[postgis-users] Closest points to positions along a line

[Thurber, Fred]

I am a newbie to PostGIS and have a spatial question.

We have a geographical straight line with equidistant positions along the line.  We need to find the closest point for each position on the line.

I suppose that the obvious way to do this is to solve the closest point problem for each position on the line, but I cannot find an easy way to do this in PostGIS. I could "ORDER BY distance" and limit the results to 1.  To prevent a full table search I suppose I could limit the search to an overlapping BOX2D (if there are no matches, I could use the expand function on the box until I find a match).  Is there a better way to do this?

Is there a way to solve this problem in one step?  I am tempted to draw a box around the whole line and return all the points in a subquery then do the distance queries on that result, but I am not sure I can do such a query in SQL.


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