Help needed: straight-line distance to Coast from a point on island

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Aug 5, 2022, 12:15:54 AM8/5/22

to SpatiaLite Users

The island is a polygon, and the point is inside the polygon.

Need to calculate the straight-line distance

I can think of a way:

step 1. Get closest point :

select ST_ClosestPoint(ST_Boundary(SetSRID(geometry, 26917)), srctable.srcpt) as ptNearest

step 2. Get the distance:

Math.Sqrt(Math.Pow(ptSrc.X - ptNearest.X, 2) + Math.Pow(ptSrc.Y - ptNearest.Y, 2));

Is there a better way?

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Aug 5, 2022, 12:41:18 AM8/5/22

to SpatiaLite Users

Yes.

Again, study the Cookbook (Version 5.0.0):

SpatiaLite Cookbook Topics

The answer you are looking for is contained in part 3 of recipe #17: Railways vs Populated Places

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