[postgis-users] The Old Who is using PostGIS survey again?

Chris Hermansen chris.hermansen at timberline.ca
Thu Jan 8 20:11:29 PST 2009

One of the things I would hope for - maybe THE thing I would hope for - 
is along the lines of a cookbook.  As in, a sample problem is stated, 
and a solution in PostGIS is developed.

By way of an example: you have a continuous land cover theme (polygons 
with no spaces between them).  You have some habitat polygons, which are 
not continuous (polygons, spaced apart from others).  You want to do the 
equivalent of an ArcInfo "union" - ie you want a single polygon theme 
where the land cover attributes and the habitat attributes (which would 
be null if there was no habitat polygon coincident with that land cover 

(The above has struck me as a difficult PostGIS problem, at least to 
compute quickly when there are large number of polygons involved.  The 
example given on the PostGIS wiki, using ST_UNION, seems to execute 
"somewhat" slowly for large datasets).

Some examples of good software oriented cookbooks I have known: the 
original Adobe Postscript green book; the O'Reilly Python cookbook; the 
Groovy book I bought recently whose title I can't remember but whose 
cover has some kind of sporty-looking vehicle on it.

Another thing I think is kind of neat about a cookbook approach - you 
could canvass this list for recipe ideas.


Chris Hermansen         mailto:chris.hermansen at timberline.ca
tel+1.604.714.2878 · fax+1.604.733.0631 · mob+1.778.232.0644
Timberline Natural Resource Group · http://www.timberline.ca
401 · 958 West 8th Avenue  · Vancouver BC · Canada · V5Z 1E5

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