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From Grant Ingersoll <>
Subject Re: [spatial] Cartesian "Tiers" nomenclature
Date Mon, 28 Dec 2009 17:42:14 GMT

On Dec 28, 2009, at 12:30 PM, Marvin Humphrey wrote:

> On Mon, Dec 28, 2009 at 11:31:14AM -0500, Grant Ingersoll wrote:
>> As some of you may know, I've been working pretty heavily on spatial stuff
>> lately.  
> Been watching from a distance, glad to see it.  :)
>> One of the things that has bothered me for a while is the use of the
>> terminology: cartesian tiers.  The thing is, I can't find any reference to
>> such a thing in any place other than Local Lucene and Patrick's white paper
>> on it.  Most GIS systems seem to either talk about grids or tiles when
>> describing this capability.
> I like "cartesian tiles".  Tiling is a familiar concept for anybody who's
> worked with Google Maps, and a little web searching tells me that "tiles" are
> also a concept in ArcGIS.  
> But I don't think "CartesianTile" would substitute properly for a
> "CartesianTier", would it?  
>    A CartesianTier is like a set of zoom levels on an interactive map

That's just how I've been explaining it b/c I think it is somewhat intuitive, but it isn't
necessarily correct.  In reality, it's a bunch of nested grids, with each grid being able
to be subdivided.  In practical purposes, I've seen people go down to like level 19, which
is more or less like looking at someone's backyard from a satellite.   

Microsoft has some docs on similar functionality:
 Alternate names there:  tiles, quad keys.

> So maybe use CartesianGrid for the zoom level, and CartesianTile as a single
> rectangle at whatever zoom (if such a class is needed)?
> Anecdotally, as a dabbler but not an expert, I can say that if you talked
> about "cartesian tiles" or "cartesian grid", I'd grok right away.  "Cartesian
> tier" would require an explanation.  
>> Do you think it is worth a name change?  This is about to get baked into
>> Solr and I would really prefer we choose names that the rest of the world
>> seems to understand.
> If it hasn't been baked in yet, then +1.  I do agree that it's important to
> use names that are already present in the hivemind rather than invent new
> ones.  Been there, done that, got sick of having to explain myself, went back
> to popular names...

It's semi-baked into Lucene already and people familiar w/ LocalLucene and LocalSolr.

> Marvin Humphrey

Grant Ingersoll

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