Get the latitude longitude for a point on a shape (path)

Question

I have a a list of points (latitude,longitude), it's a bus path and around this path I have some points (bus stops), the points are not on the path.

I need to project the bus stops points on the path for compute the traveled distance from the beginning of the path for each bus stops. For that I need the know the latitude and longitude for each stops on the path.

I can compute the distance but I can't project the points on the path en get the new latitude-longitude of the bus stops points.

I search for a formula they do that without success...

Someone have an idea, I work with C# 4.0.

[What have you tried?](http://mattgemmell.com/2008/12/08/what-have-you-tried/) — Chuck Savage, Jul 16 '12 at 03:11
For each stops I have try to find his closest point on the shape but It's not accurate. — Maxime, Jul 16 '12 at 03:13
What are these points not on the path? X,y into a bitmap or something? — Peter Ritchie, Sep 24 '14 at 16:31

score 1 · Accepted Answer · answered Sep 24 '14 at 16:21

1

PostGIS has a function called ST_LineLocatePoint from which you can get an exact point using ST_LineInterpolatePoint.

The PostGIS source code is available here

answered Sep 24 '14 at 16:21

raphael

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score 0 · Answer 2 · answered Jul 16 '12 at 03:14

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I would say you need to calculate the minimum distance between the line (bus route) and the point (bus stop). See http://local.wasp.uwa.edu.au/~pbourke/geometry/pointline/

answered Jul 16 '12 at 03:14

Matt

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Thanks it's good start but I have difficulty to figure how I can get the latitude,longitude of the position on the path.. – Maxime Jul 16 '12 at 03:19

Get the latitude longitude for a point on a shape (path)

2 Answers2