[postgis-users] Buffer() Arc Tolerance

[Paul Ramsey]

For nitty gritty the details, sometime you have to "use the source, Luke".

 From PostGIS source:

     Geometry *g3 = g1->buffer(width);

So, PostGIS is not defining a stroke angle, or using anything other than 
the defaults, it's the GEOS code which is controlling what is done.

Hitting the GEOS code, source/operation/buffer is the place to go, but 
the documentation of DEFAULT_QUADRANT_SEGMENTS seems a bit thin. I can 
tell you that the default is 8, which is what PostGIS uses.

What do you mean by the arc tolerance? The number of vertices used to 
approximate the circular structure?

Richard_D_Levine at Raytheon.com wrote:

> If I use Buffer() on a point to approximate a geodetic circle, how do I
> determine the arc tolerance of the returned polygon to the circle?
> 
> Is there any documentation that contains answers to questions like this?
> I've read the PostGIS documentation cover to cover and the function
> explanations are at a very high level (mostly copied from the OGC spec.)
> 
> Thanks,
> 
> Rick