Angle Change Filtering

This reduces detail by removing points between segments if the angle between the segments is less than the defined value. This makes the Angle Change filter more advanced than the Line Delta filtering as this method takes into account the straightness of a line. Points in a line are more likely to be rejected than those in a curve.

Cannot be used in conjunction with Line Simplification or Line Delta Filtering, but can be used with Island Size Filtering

Parameters:

Interline Angle and Angle Sum. Values are entered in degrees.

Operation

Removes points at segment intersections if the angle between the segments is less than Interline Angle, unless the sum of all inter-segment angles between this point and the last not-removed point is greater than Angle Sum, in which case the point is kept. The Angle Sum therefore ensures that all points are not removed.

To apply Angle Change Filtering to a Layer:

• Select Layer | Filtering... to bring up the Filtering page
• Select the Angle Change Filter Apply checkbox
• Supply values for Interline Angle and Angle Sum 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 Interline Angle and Angle Sum. Press Transfer to transfer the suggested values into the parameter boxes
• Press Suggest to evaluate a value and Transfer it to the parameter box in one operation
• Press OK to accept the changes