[postgis-devel] Xing Lin's SoC project (raster support)
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?
> 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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> Paul Ramsey
> Refractions Research
> pramsey at refractions.net
> Phone: 250-383-3022
> Cell: 250-885-0632
> postgis-devel mailing list
> postgis-devel at postgis.refractions.net
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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