Thanks Regina,
That works great.
Cheers
Will
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RH,
Yes this is the same as putting 2 geoms with the same meter projection into
ST_Distance. The transform effectively flattens out a small section of
space so you are measuring in cartesian space which is actually what you
want to do since it simplifies the math.
Your example below
On Wednesday 19 March 2008 14:00:44 Obe, Regina wrote:
This is a known issue which I think Mark Cave-Ayland is working on.
I think Mike Leahy had suggested using
ST_MemUnion as a work around.
Hope that helps,
Regina
My current thinking is that it's related to array access under PostgreSQL
Mark,
Can you think of anything wrong with using ST_MemUnion as a temporary
fix aside from the fact that I guess for larger unioning jobs it is
probably less efficient?
Has anyone tried the new 8.3.1 to see if it changes the below issue. I
don't see anything in the list of changes
Ok, nevermind I think I figured it out I used this
lower(regexp_replace(fieldname, '[[:digit:]]*[^[:alnum:]_]*', '', 'g'))
That seems to be working but if somebody thinks that is incorrect please let
me know
davidj2k wrote:
I am trying to make a select statement that compares the field to
On Thursday 20 March 2008 13:37:03 Obe, Regina wrote:
Mark,
Can you think of anything wrong with using ST_MemUnion as a temporary
fix aside from the fact that I guess for larger unioning jobs it is
probably less efficient?
I can't say that I've had much to do with that section of code - I
Thanks for the reply. I think I got it figured out. The projections I was
putting into distance() where in meters. I used a projection that is in
degrees and then transformed to meters. It appears to be working now.
I'm not sure I understand why?
This is what I had previously
geom =
Just tested by upgrading to 8.3.1 - doesn't make a difference. Actually
for example
When I do something like
SELECT ST_Union(the_geom)
FROM boszip
which glues all the boston zips into one MULTIPOLYGON it crashes the
whole PostgreSQL service forcing me to have to restart the service (or
at
Distance() always returns cartesian distance in whatever units it is fed.
If it is fed data that is in meters -- the output will be in meters. If it
is fed degrees -- the output will be in degrees and totally useless. I
don't quite understand the problem that you are having
On Thu, Mar 20, 2008
guys,
how many min. floating-points must a server hardware support for
postgresql+postgis? does postgresql+postgis do much floating-point
math to make a difference? can someone give postgresql+postgis
application examples that will require high floating-points?
thks, jzs
Hi R H,
Are you certain that your input geometries are in a meter projection?
David is correct. Distance() always returns the cartesian distance in
the *same* units as the input. It's impossible to input something in
meters in this function and get something in degrees.
Looking at your
John Smith wrote:
guys,
how many min. floating-points must a server hardware support for
postgresql+postgis? does postgresql+postgis do much floating-point
math to make a difference? can someone give postgresql+postgis
application examples that will require high floating-points?
thks, jzs
I do
My explanation wasn't that great. Below is what I did.
26912 projection is in meters (right?)select
AddGeometryColumn('table','geocode', 26912, 'POINT', 2);
update tableset geocode = PointFromText('POINT(' || longitude || ' ' ||
latitude || ')', 26912);
distance(geocode, geocode) returns
thks steve! sorry, i can't get more specific since still planning.
i got an old box supporting only 1 floating-point. i am thinking of a
typical mapping application- the usual bread-and-butter type, and
concerned that some heavy-duty raster-based math (i don't know what
yet) would be undoable??
Ah. So your first attempt is incorrect. When you first create your
geometries, you need to set the srid of your new geometries to the
projection they are currently in. Since your input is lat/long, you need
to set the srid of your new geometries to the lat/long projection.
*Then* you can
Is there any problem, or is it common, to add a view to the
geometry_columns table? I'm experimenting using zigGIS to add PostGIS
layers to an ArcGIS 9.2 project. It seems that zigGIS only sees
tables listed in geometry_columns (unlike Quantum GIS which sees
anything with a geometry column,
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