The @, and other operators such as &&, work on the bounding boxes of
geometries. The st_xxx functions additionally do calculations using the
actual geometries themselves...
-Josh
Frank Durstewitz wrote:
Hi,
can someone please explain, what the difference between
WHERE ST_CONTAINS(b.geom, e
There's two ways to overlay data from PostGIS into Google Maps. As an
image overlay (eg WMS), or as vector overlays (if you don't have tons of
complex data in one view).
WMS:
Assuming you are gonna use Google Maps proper, versus OpenLayers (which
would make things easier), check out wms236.js
ries overlap. I guess it would
depend on how parcels are "really" assigned to disticts - ie can the
assignment be replicated algorithmically?
Josh Livni wrote:
Well, and again assuming he doesn't mind getting the list of parcels
whose centroids intersect each district rather than
Well, and again assuming he doesn't mind getting the list of parcels
whose centroids intersect each district rather than the list of parcels
that intersect each district, checking for point-polygon intersection is
going to be faster than checking for polygon-polygon intersection. So
for speed
What are you trying to accomplish? Do you need to have a duplicate
style geometry in the people table, or can you just make a join table
and get people and geometries associated more dynamically each query?
I guess I'm confused about what your end goal is.
Of course others may not be... but
Not sure if this is the recommended solution, but I sometimes do a
buffer(geom,0) in this type of situation.
SELECT Area(ST_Buffer(GeomFromText('MultiPolygon( ((0 0,0 3,3 3,3 0,0
0)),((1 1,1 4,4
4,4 1,1 1)))'),0))
-Josh
[EMAIL PROTECTED] wrote:
Hi,
I'd like to compute the total area of
Assuming you have a postgis database, a table called 'lines' and a table
called 'polys', and in each there is a field called 'id' and a field
called 'the_geom' which holds the geometry, then you could try:
'SELECT id, AsText(the_geom) from lines' - which would give you two
columns back, one of
Kirk,
Of course I'm not sure how your database was backed up, but chances are
you can get your data back somehow.
I would first try a few things - if one in particular fails, it may help
others isolate the trouble if you can give specific errors it failed
with. The command examples in paren
Kevin,
Thanks for the followup - I guess I knew the ST_ functions wrapped the
spatial queries and wasn't thinking straight - however I never did the
actual tests to see that I've probably been slowing myself down where
keep my old habits and include the && in there. Interesting. Thanks!
-
Ah - that's probably what he meant - in which case I guessed wrong both
times :)
Since you mentioned the GiST index (and it may well be of use -- perhaps
he's got millions of sec_catch polygons), I just figured I'd point out
to Craigie that if indeed he does have such an index, to take advanta
Craigie,
Not 100% sure I parsed your question right. It's possible others may
also be confused. You say 'all the polys in sec_catch fall within a
single record of prim_catch' .. are you then wondering which polygon of
sec_1 it is that they all fall within?
Or maybe, what you're trying to a
I think running buffer(bunch_of_geoms,0) rather than
geomunion(bunch_of_geoms) might be faster.
That said, still seems it takes a bit long. If it were me I'd try
playing around by first creating a table with your results, eg:
'''create table simple_buffers as (
select simplify(buffer(simplif
Not exactly sure what you specifically mean by 'surface map', but
assuming it's raster based, you'll need to step outside of PostGIS to
create it.
You may be interested in this response from Bill Binko to a tangential
question I had some time ago:
http://postgis.refractions.net/pipermail/pos
I don't know the intricacies of that error, but you have a couple easy
options. For just the one county, like in your query - ditch the
distinct, eg:
SELECT extent(the_geom) FROM shp_precincts WHERE county_id=72;
For all counties, try pulling the geom data out in different style, eg:
SELECT di
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