Island Size Filtering

This reduces detail by removing Polygons and Polylines whose width and height is smaller than the supplied distance.

This type of filtering will work in all cases. Islands which cross tile boundaries are ignored, as are those that are made up of more that one primitive.

Can be used in conjunction with Line Simplification, Angle Change or Line Delta Filtering, or on its own.

Parameters:

Minimum diameter. Value entered in Map Units.

Operations:

Removes all Polygons and Polylines whose diameter is less than Minimum diameter, unless one of the points in the primitive is shared between more than 2 Polygons, in which case the whole primitive is left. This rule prevents white space appearing in the gap left by the island.

To apply Island Size Filtering to a Layer:

• Select Layer | Filtering... to bring up the Filtering page
• Select the Island Filter Apply checkbox
• Then supply a value for the Minimum Diameter using one of the following methods:
• Enter a value directly into the edit box
• Press Evaluate to scan the currently loaded layer and suggest values for Minimum Diameter. Then press Transfer to transfer the suggested values into the parameter boxes
• Press Suggest to evaluate to evaluate a value and Transfer it to the parameter box in one operation
• Press OK to accept the changes