Polyline - Nearest point

[PaulHedlund]

How do I find the location on a polyline that is closest to another point on the map.  For a visual of what I am looking for, in the attached PolylinePoint.png I want to obtain the yellow "Nearest Point' location.

The geometry task 'DistanceAsync' gets the closest distance between a polyline and point.  However, I am looking for that 'Nearest Point' location.

[wangzhifang]

This can be done easily by client side.
Just use dist=Math.Square(a*a+b*b) to calculate every distance between your point and each point on the polyline, then you get the nearest point on the polyline.

[PaulHedlund]

The problem is I am looking for the nearest location on the polyline.  The location may not contain a vertex. (see attached visual)

Looping through each vertice and using your forumla would give me the distance from each vertice.  But, that is not what I am looking for.

The 'DistanceAsync' task gives me the distance, but for some reason I can't get the polyline nearest location.  I would think the value for this would be exposed somewhere.

[Sravan_KumarUddarraju]

I am looking for the samething. I need to find nearest point on the segment.
Were you able to find the solution for this?

Srav

[SimoLukic]

Maybe convert the polyline into a List of Points.
If you have a line  between x1 and x5, cut it in pieces and check for distence with x2,x3,x4.

[DominiqueBroux]

If the segment is a straight line (i.e. not an arc, ellipse, ...), it looks easy:
    - project the point on the line,
    - if the projected point is on the segment => it's the shortest distance
    - if not on the segment, thye shortest distance is given by the closest vertex.

[CostasKotzabassis]

Hello Dominique,
I found your response intriguing, but I cannot quite follow.
How do you project a point to a line segment using Silverlight API 3.1?

[DominiqueBroux]

Hello Dominique,
I found your response intriguing, but I cannot quite follow.
How do you project a point to a line segment using Silverlight API 3.1?

I put together a Geometry Projection sample.