Geometry Boost List: Re: [geometry] bounding object calculation (was: how to find the furthest point pair (= diameter) of a polygon?)

Subject: Re: [geometry] bounding object calculation (was: how to find the furthest point pair (= diameter) of a polygon?)
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 2013-08-15 17:18:26

Hi,

Barend Gehrels wrote:
>
>> bg::envelope() and bg::return_envelope() will probably handle other
>> bounding objects than Box. Am I right? Or some other name is choosen?
>
> As said earlier, envelope is an OGC algorithm with a specific meaning
> and the name is well-chosen. I guess more than 99% of the envelopes in
> your postbox is rectangular. The association is OK.
>
> So we might stick to PostGIS convention and call it
> minimum_bounding_circle, or replace the circle with a "ball"  or
> "nsphere" suffix to denote dimensions higher than 2.
>

I propose to choose a general name and implement a function calculating 
a bounding Geometry of arbitrary type. I'm using bounds() in the Index 
to return spatial index's bounding object. For example:

typedef model::box<..> Box;
Box box = return_bounds<Box>(some_geometry);
bounds(other_geometry, box);

typedef model::nsphere<..> Sph;
Sph sph = return_bounds<Sph>(some_geometry);
bounds(other_geometry, sph);

This function could calculate bounding boxes, nspheres and convex 
polygons/rings and in the future Geometries currently not available like 
oriented boxes, ellipsoids, capsules, cylinders and other frequently 
used in e.g. physics engines.

Regards,
Adam