How do I clip my data down to a selected polygon or region boundary?

Discover provides a number of tools that allow you to clip or cut your datasets down to selected regions/areas. An example would be to provide subsetted datasets to government organisations for lease relinquishment reports, or to a joint venture partner.

The tools are data type specific, i.e. vector, image or grid data:


Vector Data

(i.e. point, polygon or polyline data, such as soil sample or drillhole point locations, surface geology regions, traverse lines and track polyline data)

Use the Discover>Object Editing>Clip to Polygon tool. This requires the user to select one or more bounding regions/polygons (e.g. the sub-blocks to be relinquished) before running the tool.



Raster Data (e.g. airphotos, landsat imagery)

The Images menu (Discover>Images menu) has a Clip Image tool. This provides 3 methods for defining the clip region/area:

    1. Select one or more  bounding regions/polygons (e.g. the sub-blocks to be relinquished) before running the tool. Within the tool, enable the 'Clip outside polygon' option, and ensure that the 'Table *Selection*' is enabled (below).



   2. Within the tool, select the table containing the polygonal areas to clip the image to. All polygons in the specified table will be utilised (below).



    3. Within the tool, freehand draw a rough bounding polygon in the preview screen by enabling the 'Custom rectangle' option




Gridded Surfaces

(e.g. DEM or topographic, geophysical (IP, magnetics) or geochemical (copper in soil sampling) grids)

Either select one or more polygons to clip with, or ensure that a table with the delimiting regions is open in the mapper with the target grid surface.

From the Surfaces menu (Discover>Surfaces menu), select Grid Utilities>Clip. Choose either the *Selection* option (if one or more polygons are selected) or the table containing the polygons (example below):



Within the dialog, ensure that the options below are selected: the preview of the output will be displayed. Press Save As to create the clipped grid.


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Last Updated on: 18th of May, 2011