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I have the latitude and the longitude of view of map ( latitude and longitude of north west and the latitude and longitude of southeast ) and a geojson files with MultiPolygon. (43mo)

In PHP i want to detect if a polygon is in view.

test they 2 point (NW & SE) if is in polygons is not a good way because polygons is imprevisible https://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Rectangle_definition.svg/2000px-Rectangle_definition.svg.png in this case the result found is the corner NW and SE but the center and ne and sw not found

I need to know what are in view

example with this view: enter image description here I test NW and SE (of view) if is in polygon on center -> return false but i see the polygon on center

how i can know all polygons in actual view ?

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  • Your question is not totally clear. What does imprevisble mean? Commented Oct 18, 2015 at 15:14
  • like that zupimages.net/up/15/42/9jce.png Commented Oct 18, 2015 at 15:17
  • Imagine you are on webbrowser see that zupimages.net/up/15/42/yge8.png the bounds of view is NW & SE , so i test they points if is in polygons -> return false, However you see this polygon and i need to know that see this polygon Commented Oct 18, 2015 at 15:31

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Use the overlaps method of https://geophp.net/ to check if the polygon overlaps the rectangle defined by your map bounds.

See also https://en.wikipedia.org/wiki/DE-9IM to learn the difference between "overlapping" and "intersecting".

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