "Enforce Mineral ID on plots" setting is set to No, then all of the mask channel values will be processed, not just those of the mineral for the chosen plot. By default, this setting is Yes, so if the plot uses only Chromite values (for example) then only those rows of data with "C" for the mineral will be altered using this GX.