[postgis-devel] Xing Lin's SoC project (raster support)

Tim Keitt tkeitt at gmail.com
Wed Jul 11 15:04:07 PDT 2007


On 7/11/07, Paul Ramsey <pramsey at refractions.net> wrote:
> More specifically, there is a lot of talk about "user defined types" in
> this document, but the model does not really require any -- the whole
> thing can be done with relations.  Doing it as UDT's requires lots of
> book-keeping code for accessors to the properties of the types, doing it
> as relations does not.
>
> The same thing could be said about geometry, of course, but the
> difference is that geometry objects have a unitary structure that only
> makes sense in aggregate, so breaking them up is wasteful -- you have to
> put them back together again before they are useful.
>
> This is less true of these georasters, and in fact they will be somewhat
> broken up anyways, into bands, for example.  Why not start this process
> by building the whole thing as a relational model and then see what
> doesn't work well and needs a UDT for efficiency?

That sounds like it could simplify things and perhaps speed up a
prototype implementation. Xing -- what do you think?

THK

>
> P
>
> Paul Ramsey wrote:
> > I'm a little worried at the quantity of this document that is copied
> > verbatim from the Oracle Georaster documentation.  I mean, are we just
> > cribbing their whole design directly?  The Oracle model is pretty, but
> > it breaks up the rasters into an internal relational model, which pretty
> > much requires some sort of toolset for people to load/unload data.
> >
> > Second, the documentation stops with the model, it provides no
> > functions, or even hint of what functions will be done first. Providing
> > objects and no functions, or no data loader, is going to be a pure Waste
> > of Time. I know he's not going to have time to copy the complete set of
> > Georaster functions from Oracle, so an idea of what functions he plans
> > to do first is pretty important.
> >
> > PostGIS 0.1 had the types, it had input/output methods, and it had index
> > bindings.  If this implementation does not have a way of getting data in
> > and out, it's not going to be worth the time putting it together.
> >
> > P.
> >
> > Tim Keitt wrote:
> >>
> >> I'm attaching a proposal to add raster support to postgis. This is
> >> Xing Lin's SoC project. I'm hoping to get feedback on the spec and
> >> ideas for additions, modifications. Implementation is underway, but
> >> its not too late to make changes if people see significant problems or
> >> have suggestions.
> >>
> >> Cheers,
> >> Tim
> >>
> >>
> >> ------------------------------------------------------------------------
> >>
> >> _______________________________________________
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> >> postgis-devel at postgis.refractions.net
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> >
> >
>
>
> --
>
>    Paul Ramsey
>    Refractions Research
>    http://www.refractions.net
>    pramsey at refractions.net
>    Phone: 250-383-3022
>    Cell: 250-885-0632
> _______________________________________________
> postgis-devel mailing list
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>


-- 
Timothy H. Keitt, University of Texas at Austin
Contact info and schedule at http://www.keittlab.org/tkeitt/
Reprints at http://www.keittlab.org/tkeitt/papers/
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