topic Re: Finding intersection point of two lines on "extending the lines" till they inters in ArcObjects SDK Questions

Finding intersection point of two lines on "extending the lines" till they intersect

VivekPrasad — Tue, 22 Apr 2014 05:41:14 GMT

Hi All,

Could any one please direct me on finding an intersection point of two polyline objects by extending them till they intersect, using ArcObjects (its not 3D). The two input polylines initially do not intersect. Need to identify the point where they intersect when their ToPoint 's are extended.

Thanks in advance!

With Regards,
Vara Prasad.

Re: Finding intersection point of two lines on "extending the lines" till they inters

WeifengHe — Tue, 22 Apr 2014 15:51:42 GMT

I think there are some existing ArcObjects methods might be useful to you.

IConstructCurve.ConstructExtended
http://resources.arcgis.com/en/help/arcobjects-net/componenthelp/index.html#//002m000000t6000000

IConstructLine.ConstructExtended
http://resources.arcgis.com/en/help/arcobjects-net/componenthelp/index.html#/ConstructExtended_Method/002m000000v9000000/

Re: Finding intersection point of two lines on "extending the lines" till they inters

AhmedEl-Sisi — Sun, 12 Dec 2021 01:34:21 GMT

Based on This Post you can get the approximate intersection point of two lines.

 
        public IPoint GetLinesIntersection(IPoint line1P1, IPoint line1P2, IPoint line2P1, IPoint line2P2)
        {
            //Line 1 (p1, p2)
            var A1 = line1P2.Y - line1P1.Y;
            var B1 = line1P1.X - line1P2.X;
            var C1 = A1 * line1P1.X + B1 * line1P1.Y;

            //Line 2 (p3,  p4)
            var A2 = line2P2.Y - line2P1.Y;
            var B2 = line2P1.X - line2P2.X;
            var C2 = A2 * line2P1.X + B2 * line2P1.Y;

            var determinate = A1 * B2 - A2 * B1;

            IPoint intersectionPoint;
            if (determinate != 0)
            {
                double  x = (B2 * C1 - B1 * C2) / determinate;
                double  y = (A1 * C2 - A2 * C1) / determinate;
                intersectionPoint = new Point();
                intersectionPoint.X = x;
                intersectionPoint.Y = y;
            }
            else //lines are parrallel
                intersectionPoint = null;

            return intersectionPoint;
        }

Regards,