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Subject: Re: [geometry] Support for geographic coordinate system
From: Barend Gehrels (barend_at_[hidden])
Date: 2014-11-17 16:28:24


Adam Wulkiewicz wrote On 14-11-2014 12:33:
> Hi,
> Menelaos Karavelas wrote:
>> On 14/11/2014 01:42 πμ, Adam Wulkiewicz wrote:
>>> Barend Gehrels wrote:
>>>> Adam Wulkiewicz wrote On 12-11-2014 1:48:
>>>>> bg::reference::sphere<>
>>>>> bg::reference::spheroid<>
>>>>> Or something like that, e.g. shorter.
>>>>> And then the tags could be:
>>>>> reference_spheroid_tag
>>>>> reference_sphere_tag : reference_spheroid_tag
>>>>> And in the future if we e.g. had model::sphere and Sphere concept,
>>>>> sphere_tag could be derived from reference_sphere_tag and used as
>>>>> a ReferenceSphere too.
>>>> This looks all OK to me. Explicitly adding reference makes it quite
>>>> clear - we reserve a model::sphere for later then too.
>>>> So this is then the ReferenceSphere Concept.
>> I have to admit I do not particularly like the name reference for the
>> reference system, as it very much reminds me of references in C++. I
>> would prefer something like
>> bg::reference_system::sphere<>
>> bg::reference_system::spheroid<> (I really do prefer this compared to
>> ellipsoid)
>> or
>> bg::geography_model::sphere<>
>> bg::geography_model::spheroid<>
>> Similarly for the tags. Among the two options I mention above I
>> prefer the second, but can happily live with the first.
> Yes, indeed the word "reference" may be confusing, though I think that
> we should just choose a name describing well the content. But ok,
> maybe we could pick something different. Note that the
> reference_system also has the word "reference" in it.
> I'd rather avoid the word geography. I know that the main purpose is
> to use it on in a GIS field but it should be general-purpose name.
> What do you think about:
> bg::reference_model::spheroid<>
> bg::ref_model::spheroid<>
> bg::rmodel::spheroid<>
> They also have "reference" in a name and the last "r" might be
> confused with "reverse".
> Since we already have bg::cs namespace, somehow related to the
> reference system. We could reuse this scheme:
> boost::geometry::rs::spheroid<>

The common abbreviation is srs (spatial reference system), so as we get
to that direction, I would certainly use that one. That would actually
look quite good.

> but should spheroid and sphere be included in reference systems
> (namespace)? They're rather models describing the ref systems. Though
> it's possible that we'd need a place for more code related to
> reference systems, EPSGs, SRIDs, etc. so this code could be put there.
> But then I'd put the models in:
> boost::geometry::rs::model::sphere<>
> boost::geometry::rs::model::spheroid<>
> Or just reuse the namespace cs for this:
> boost::geometry::cs::model::sphere<>
> boost::geometry::cs::model::spheroid<>
> which would be probably the most general choice. The question is:
> could additional things be put in the bg::cs namespace?

I think I would prefer the srs namespace.

Regards, Barend

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