Finding intersection points of two polyline features using ArcObjects?

Question

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;
        sc.AddSegment((ISegment)poly2);

        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.

Answer 1

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++)
        {
            resultPoints.Add((IPoint)pointCollection.get_Geometry(i));
        }

Answer 2

Use ITopologicalOperator instead. See ITopologicalOperator.Intersect method.