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I'm currently working with street intersections trying to find point(or points) where 2 given streets intersect(!disjoin). Streets are all Polyline features, and I have to work with 2 features at given time. I think this way it can be determined if they intersect(haven't yet tested it),

    public List<IPoint> RoadIntersections(IPolyline poly1, IPolyline poly2)
        IRelationalOperator ro = null;
        ro = poly1 as IRelationalOperator;

        ISegmentCollection sc = new PolylineClass() as ISegmentCollection;

        if (ro.Disjoint(sc as IGeometry) == false) //if they intersect
            //TODO: find intersection points

but what I would like to do is to find point (or points) where those two polylines intersect.

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Have you tried using the "Locate Features Along Routes" tool in ArcGIS 10? – Aaron Aug 13 '12 at 15:19

2 Answers 2

up vote 5 down vote accepted

You can use ITopologicalOperator Interface for finding intersections. esriGeometry0Dimension gets you the result in points/multipoints.

        List<IPoint> resultPoints = new List<IPoint>();
        ITopologicalOperator topOperator = (ITopologicalOperator)poly1;
        IGeometry resultGeom = (IGeometry)topOperator.Intersect(poly2, esriGeometryDimension.esriGeometry0Dimension);

        IGeometryCollection pointCollection = (IGeometryCollection)resultGeom;

        for (int i = 0; i < pointCollection.GeometryCount; i++)
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Thanks, implemented in my code and it works. And I were actually starting to calcualte that point mathematically. :D – Sunder Aug 13 '12 at 11:45
thanks for the was typed from memory :) – vinayan Aug 13 '12 at 12:35

Use ITopologicalOperator instead. See ITopologicalOperator.Intersect method.

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