# Geometry :

Subject: Re: [geometry] bounding object calculation
From: Mateusz Loskot (mateusz_at_[hidden])
Date: 2013-08-15 18:39:15

On 15 August 2013 23:07, Barend Gehrels <barend_at_[hidden]> wrote:
> On 15-8-2013 23:18, Adam Wulkiewicz wrote:
>> 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.
>
>
> 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?

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

Best regards,

```--
Mateusz  Loskot, http://mateusz.loskot.net
"Participation in this whole process is a form of torture" ~~ Szalony,
wspinanie.pl
```

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