Geometry Boost List: Re: [geometry] bounding object calculation

Subject: Re: [geometry] bounding object calculation
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 2013-08-15 20:12:40

Mateusz Loskot wrote:
> On 15 August 2013 23:07, Barend Gehrels <barend_at_[hidden]> wrote:
>> On 15-8-2013 23:18, Adam Wulkiewicz wrote:
>>>
>>> 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:
>>>
[...]
>>>
>>> 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.
>>
>>
>> Agreed this name is beter and more generic. My objection was mainly that
>> envelope should not return circles, and because it is defined as such by
>> OGC.
>>
>> So yes, bounds sounds good to me as a generic term for bounding_box,
>> bounding_circle.
>> And yes, then envelope is just a special case of bounds.
>> Bounds is plural, maybe just boundary is enough?

I'll answer to Barend's email here if that's ok.

When I think of a boundry of a geometry it's more like a perimeter or an 
outer ring of a polygon. A geometry which closely encloses the 
internals, like the boundry of a country.

As for 'bounds'. I'm not an expert in english so feel free to prove me 
wrong, but according to:

http://www.thefreedictionary.com/bounds (2)
http://dictionary.reference.com/browse/bound (3)

may be used in plural form e.g. to describe some approximation of limits 
or a boundry.

Considering mathematical definition of bounds (probably this isn't fully 
correct since bounds describe sets, not geometries) we can probably say 
that 1d box represents 2 bounds (lower and upper), 2d Box 4 bounds 
(left, right, top, bottom), etc.

But I'm open to suggestion.

>
> There is also option like mbr for minimum bounding rectangle :)
>

I assume that this name could be a replacement for envelope which 
returns a Box. Am I right?

More generic, similar name could be mbg for minimum bounding geometry. 
Or bounding_geometry.

Regards,
Adam