Re: Elevation Profiles

On Tue, Nov 30, 2004 at 01:44:15PM -0800, James Marca wrote:
> At approximately Tue, Nov 30, 2004 at 11:19:20AM +0100, strk <at> refractions.net wrote:
> > I premit I've not experience with elevation grid.
> 
> I'm also clueless on using elevation grids. But I'm going to comment
> and hope someone will correct my misinterpretations
> 
> > Anyhow, here is my imagined algorithm:
> > 
> > 	1: define a grid of C*R cells storing a list of Z values
> 
> Does it have to be a grid, or can it be any sort of tessellation, such
> as a Delaunay triangulation?  
>
> > 	2: populate the cells Z list using a geometry, where
> > 	   each vertex populates the cell it intersects
> 
> Couldn't the defining geometry create the Delaunay triangulation?  So
> that each valid elevation point (z value) inhabits its own triangle?

In this case each valid elevation point would define a vertex of a
triangle, wouldn't it ? After gathering all input geoms, and thus
vertexes the triangulation will need to be computed, connecting 
them. But is this worth the cost of doing it ? 

> 
> > 	3: elevate a geometry applying for each vertex 
> > 	   the average Z of the cell it intersects and
> > 	   the average Z of the whole grid for cells with
> > 	   no Z in list

problems with postgis.sql

Hello list,

while trying to load postgis.sql
I get the following
ERROR: could not load library "c:/ms4w/apps/pgsql75win/lib/libpostgis.dll"
although the file does exist.

I'm running WinXP SP2

thanks in advance,
 Fabio Fioravanti

Re: problems with postgis.sql

Dear Fabio ,

I am not a frequent user of PostGIS.

> ERROR: could not load library "c:/ms4w/apps/pgsql75win/lib/libpostgis.dll"
> although the file does exist.
>

But this error may be due to the permmision problem i.e make sure this
is owned by PostgreSQL superuser.

RE: problems with postgis.sql

 don't windoze paths use \'s not /'s ? Just a thought

________________________________

From: postgis-users-bounces <at> postgis.refractions.net on behalf of Fabio Fioravanti
Sent: Wed 12/1/2004 5:37 AM
To: postgis-users <at> postgis.refractions.net
Subject: [postgis-users] problems with postgis.sql

Hello list,

while trying to load postgis.sql
I get the following
ERROR: could not load library "c:/ms4w/apps/pgsql75win/lib/libpostgis.dll"
although the file does exist.

I'm running WinXP SP2

thanks in advance,
 Fabio Fioravanti
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postgis-users <at> postgis.refractions.net
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_______________________________________________
postgis-users mailing list

Re: problems with postgis.sql

This error message doesn't depend on \ or /.

On Windows this message - about 'libpostgis.dll' - is always with an '/'
----------------------------------------------------------------
TECHER Jean David
Responsable Informatique 01MAP
e-mail: davidtecher <at> yahoo.fr
site perso : http://techer.pascal.free.fr/postgis/
site pro: http://www.01map.com/download/
K-S:"The greatest trick the devil pulled off was convincing people he didn't
exist"
------------------------------------------------------------
----- Original Message -----
From: "Ethan Alpert" <ealpert <at> digitalglobe.com>
To: "PostGIS Users Discussion" <postgis-users <at> postgis.refractions.net>
Sent: Wednesday, December 01, 2004 3:34 PM
Subject: RE: [postgis-users] problems with postgis.sql

don't windoze paths use \'s not /'s ? Just a thought

________________________________

From: postgis-users-bounces <at> postgis.refractions.net on behalf of Fabio
Fioravanti
Sent: Wed 12/1/2004 5:37 AM
To: postgis-users <at> postgis.refractions.net
Subject: [postgis-users] problems with postgis.sql

Hello list,

geomunion question, unexpected behavior

I think the two queries below are both computing the union of the exact 
set of polygons; yet they are producing different results.

In the first case, I create the union of all at once.
This gives me a TopologyException.

In the second case, I group the polygons into smaller subsets, and create 
a geomunion of each - and then cerate a geomunion of the resulting 
subsets.  This works fine and gave me the expected results.

The polygons being unioned ( unionized?  ) are all the results of
the buffer() function being applied to MultiPoint objects; so I think
they're well-formed polygons.

Am I correct in guessing that this behavior is incorrect?
Any hints how to debug?

I could dump&send the data, but couldn't get it to fail with less than 720 
polygons yet.

     Thanks in advance
     Ron

fl=# explain analyze
      select geomunion(the_geom) from user_area_features;

NOTICE:  TopologyException: no outgoing dirEdge found (-84.2768,30.4646)
ERROR:  GEOS union() threw an error!
fl=#

RE: geomunion question, unexpected behavior

I had a lot of these types of problems previously and I upgraded to
0.9.0 and GEOS 2.0 to correct the problem. I did narrow my problem down
to GEOS having problems with Geometries that were the same. You may try
selecting distinct geometries to pass to geomunion.

You may want to make sure all your geometries are valid. Do a select
isvalid(the_geom) 

-e

-----Original Message-----
From: postgis-users-bounces <at> postgis.refractions.net
[mailto:postgis-users-bounces <at> postgis.refractions.net] On Behalf Of
rm_postgis <at> cheapcomplexdevices.com
Sent: Wednesday, December 01, 2004 10:18 AM
To: postgis-users <at> postgis.refractions.net
Subject: [postgis-users] geomunion question, unexpected behavior

I think the two queries below are both computing the union of the exact 
set of polygons; yet they are producing different results.

In the first case, I create the union of all at once.
This gives me a TopologyException.

In the second case, I group the polygons into smaller subsets, and
create 
a geomunion of each - and then cerate a geomunion of the resulting 
subsets.  This works fine and gave me the expected results.

Re: Guide to understanding GIS

Got a better place 

http://gisdevelopment.net/tutorials/index.htm

--

-- 
With Best Regards,
Vishal Kashyap.
Lead Software Developer,
http://saihertz.com,
http://vishalkashyap.tk

OT [GIS in Other Languages]

Dear all ,

Can GIS be programmed in 
Clippers , Foxpro  I mean can they have the same functionality as we
have in PostGIS

Just a query. 

--

-- 
With Best Regards,
Vishal Kashyap.
Lead Software Developer,
http://saihertz.com,
http://vishalkashyap.tk

Re: library loading error

When I rebooted this morning, downloaded FC3 kernel source to help with 
compiling madwifi, I now find that postgresql is _again_ no longer 
recognizing libgeos?!

Is there something more permanent I need to do than doing ldconfig 
/usr/lib as root?

Collin

collin wrote:
> I ran ldconfig -v. liblwgeom.so.1.0 was found, but libgeos.so.2.0.1 was 
> not.  I guess I may not have run it after all for /usr/local/lib. So I 
> ran it with /usr/local/lib.
> 
> After adding local/lib and rebooting, postgresql is now recognizing 
> geometries properly. Thanks!
> 
> Collin
> 
> strk <at> refractions.net wrote:
> 
>> On Tue, Nov 30, 2004 at 08:51:20AM -0800, collin wrote:
>>
>>> No, I ran it after geos,proj4,postgresql install, but before postgis 
>>> install.  Then I ran it again after postgis install.
>>>
>>> Should I have run it immediately after geos install?
>>
>>
>>