Increase GeoJSON precision

[gorunovanton]

I've increased precision when working with GeoJSON due to false-positive polygon self-intersection in scenarios with two close points.

Dataset with false-positive self-intersection:
false_self_intersection.txt

[codeofsumit]

oh wow, thanks for your work on this! I can't seem to find documentation about the parameter passed to toGeoJSON - can you provide a link?

[themre]

very nice! perhaps put this in some constant so it can be override via settings?

[codeofsumit]

great idea @themre

[themre]

found reference to this precision parameter. we need to make sure from which version is this available:
https://github.com/Leaflet/Leaflet/blob/88dd22cfe89a209d19c061a813e99669844a921b/src/layer/GeoJSON.js#L292

[gorunovanton]

There is no information about a precision argument in the official Leaflet documentation of the .toGeoJson() method.

But i've found a pull request with it which was merged around one year ago into the Leaflet codebase:
Leaflet/Leaflet#5444

I don't think that putting this value into a constant is necessary due to how floating point operations are implemented in JS - JS always operates on FP numbers as double precision numbers and 15 is the amount of most significant digits in double precision numbers. This opinion based on two SO topics:
https://stackoverflow.com/questions/1458633/how-to-deal-with-floating-point-number-precision-in-javascript/3644302#3644302
https://stackoverflow.com/questions/28045787/how-many-decimal-places-does-the-primitive-float-and-double-support

[gorunovanton]

found that support of this parameter was added in Leaflet 1.1.0:
https://github.com/Leaflet/Leaflet/tree/v1.1.0