Hi,

I am trying to build adjacency matrices for the features in a vector layer by testing the interconnections between the respective features. I have experienced some problems in using "MapWinGIS.SelectMode.INTERSECTION".

Basically I am using the following code;

Public Module MyExample
Public Sub ScriptMain(ByRef m_MapWin As IMapWin)

Dim sh as new MapWinGIS.shapefile
Dim handle As Long
dim s1 as new MapWinGIS.shape
Dim ArrayShpCount As Integer = 0
Dim ArrayShp(ArrayShpCount) As Integer

sh = CType(m_MapWin.Layers(handle).GetObject, MapWinGIS.Shapefile)
s1 = sh.shape(0)
sh.SelectShapes(s1.Extents, 0.0, MapWinGIS.SelectMode.INTERSECTION, ArrayShp)

End Sub
End Module

The resulting Arrayshp does not include some IDs of the feature that actually intersect with the selected feature (s1). I attached a sample file to this message. If you try to select the features that intersect with s1 (ID=0) by using MapWinGIS.SelectMode.INTERSECTION, it could find any intersection between ID=0 and ID=4 features even through the respective features actually intersect each other.

I think some modifications are needed in the respective part of MapWindow GIS package to solve the problem associated with MapWinGIS.SelectMode.INTERSECTION.

Kind regards,


Burak

You can increase the tolerance to search in a more wider area around your shape.
Do remember the shapes have an internal ID which don't need to be the same as your ID.
sf.SelectShapes() returns True is it finds one or more shapes.
Here's some documentation: [www.mapwindow.org]

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When I increase the tolerance to search in a more wider area, features previously not selected can be selected. Nevertheless, those features which do not actually intersect with sı (ID=0) are also included in the resulting ArrayShp (I did not sent the original file that involves a large network of lines).

By the way I am checking the intersection through internal ID of the features by employing the following code for each feature ID included in ArrayShp;

for j = 0 to ArrayShp.Length - 1
mapwinutility.logger.msg("Testing Intersection: " & ArrayShp(j))
next j

for the first 4 features (0, 1, 2, 3) the result corresponds to the internal ID. But beginning from the 4th feature the correspondence between IDs is disturbed, signalling the failure in detection of the intersection between feature ID = 0 and feature ID = 4.

Best regards,


Burak