[postgis-users] function to check if a polygon is convex

Brent Wood pcreso at yahoo.com
Wed Mar 2 13:39:42 PST 2022


 Hi,
I'm not aware of such a function, but a simple workaround may be to create a convex hull from the polygon perimeter, then see if this is the same as the original polygon. Any concavities present in the original should ensure a difference.


Cheers,
Brent

    On Thursday, March 3, 2022, 10:16:14 AM GMT+13, B H <hemantbist at gmail.com> wrote:  
 
 Hi,How do I check if the polygon is convex in postgis?
Things I have tried before sending this email I could not find any function  like st_is_convex.I searched in google but  I could not find any user defined postgres function to check for convexity of polygon either.select st_convexhull(wkb_geometry) = wkb_geometry  -- this returns false for convex polygons also.

Other libraries e.g. CGAL seem to have it. So I am hoping that something is already available in postgis that I am missing.https://doc.cgal.org/Manual/3.1/doc_html/cgal_manual/Partition_2_ref/Function_convex_partition_is_valid_2.html
Best,HB_______________________________________________
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