[postgis-users] PostGIS analogues to ArcInfo geoprocessing functions

Martin Davis mbdavis at refractions.net
Thu Jan 29 17:27:24 PST 2009

Chris, generally I agree (especially if the code is written in Java...  
8^).  After I posted this I started thinking that probably a few more 
minutes/hours/days splunging through the C code would no doubt reveal 
much about how it actually works.  At the moment however I can't even 
tell if it is memory-only or whether it uses external files to hold 
intermediate results!

I look forward to some cleverer programmer than me figuring out how to 
integrate the Grass code with PostGIS...

Chris Hermansen wrote:
> Martin, Martin, Martin: code is the best documentation there is!  and
> besides, it's not written in Perl so how bad can it be :-)
> Martin Davis wrote:
>> Have you looked at the code?  I rest my case....
>> Paul Ramsey wrote:
>>> On Thu, Jan 29, 2009 at 8:42 AM, Martin Davis
>>> <mbdavis at refractions.net> wrote:
>>>> The basic approach to computing polygon overlays has been
>>>> well-understood
>>>> for a long time (although this does not imply well-documented!).  The
>>>> implementation however is quite tricky, especially if performance and
>>>> robustness is required.  There is a notable lack of open-source
>>>> existing
>>>> implementations - which should be an indication of just how
>>>> difficult this
>>>> really is.
>>> I believe the vector component of GRASS includes overlay (and of
>>> course the raster component does too).
>>> http://grass.itc.it/grass64/manuals/html64_user/v.overlay.html
>>> P.
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Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022

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