Direction to nearest point of a polygon

[ckgoo...@gmail.com]

Hi, I have a point and a polygon.  The point is outside of the polygon.  I can use ST_Distance to get a distance from the point to the nearest part of the polygon.  This is good.  Is there a way to find the direction from the point to the nearest point on the polygon?

 

I have looked at Azimuth but this expects two point geometries.

I have looked at InterpolatePoint but this expects a line geometry.

I tried CastToLinestring  on my polygon but it looks like I still get a null response.

And this is where I am stuck.

 

My only other thought is to do a little algorithm where I first find the distance between the point and the polygon.  Say I get 5000m as the result.  I could then make a circle of points around my original point of radius 1000m testing the distance for each.  I find the point with the minimum distance.  This point and my original point will then point towards the nearest point of the polygon and I can use the Azimuth function.

But I hope there is a simpler way.

 

Best,

Chris

[Jukka Rahkonen]

Hi,

Have you tried ClosestPoint https://www.gaia-gis.it/gaia-sins/spatialite-sql-5.1.0.html to start with?

-Jukka Rahkonen-

[ckgoo...@gmail.com]

Hi Jukka,

Thanks.  I didn’t see that one.  Looks just the thing I needed.

Many thanks, Chris

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