[gdal-dev] Layer operations, a proposal

Howard Butler hobu.inc at gmail.com
Wed Apr 18 10:28:05 EDT 2012

On Apr 17, 2012, at 4:42 PM, Ari Jolma wrote:

> Folks,
> I propose a set of new methods for OGR layers (see the PDF). I took the basic ideas from page http://courses.washington.edu/gis250/lessons/Model_Builder/ which seems rather comprehensive. I wrote the pseudo code myself quickly (thus it may not be optimal and may contain bugs - improvement suggestions are of course welcome).
> I was considering to write these in Perl (on top of the Perl bindings) but probably they could also be in OGR core. Code-wise they would probably go into ogrlayer.cpp.
> If there is support/interest, I assume I should submit this as a RFC (with a patch)?
> Best regards,


I'm excited by the functionality, but skeptical about having this specific functionality in OGR's core.  I don't want to be discouraging, but this seems like giant scope creep for OGR.  It would seem as though there are tons of cases where things would degenerate quite quickly, especially with regard to doing these kinds of operations on data sources that variably support different access patterns. More bugs about pathological geometry overlay problems would become our responsibility. Also, this functionality already exists in GRASS almost verbatim, correct?

Is it reasonable for this to start out as a commandline utility (ogralgebra or something) and see if some of the sharp points can be smoothed over before rolling this into core? I suppose this goes counter to your desire of having it accessible for SWIG languages though.

In short, I can see how this is a great functionality boon for us, but I can also see that we might suffer for it a bit in terms of maintenance and headache associated with doing stuff that is not so much our forte.


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