Filter Boundary Tool

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Posts: 19
Joined: Thu Jan 01, 1970 00:00

Filter Boundary Tool

Postby » Tue Jul 20, 2004 10:28

Hello Folks,

A small note about Filter Boundary Tool (in Mohid GIS tool menu).


Sometimes boundary definition is too refined and you might need to coarsen it in order to generate a mesh or interpolate bathimetry.
Filter Boundary tool is a filter that averages the boundary line. It preforms nothing but a moving average on the line coordinates so small perturbations are eliminated. This average is weighted accordingly to the distances from the central point of the moving average.


Select 'Tools->Filter Boundary...'
Now you select the polygon-that is, your boundary-you need to coarsen, give the values for the parameters and then click on 'Add Modified'.
Here, a description of the parameters:

i) Boundary definition (D) : all segments smaller than this length are removed from the polygon.
ii) Average order (N) : perform moving average over the number of points given here. The average distance between N consecutive points should be about D. Bellow a figure that illustrates an average order of 5.
iii) Central weigth (W) : in the average process a higher weight can be given to the central point of the moving average. As a result, he resulting filtered boundary will stick closer to the original contour line. This weight ranges from 0 to 1. If W = 1, the resulting polygon will follow exactly the boundary line. A recommended value is 1 / N.


Any complain on this should be addressed to me.
Now go to work.

Posts: 46
Joined: Thu Jan 01, 1970 00:00

Postby CampuzanoFJ » Mon Nov 16, 2009 11:53

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