Turf booleanPointInPolygon always returns false

Question

I want to check if a point is in a polygon:

if (turf.booleanPointInPolygon(pt, poly_coordinates)) {
    console.log("INSIDE");
} else {
    console.log("OUTSIDE");
}

JSON.stringify(console.log(pt)) displays:

{"type":"Feature","properties":{},"geometry":{"type":"Point","coordinates":[2.1362996,41.391026000000004]}}

JSON.stringify(console.log(poly_coordinates)) displays:

[[[2.1666008868967594,41.420742231455876],[2.1423966327457435,41.39486355482066],[2.159906093195218,41.38185595077573],[2.1666008868967594,41.420742231455876]]]

NOTE: Everything is in longitude,latitude format.

Why is it booleanPointInPolygon returning false? This particular case is just an example point and an example polygon which might be outside the polygon. However, it doesn't matter if the polygon contains the entire world, booleanPointInPolygon still returns false for any point.

It'll be much easier to diagnose if you include example data. — Steve Bennett, Apr 25 '20 at 15:04
@SteveBennett I added the JSON for the list of points (ranked_racks) and another for the output of a drawn polygon (zone). Thanks! — fbu_94, Apr 26 '20 at 10:16
@SteveBennett I simplified the question for clarity. Hopefully, everything is more clear now. — fbu_94, Apr 26 '20 at 10:37

score 2 · Accepted Answer · answered Apr 26 '20 at 11:57

2

If that's your code, then the problem is that poly_coordinates is not a polygon, it's just the coordinates part of one.

You should have something like:

const poly = { type: 'Polygon', coordinates: poly_coordinates }
turf.booleanPointInPolygon(pt, poly)

answered Apr 26 '20 at 11:57

Steve Bennett

114,604
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168
219

That solved it. Nevertheless, I want to understand why my attempt did not work. My coordinates for the polygon have exactly the same format as the example in the [documentation](https://www.npmjs.com/package/@turf/boolean-point-in-polygon) of `booleanPointInPolygon`. – fbu_94 Apr 26 '20 at 16:11
In that example, the array is first being passed to `turf.polygon()` which does the same thing as I added. – Steve Bennett Apr 26 '20 at 16:41

score 2 · Answer 2 · answered Jul 28 '23 at 12:55

2

Hi you can also use this

var pt = turf.point([1, 1]);
var poly = turf.polygon([
    [
        [-1, -1],
        [-1, 1],
        [1, 1],
        [-1, -1]
    ]
]);

var inside = turf.pointsWithinPolygon(pt, poly);

answered Jul 28 '23 at 12:55

Robert S

626
6
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Turf booleanPointInPolygon always returns false

2 Answers2

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