Re: [postgis-users] How to eliminate small gaps produced by ST_union?

[Dave Potts]

Have you considered curve smoothing or apply a small buffer around the
orginal data/

Sandro Santilli wrote:
> It will be _very_ slow.
> So much that you may prefer to make the topology persistent.
>
> Another approach I'd like to see implemented would be to expose a
> tolerance
> to the GEOS implemented functions. Basically exposing the GEOS
> PrecisionModel. By doing that you could specify a tolerance in the overlay
> operations and the result should never have gaps bigger than the given
> tolerance.
>
> --strk;
>
> On Thu, Oct 25, 2012 at 10:28:19AM -0700, pcr...@pcreso.com wrote:
>> My impression is that working topologies is slow, especially with large
>> datasets - lots of computation involved.
>>
>> How effective would this be with hundreds of thousands or millions or
>> small polygons?
>>
>> Just running ST_Union() takes hours to days.
>>
>> Thanks
>>
>> Brent Wood
>>
>> --- On Fri, 10/26/12, Sandro Santilli  wrote:
>>
>> From: Sandro Santilli 
>> Subject: Re: [postgis-users] How to eliminate small gaps produced by
>> ST_union?
>> To: "PostGIS Users Discussion" 
>> Date: Friday, October 26, 2012, 6:04 AM
>>
>> You may try to construct a topology within PostGIS-2.0, using
>> a small tolerance, and then get the geometries back.
>>
>> --strk;
>>
>> On Thu, Oct 25, 2012 at 05:54:05PM +0100, Alexandre Neto wrote:
>> > I'm trying to Aggregate\Dissolve a set of adjacent, but not touching
>> > polygons in Postgis. The geometries were created editing the Postgis
>> table
>> > in QGIS created, with snapping and avoid overlap in the layer.
>> >
>> > I used ST_Union like this:
>> >
>> > SELECT ST_Union(the_geom)
>> > FROM table;
>> >
>> > Small gaps similar to lines appear in the result. This happens when
>> the
>> > adjacent polygons do not share the exact same vertices.
>> >
>> > [image: Inline image 2]
>> > Is there a way to eliminate this "gaps" or "small angles" within
>> Postgis?
>> >
>> > I know that v.clean in GRASS can eliminate small angles, and correct
>> > topology, but that would mean I needed to copy the features to GRASS,
>> > correct them and copy it back to Postgis.
>> >
>> > Thanks in advance,
>> >
>> > Alexandre Neto
>>
>>
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Re: [postgis-users] Hibernate support

[Dave Potts]

hi,

 you need check out something called spatial hibernate at 
http://www.hibernatespatial.org/

It supports Postgis and other spatial databases.

Dave.
lineh arineh wrote:
> hello, 
>
> I would like to know if post GIS supports hibernate ? and also if it has
> authentication support?
>
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Re: [postgis-users] install template postgis 2

[Dave Potts]

I think you  need to set your LD_LIBRARY_PATH to include /usr/pgsql-9.2/lib
Icadedt wrote:
> Hi,
>
> postgresql 9.2 and postgis 2 are successfully installed in my linux centos
> 6.3.
> I would like to install postgis 2 template but i have this error message:
>
> template_postgis=# CREATE EXTENSION postgis;
> ERROR:  could not load library "/usr/pgsql-9.2/lib/postgis-2.0.so":
> /usr/pgsql-9.2/lib/postgis-2.0.so: undefined symbol: pj_get_spheroid_defn
>
>
>
>
> Please i dont understand, proj4 4.8 is installed
> Thanks
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Re: [postgis-users] st_closespoint weridness

[Dave Potts]

Martin Davis wrote:
> If the point is inside the polygon, the distance between them is 0.
Hmm  I do not understand, then nearest point should be along the boundary
of the polygon.

> Can't get closer than that!
>
> You may want to try ST_ClosestPoint(ST_Boundary(poly), point)

This worked, many thanks

Dave.
>
> On 10/5/2012 12:10 PM, Dave Potts wrote:
>> just tried a
>>
>> select st_closestpoint(poly,point) and got the result point
>>
>> The point is within a the closed polygon poly, the version is postgis
>> 2.0
>> is there any sane reason why this behave in this manner.  I had expected
>> to the value of the x/y coordinate pair from the polylgon that is
>> nearest
>> to point, not the value of point!
>>
>> Any suggestions as what I might be doing wrong?  or an suggestions for a
>> better way of doing this?
>>
>> regards
>>
>>
>> Dave.
>>
>
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[postgis-users] st_closespoint weridness

[Dave Potts]

just tried a

select st_closestpoint(poly,point) and got the result point

The point is within a the closed polygon poly, the version is postgis 2.0 
is there any sane reason why this behave in this manner.  I had expected
to the value of the x/y coordinate pair from the polylgon that is nearest
to point, not the value of point!

Any suggestions as what I might be doing wrong?  or an suggestions for a
better way of doing this?

regards


Dave.

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[postgis-users] st_closespoint weridness

[Dave Potts]

Just tried a

select st_closestpoint(poly,point)
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Re: [postgis-users] Segmenting a curved sausage shaped polygon

[Dave Potts]

Applying a buffer with a large -ve value creates an very small inter polygon.

Does anybody know how to create a centre line from a polygon in Postgis 2.0?

Dave Potts wrote:
>
>
> If got a curved sausage shaped polygon, it looks a bit like a letter 'C'.
>
> Is there any easy way of chopping it up in to about 5-7 segments of about
> the same length?
>
> Would applying a buffer with a -ve give line that could be segmented/
>
> Dave.
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>
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[postgis-users] Segmenting a curved sausage shaped polygon

[Dave Potts]

If got a curved sausage shaped polygon, it looks a bit like a letter 'C'.

Is there any easy way of chopping it up in to about 5-7 segments of about
the same length?

Would applying a buffer with a -ve give line that could be segmented/

Dave.
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Re: [postgis-users] Postgis 1.5 core dumps on GEOSIntersects with side location conflict

[Dave Potts]

I have used the jts library and have the same type of issue

In jts you would

1.  Try to use a buffer of 0.
2.  Try calling one of the simplify geom operations.

Dave.
Adam wrote:
> Running this query against Postgis 1.5 causes a core dump:
> SELECT ST_intersects(
>geomfromtext('POLYGON((31.904296875 67.32421875,14.58984375
> 67.32421875,12.744140625 65.830078125,33.75 66.09375,31.904296875
> 67.236328125,31.81640625 67.32421875,31.904296875 67.32421875))', 4326),
>geomfromtext('POLYGON((31.904296875 67.32421875,14.58984375
> 67.32421875,12.744140625 65.830078125,33.75 66.09375,31.904296875
> 67.236328125,31.81640625 67.32421875,31.904296875 67.32421875))', 4326)
> );
>
> Running against Postgis 2.0 gives the following error (much preferred to
> get an error than a core dump!):
> ERROR:  GEOSIntersects: TopologyException: side location conflict at
> 31.81640625 67.32421875
> CONTEXT:  SQL function "st_intersects" statement 1
>
> Both are using geos version: '3.3.5-CAPI-1.7.5'.
>
> Unfortunately upgrading to Postgis 2 is not an option for us.
> Our platform is Solaris 10 x86 using 64 bit builds.
>
>>From dbx the core file shows:
>   [1] 0x1b408d(0x1, 0x1, 0x474e5543432b2b00, 0xbe0170, 0xfd7fffdf8880,
> 0x1b408d), at 0x1b408d
>   [2] _Unwind_RaiseException_Body(0x0, 0x0, 0x0, 0x0, 0x0, 0x0), at
> 0xfd7ffec416bc
>   [3] _SUNW_Unwind_RaiseException(0x0, 0x0, 0x0, 0x0, 0x0, 0x0), at
> 0xfd7ffec418a9
>   [4] __cxa_throw(obj = (nil), tinfo = (nil), dest = (nil)), line 75 in
> "eh_throw.cc"
>   [5] geos::geomgraph::EdgeEndStar::propagateSideLabels(this =
> 0xfd7ffe6e2a00, geomIndex = 0), line 69 in "new_allocator.h"
>   [6]
> _ZN4geos9geomgraph11EdgeEndStar16computeLabellingEPSt6vectorIPNS0_13GeometryGraphESaIS4_EE(this
> = 0x91bc10, geomGraph = 0xfd7fffdf8e18), line 88 in "EdgeEndStar.cpp"
>   [7] geos::operation::relate::RelateComputer::labelNodeEdges(this =
> 0xfd7fffdf8e30), line 327 in "RelateComputer.cpp"
>   [8] geos::operation::relate::RelateComputer::computeIM(this =
> 0xfd7fffdf8e30), line 131 in "RelateComputer.cpp"
>   [9] geos::operation::relate::RelateOp::relate(a = (nil), b = (nil)),
> line
> 43 in "RelateOp.cpp"
>   [10] geos::geom::Geometry::intersects(this = 0x91b598, g = 0x91b638),
> line 191 in "memory"
>   [11] GEOSIntersects_r(extHandle = 0x91d100, g1 = (nil), g2 = (nil)),
> line
> 351 in "geos_ts_c.cpp"
>   [12] GEOSIntersects(g1 = (nil), g2 = (nil)), line 139 in "geos_c.cpp"
>   [13] intersects(fcinfo = 0xfd7fffdf9110), line 2322 in
> "lwgeom_geos.c"
>   [14] ExecMakeFunctionResult(fcache = 0xfd7fffdf90d0, econtext =
> 0xbd5740, isNull = 0xbd6c28 "", isDone = (nil)), at 0x5a9d88
>   [15] ExecEvalAnd(andExpr = (nil), econtext = 0xbd5740, isNull = 0xbd6c28
> "", isDone = (nil)), at 0x5aaf23
>   [16] ExecProject(projInfo = 0xbd6c40, isDone = 0xfd7fffdf95bc), at
> 0x5ae659
>   [17] ExecResult(node = 0xbd5630), at 0x5ba7d0
>   [18] ExecProcNode(node = 0xbd5630), at 0x5a77ec
>   [19] standard_ExecutorRun(queryDesc = 0xbcd2e8, direction =
> ForwardScanDirection, count = 1), at 0x5a550c
>   [20] fmgr_sql(fcinfo = 0xfd7fffdf9880), at 0x5b1529
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[postgis-users] speeding up a postgis/postgres application

[Dave Potts]

I have java/hibernate/postgis application, running it, it takes about 20
mins to generate a result.

Running a system monitor on it,  I can see 2 of the 8 cpu spiking at 100%.

A strace indicates a lot of recv/send network traffic for this application.

The memory foot print is a constant

With out wanting to do a rewrite, is there any millage to telling this
application to use local connection to the database so that I avoid going
through the network stack?

Would increasing any of the memory limits in a standard Postgres set up help?

I have already rewritten all of the nearest neighbours of the queries that
say something like

select  blah blah order by distance

with calls to st_dwithin

I use bounding boxes where possible to limit the generated results.

All input  geometries have been  simplified where possible.

I am wondering if its worth caching some of the results of the select
statements in a hash table to avoid the costs of lookups.

Any suggestions greatfuly received?



Dave.

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[postgis-users] simplifying a polygon

[Dave Potts]

I have polygon made up of many different points,it some cases its rather
to accurate for my requirments,i.e. its generating a lot points to
describe a minor change.

I had throught that by saying something like


select ((st_dumppoints(
(st_intersection(ST_Segmentize(st_exteriorRing(jt.the_Geom),7),pa.the_geom))
)).geom) as the_geom from
 journey_table jt, coast_polygon  pa where  jt.generation=1

Would give me minmum list of data points for describing a polygon.  What
it does give me long gap, 3 coordinates, another long grap then another 3
coorindates etc

Where these 3 coordinates are they close together.  What I had hope to get
list the lowest number points that would be useful to describe a polygon.

Q.  Is there a better way of doing this.

Dave.


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Re: [postgis-users] Postgis rasters in OpenLayers?

[Dave Potts]

On 15/08/11 18:53, Pierre Racine wrote:

Use geoserver which can make a request to a postgis database and supply
data as  wfs or wms servers.  You can then use openlayers to access the
wfs/wms server
> I don't think there is anything in OpenLayer able to "speak" directly with 
> PostGIS... You need something in between able to deliver tiles. If your php 
> code can do that... But why trying to reinvent a tile server other than 
> MapServer or GeoServer?
>
> Pierre
>
>> -Original Message-
>> From: postgis-users-boun...@postgis.refractions.net [mailto:postgis-users-
>> boun...@postgis.refractions.net] On Behalf Of Vishal Mehta
>> Sent: Monday, August 15, 2011 1:43 PM
>> To: postgis-users@postgis.refractions.net
>> Cc: Eric Kemp-Benedict; Douglas Wang
>> Subject: [postgis-users] Postgis rasters in OpenLayers?
>>
>> Can anyone tell me if Postgis rasters can be displayed in OpenLayers?
>>
>>
>>
>> We are trying to develop a web-gis stack (so far Postggresql - Postgis - PhP 
>> -
>> OpenLayers) on an external server. I'm wondering if we can have raster
>> functionality as well as display with postgis alone as the map 
>> server...without
>> using Geoserver of Mapserver.
>>
>>
>>
>> Thank you,
>>
>> Vishal
>>
>>
>>
>> Vishal K. Mehta  , Ph.D.
>>
>> Staff Scientist,
>>
>> Stockholm Environment Institute-US
>>
>> 400 F St, Davis, CA 95616
>>
>> http://sei-us.org/
>>
>>
>>
>>
>>
>>
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Re: [postgis-users] Can save but not retrieve using Hibernate+PostGIS+JTS

[dave . potts]

Hi

Have you checked in the postgres database logs?

There might be a clue in there as to why it is not working

> El Thursday 26 August 2010, Paulo Angelo escribió:
>> Hi Ppl,
>>
>>   I'm getting a weird problem. I can save a Geometry type through
>> Hibernate
>> but I can't retrieve it.
>>
>>  WKTReader fromText = new WKTReader();
>>  Geometry geom = fromText.read("POLYGON((0 0,0 3,3 3,3 0,0 0))");
>> Session session = dao.newSession();
>> Transaction tx =  dao.beginTransaction(session);
>> Query q = session.createQuery("select f from Geometries f");
>> List list = q.list();
>> Poligono to = (Poligono) lista.get(0);
>> dao.commitTransaction(session, tx);
>> to.setPoli(geom);
>> System.out.println(to.getPoli().toString());  // Apears "POLYGON ((0 0,
>> 0
>> 3, 3 3, 3 0, 0 0))"
>> dao.alterar(to, null, null);
>>  // I can see via SQL that it saves correctly
>
> And have you checked that it appears in the database after the commit?
> Maybe
> the commit is not really commited (can't see why, though).
>
>> // Now, retrieve
>> session = dao.newSession();
>> tx =  dao.beginTransaction(session);
>> q = session.createQuery("select f from Geometries f");
>> list = q.list();
>> to = (Poligono) lista.get(0);
>> dao.commitTransaction(session, tx);
>> System.out.println(to.getPoli().toString());
>>  // Get a *NullPointerException*, because to.getPoli() is null
>>
>
> Have you tried debugging step by step checking that all variables are ok?
> Are
> you sure that "to" is not null instead of to.getPoli()?
>
> Have you tried using Criteria instead of hql? Maybe it is a conversion
> problem
> between geometry types.
>
> Could it be that closing/commiting the transaction is the problem? If
> hibernate didn't get all the data on one shot, closing the transaction
> makes
> hibernate unable to get more info from the database.
>
> Anyway, if you rollback a read-only transaction instead committing,
> hibernate
> goes faster.
>
>
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> Área de Operaciones
>
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> Tfno: +34 954 51 75 77 / +34 607 43 74 27
> Fax: +34 954 51 64 73
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Re: [postgis-users] Problems compiling Postgis from source in Ubuntu 9.10

[Dave Potts]

Mark Cave-Ayland wrote:

Has anybody read this web page ?

http://workingonnothing.blogspot.com/2009/08/setting-up-ubuntu-server-installig.html

Its somebodies successful attempt to install postgis 1-4.0 using the 
installed version of 8.3 on ubuntu Jaunty


Dave.

Roger André wrote:


Hi Mark,

I see from the Changelog that you committed many of the pgxs updates, 
so thanks for the response.  A couple points I'd like to clarify.


1. I have not installed ANY Postgresql code from aptitude, nor do I 
wish to.  Everything is fresh source code installed under /usr/local, 
and I would very much like to keep it that way.  You're right that 
there is another pg_config in /usr/bin/pg_config though, but I have 
no idea how it got there.  It's also strange that when I go through 
the locations specified by /usr/bin/pg_config, only some of them 
exist.  Looks like some sort of partial install, or something.  
aptitude also has no record of installing any postgres* package, so 
not sure how it got there.


2. Totally willing to grant you that my configure options might be 
incorrect for PostGIS 1.4. I didn't realize they had changed from 1.3 
to 1.4.  I'll have a closer look at the ./configure --help output to 
make sure I specify them correctly.   Would help if I pointed to the 
right pg_config. ;)


3. I am going to clean out all traces of the Ubuntu package on the 
system, and then will see if I can get the source to compile properly.


Thanks again,

Roger


Hi Roger,

I think it's related to the fact that multiple packages in Debian 
install pg_config but not necessarily with the correct Makefile. I 
have a feeling it is related to the libpq-dev package but it's quite 
difficult to test unless you reinstall a machine from scratch :(


Glad that you managed to get it all installed though.


ATB,

Mark.



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Re: [postgis-users] Absolute Beginner

[Dave Potts]

Bob Pawley wrote:

I suspect your not using the latest version of postgis.  The command 
select postgis_version(); will return which version use are using.


D.

Thanks Regina

My version of PostgreSQL has no functions that start with ST_ such as 
ST_GeomFromText.


I removed the ST_ from the code you suggested making it GeomFromText 
and it worked well.


What does the ST_ signify??

Bob
- Original Message - From: "Obe, Regina" 
<[EMAIL PROTECTED]>

To: "PostGIS Users Discussion" 
Sent: Tuesday, April 22, 2008 5:21 AM
Subject: RE: [postgis-users] Absolute Beginner


Bob,

Unfortunately I'm not too familiar with Delphi (aside from its some
Pascal derivative) and I guess no one is in this group since no one
responded to your question.

I guess it depends what Delphi is expecting for the Canvas - e.g. can it
use SVG maybe or most unlikely (WKT  or WKB representations).  At
anyrate I suspect you are more likely to find Delphi plugins for
rendering SVG than any other format output by PostGIS.

If you can find SVG plugins, there is an asSVG function in PostGIS that
may prove useful to you.

As far as storing the path, you could put it in your database as a
LINESTRING of the form

INSERT INTO temppath(fieldname)
VALUES(ST_GeomFromText('LINESTRING(1 2,3 12)'))

You can ignore use of SRID since you don't care about Geography.

Then query it as SVG format with

SELECT AsSVG(fieldname)
FROM temppath

or expand it out to x and y with something like

SELECT somekeyfield, ST_x(the_geom) as x, ST_y(the_geom) as y
FROM
(SELECT somekeyfield, ST_PointN(fieldname, generate_series(1,
ST_numpoints(fieldname)) As the_geom
FROM temppath)  as foo

That will give you the x and y coordinates of each point of the line
string (with all belonging to the same linestring having
the same somekeyfield

and then you can just plot the x and y on canvas.

Hope that helps,
Regina








-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Bob
Pawley
Sent: Monday, April 21, 2008 1:25 PM
To: PostGIS Users Discussion
Subject: [postgis-users] Absolute Beginner

I know that most, if not all, on this list are interested in the
geography
side of GIS.

However, I have a question on the geometry side.

I have a Delphi Canvas that I need to connect to a PostgreSQL database.

What is the minimum table structure that is needed to hold the vector
coordinates such as this path ((1,2), (3, 12)) so that it will draw the
line
in Delphi?

Perhaps the Delphi knowledgeable people can let me know if the following
query is any where near correct to accomplish this action.

Thanks in advance.

Bob
PSQLQuery1.Close;
 PSQLQuery1.SQL.Clear;
 PSQLQuery1.SQL.Add ('Select * fieldname ');
 PSQLQuery1.SQL.Add ('FROM temppath');
 PSQLQuery1.Prepare;
 PSQLQuery1.Open;
 PSQLQuery1.First ;
 i2:= PSQLQuery1.FieldByName('fieldname').AsInteger ;
 testfrm:= IntToStr(i2);

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[postgis-users] Opensource Toplink and Postgis(Java/JPA question)

[Dave Potts]

Has anybody had any success with the free version of Toplink and 
Postgis? to access a database


Toplink comes in two versions one for $$$ and a free version,  the free 
version does not seem to  support the @Convert annotation that is 
required to register the postgis Geometry type.


Without Convert type, what appears to happen is that toplink uses 
refflection to deterimne the data type from the postpis jdbc driver, it 
then bails out with an error.


Any suggestions?

If I had my choice then I would use Hibernate, but my project manager 
had other ideas :-(


Dave.
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Re: [postgis-users] PostGIS + Hibernate Quick Start

[Dave Potts]

Hi

I have used both hibernate/postgis setups

Whille its true that the hibernate postgis setup is in SVN I did'nt 
discover a source link to Hibernate Spatial (please correct if I am wrong).


Both products allow you access to postgis goemtry data structures, but I 
found the postgis hibernate version from the postgis site would not 
allow me to make querries using the foo: notation, pehaps it was my set 
up,  I am not sure.


But I managed to get the  http://www.hibernatespatial.org to work 
correctly, so I would suggest that you use that.


Dave.


Karel Maesen wrote:

Hi Alan,

I wrote a Hibernate extension for spatial databases, called Hibernate 
Spatial. You can find the project at http://www.hibernatespatial.org/ 
. I think it has what you're looking for.


Regards,

Karel Maesen
Geovise BVBA

On 27 Mar 2008, at 21:28, Alan Gutierrez wrote:
I'd like to get started with PostGIS though Hibernate. However, there 
is not much to start with.


There is a PowerPoint discussing how the British Columbia Digital 
Road Atlas uses Hibernate to bridget between PostGIS and Java 
Topology Suite geometries.


http://www.foss4g2007.org/presentations/view.php?abstract_id=118

There is a dash of example code at the PostGIS website.

http://postgis.refractions.net/support/wiki/index.php?SpatialEJB3

It seems to extend the PostgreSQL Hibernate dialect and it might be 
all that is needed to obtain full PostGIS support, but I'm uncertain.


Any guidance?

Alan

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Re: [postgis-users] postgis mapserver boolean expressions [SOLVED]

[Dave Potts]

After some hacking

The syntax

   '[castle]'  =~ /t/


Does the trick, horrible and not very clear for the beginner there must 
be a better way of writing a test for  boolean expression!

D.



David Potts wrote:

Hi
Is there a problem with the use of the postgres boolean type in mapserver?

I have a data type of type boolean in my database type called castle

I have tried to use the following syntax(see below) , I would have assumed
that if pt.castle was set to true, then this layer would have been drawn

 STATUS DEFAULT
DEBUG  ON
CONNECTIONTYPE POSTGIS
CONNECTION "dbname=dday_kent user=dp42 host=localhost
port=5432"
DATA "os_ngr from (
select pt.place_id, pt.place_name,pt.os_ngr as
os_ngr ,pt.castle as castle, pt.manor
from place_table pt  where pt.os_ngr is not null
)
as foo using srid=27700 using unique place_id"
CLASS
LABEL
SIZE large
OUTLINECOLOR 255 255 0
END
NAME "Castle"
SIZE 40
EXPRESSION  ( '[castle]' eq  't' )
OUTLINECOLOR 0 255 0
END


I have tried expresions such as

"[castle] = "1"
"[castle] = "t"
"[castle] = "TRUE"

nothing seems to make a difference, the expression always returns false.

I am using mapserver 5.02 and postgis 1.32.

Has anybody seen anything like this before?

Dave.

  


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Re: [postgis-users] How can I make geo-reference

[Dave Potts]

Amrita p wrote:
You need what is called a projection file, it defines the projection to 
be used with a given a shape file, see 
http://en.wikipedia.org/wiki/Shapefile for the details.



The following is a shape file for the uk ordnace survey, if you shape 
file is called foo, then you need to create a file called foo.shp, with 
this content



PROJCS["British_National_Grid",GEOGCS["GCS_OSGB_1936",DATUM["D_OSGB_1936",SPHEROID["Airy_1830",6377563.396,299.3249646]],PRIMEM["Greenwich",0.0],UNIT["Degre
e",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",40.0],PARAMETER["False_Northing",-10.0],PARAMETER["Central_Merid
ian",-2.0],PARAMETER["Scale_Factor",0.999601272],PARAMETER["Latitude_Of_Origin",49.0],UNIT["Meter",1.0]]

If you need the text for a different projection system, have a look at 
the contents of the table spatial_ref_sys, you should find something 
that matches in there.


D.

 
Hi All!


I have  file with extension .shp, .dbf, .shx but this shape file in 
not geo-reference.


I want to make the shape file geo-reference...
How can I do the above..
If any body has any idea abt this please help me..

Thanks in advance.

Amrita



Reliance Mobile 
 





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[postgis-users] difference between contains and within

[Dave Potts]

I trying to work out the number of points that spaitially inside a 
polygon, looking at the manual there are two functions that seem to do 
the right thing, contains and within.


Q. Whats the difference between the two functions?
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Re: [postgis-users] Discovering where roads cross rivers

[Dave Potts]

Paul Ramsey wrote:
SELECT m.name from transport m, rivers r where 
ST_Intersects(m.the_geom, r.the_geom);



On 15-Sep-07, at 8:03 AM, Dave Potts wrote:

I am trying to discover all the data points when a river system 
crosses a road system, my data is expressed as two different 
shapefiles,  I had assumed that it was just a case of calling  the 
Intersection method


eg. select m.name from transport m , rivers r where 
Intersection(r.the_geom,m.the_geom) = 't';


But I get a 'parse error- invaid geometry when I try this, is this 
the correct way of doing this?


Dave.





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Thank you, worked a treat!

Dave.
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[postgis-users] Discovering where roads cross rivers

[Dave Potts]

I am trying to discover all the data points when a river system crosses 
a road system, my data is expressed as two different shapefiles,  I had 
assumed that it was just a case of calling  the Intersection method


eg. select m.name from transport m , rivers r where 
Intersection(r.the_geom,m.the_geom) = 't';


But I get a 'parse error- invaid geometry when I try this, is this the 
correct way of doing this?


Dave.
  


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Re: [postgis-users] libiconv problem

[Dave Potts]

Dave Potts wrote:

Jeff Stubbs wrote:

Hi,

I'm working within the MacPorts system on OS X. The portfile for 
postgis is currently at version 1.2.1, and I'm trying to update it to 
the latest (1.3.1). PostGIS builds and installs but is linking to the 
libiconv library in /usr/lib, instead of the libiconv port in 
/opt/local/lib. The MacPorts system tries to be self contained with 
it's dependencies, so I have been trying to tweak the install to rely 
on the MP install of libiconv. PostGIS recognizes that proj, geos, 
and postgresql are installed in the /opt/local directories.


I saw a thread from December-2005 that another user was having a 
similar problem with a Debian system, and I've been cautiously trying 
the suggestions to workaround the issues, but with no luck. I'm a 
relative nu-bee with modifying makefiles, so, no doubt, I'm missing 
something blindingly obvious. Can a more experienced user or 
developer, throw some light on the issue for me?


Thanks for your time,

Jeff

 
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Hi Jeff

Check out redo_prebinding or have a look at some off the envronment 
options listed under dyld( man dyld for details)



redo_prebinding allows to changes the settings for a binary program, 
the settings for dyld effect where a given program looks for files.



Dave.
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Another though, if you want to know which library a program uses, use 
otool -L


If you want to know what files a program is using, run it under ktrace 
and kdump, these program wil list any system calls your program makes, 
eg opening a file(library, data etc)



Dave.
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Re: [postgis-users] libiconv problem

[Dave Potts]

Jeff Stubbs wrote:

Hi,

I'm working within the MacPorts system on OS X. The portfile for 
postgis is currently at version 1.2.1, and I'm trying to update it to 
the latest (1.3.1). PostGIS builds and installs but is linking to the 
libiconv library in /usr/lib, instead of the libiconv port in 
/opt/local/lib. The MacPorts system tries to be self contained with 
it's dependencies, so I have been trying to tweak the install to rely 
on the MP install of libiconv. PostGIS recognizes that proj, geos, and 
postgresql are installed in the /opt/local directories.


I saw a thread from December-2005 that another user was having a 
similar problem with a Debian system, and I've been cautiously trying 
the suggestions to workaround the issues, but with no luck. I'm a 
relative nu-bee with modifying makefiles, so, no doubt, I'm missing 
something blindingly obvious. Can a more experienced user or 
developer, throw some light on the issue for me?


Thanks for your time,

Jeff

 
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Hi Jeff

Check out redo_prebinding or have a look at some off the envronment 
options listed under dyld( man dyld for details)



redo_prebinding allows to changes the settings for a binary program, the 
settings for dyld effect where a given program looks for files.



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Re: [postgis-users] Hibernate Tools and PostGIS

[Dave Potts]

Norman Barker wrote:

Hi,

I have extended the postgis hibernate tools so that now when you reverse
engineer a postgis database the entity pojos are marked up with custom
geometry annotation (hibernate mapping) - this really wasn't hard and
just amended an existing patch - this will go into Hibernate shortly.

However I really need some direction now!

We have in the spatial domain

1) Geometry persistence and table generation
2) Hibernate criteria queries
3) spatial dialect (so spatial object queries)

The next logical step is to follow the JBoss seam generator examples and
auto-generate a web app as this is similar to the existing toolset in
hibernate tools.

However I need to know what you want (if at all you are interested), is
generating a web app (a la Rails) of use, or would you prefer a WFS /
GeoJSON generator or ANOther use for the entities mapped from a
database?  Perhaps a UML modeler which creates the pojos that then
creates the PostGIS db would be of interest?

I don't really use this for work, so some real direction from the
community would be appreciated (cc'd Chris Hodgson as I know he uses
hibernate in this way (but not this codebase)).

Thanks,

Norman 
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VERY nice bit of work, but I think you need an example with the postgis 
term in the where clause,  I have just spent several hours trying to 
work this out.

eg something like might help

select distinct dist from DistanceDTO as dist, DistanceDTO as src where 
spatial.Contains(dist.osNGR,src.osNGR)='t';


Granted the dianostics from Hibernate are rather unclear.

Dave.
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Re: [postgis-users] Tools to view data stored in PostGIS

[Dave Potts]

Milo van der Linden wrote:
HI

You could always try grass http://grass.itc.it/ or perhaps mapserver 
http://mapserver.gis.umn.edu/


Dave.

Hello Thorsten!

Best available at this moment would be QuantumGIS, google it and 
download. Have fun!


Kind regards,


Thorsten Kraus schreef:

Hi all,

what software tools do you use to view geometric data stored in 
PostGIS? I search a tool which directly connects to the PostGIS 
database and which allows me to select a table which should be 
rendered. Are there some non commercial tools available?


Regards,
Thorstn
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[postgis-users] within function

[Dave Potts]

I have a table with a list of places described as Geometry type POINT 
and a table loaded from a shape file,  which takes the form of target 
(ie several inscribed circles), each is encoded as a MULTIPOLYGON.  I am 
attempting to discover which point lie within within these circle.


I had assumed that something like

select place_name,gid,id,gridcode,area(the_geom) , 
within(the_geom,os_ngr) from shptbl,place_table wherein (the_geom,os_ngr) ;


would return every geometry ie os_ngr which is within the geometry  
boundries of the_geom.


Where place_name,os_ngr come from place_table and the_geom comes from 
the table shptbl.


Both geometry have the same sri, no errors are listed in the postgres 
log files.
I have assume that within covers data types of different types (ie POINT 
and MULTIPOLYGON)


Dave.
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Re: [postgis-users] Postgis FDO native driver

[Dave Potts]

I have a table with a list of places described as Geometry type POINT 
and a table loaded from a shape file,  which takes the form of target 
(ie several inscribed circles), each is encoded as a MULTIPOLYGON.  I am 
attempting to discover which point lie within within these circle.


I had assumed that something like

select place_name,gid,id,gridcode,area(the_geom) , 
within(the_geom,os_ngr) from shptbl,place_table wherein (the_geom,os_ngr) ;


would return every geometry ie os_ngr which is within the geometry  
boundries of the_geom.


Where place_name,os_ngr come from place_table and the_geom comes from 
the table shptbl.


Both geometry have the same sri, no errors are listed in the postgres 
log files. 

I have assume that within covers data types of different types (ie POINT 
and MULTIPOLYGON)


Dave.
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Re: [postgis-users] Units for distance function

[Dave Potts]

Michael Fuhr wrote:

On Fri, Jul 27, 2007 at 01:49:28AM +0100, Dave Potts wrote:
  
What units does the distance function use?  am I correct in thinking its 
derrived from the srid type of the geometry column?



Distance/st_distance returns the distance between two geometries
in whatever units the geometries use (meters, feet, degrees, etc.).

  
So in the case of the British national grid srid 2770  the correct unit 
to use is the meter



I assume you mean SRID 27700, in which case distances would be meters.

  

Thank You,  its always nice to have a guess confirmed

Dave.
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Re: AW: [postgis-users] PostGIS and Hibernate

[Dave Potts]

Thorsten Kraus wrote:
Can't help you with one, but with 2, it works for ME!

create a context.xml  file in your META-INT like
==



   



===
Put the hibernate config file in webapps/mma/WEB-INF/classes



   
   

   
   name="connection.datasource">java:/comp/env/jdbc/castleDB
   name="dialect">org.hibernate.dialect.PostgreSQLDialect

   true
   true
   name="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider


   true
   false
   false
   name="current_session_context_class">thread

   3
   3
   5
   1800

   
   
   
   resource="uk/co/pinan/mma/dto/OwnerMapDTO.hbm.xml"/>
   resource="uk/co/pinan/mma/dto/PlaceNameDTO.hbm.xml"/>

   
   
   
   


==
And use something like to map your files
==



http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd";>


   

   
   
 
   
   

   

   

   

   



Hi Andy,
 
thanks for this useful information. I read the ejb3spatial.pdf and 
have some further questions on this topic :)
 
1. You mentioned that Norman Barker has created a user type for 
Hibernate. Is this user type an official component of the Hibernate 
framework or is it an addition where no support from the Hibernate 
team is guaranteed?
 
2. The tutorial in the pdf uses JBoss as application server. In my 
project I use Tomcat. So Tomcat is not a full application server, I 
think it is not possible to use Hibernate for PostGIS access in my 
project without changing the application server. Is this right?
 
Thanks,

Thorsten

-Ursprüngliche Nachricht-
*Von:* [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Auftrag
von *Andy Dale
*Gesendet:* Freitag, 27. Juli 2007 09:10
*An:* PostGIS Users Discussion
*Betreff:* Re: [postgis-users] PostGIS and Hibernate

Hi Thorsten,

A person called Norman Barker has created a user type for
Hibernate, this can be accessed here
http://svn.refractions.net/postgis/trunk/java/ejb3/
also read the
ejb3spatial.pdf located here as it gives a example of how to use it.

Cheers,

Andy



On 27/07/07, *Thorsten Kraus* < [EMAIL PROTECTED]
> wrote:

Hi all,

currently I am working for a project which uses PostGIS to
store spatial objects in the backend of an web application
(Tomcat is used as servlet container). Some time ago I
searched the web for Hibernate support for PostGIS database
and its geographical objects, but found nothing suitable. So I
use Hibernate for non geographical attribute data and wrote
some JDBC code for accessing the geographical objects in
PostGIS. This hybrid structure of Hibernate and JDBC works
fine, but it would even be nicer and more flexible if there
was a possibility to handle all the database stuff with
Hibernate.

Can you tell me if there is Hibernate support for PostGIS
meanwhile? If yes, a piece of code or a link to a tutorial
would be pleasant.

Kind regards,
Thorsten


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[postgis-users] Units for distance function

[Dave Potts]

What units does the distance function use?  am I correct in thinking its 
derrived from the srid type of the geometry column?


So in the case of the British national grid srid 2770  the correct unit 
to use is the meter


Dave.
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Re: [postgis-users] Shapefile toolkit

[Dave Potts]

Stephen Woodbridge wrote:

Dave Potts wrote:

Is anybody aware of any tools to creat or manipulate shape files?

I have a shape file and I want to add some projection data to it


PostGIS is a good tool for this. Or if you are C language compatible 
you can get shapelib and write trivial tools for manipulating them. I 
do this all the time.


Question: what do you mean by: "add some projection data to it"?

Good question,  I have the .shp, .dbx and .shx files, but no .prj files.

Thanks for the tips.

Dave.


Shapefiles per say do not have projection information. ESRI Arc* 
tools, the newer ones anyway, create file.prj file but shapefiles 
themselves have no projection definition.


If on the other hand you have data that is in a different project and 
you would like to merge is with data from a different projection, then 
why not load it into postgis and multiple tables using shp2pgsql where 
each table has the appropriate srid set. Then do something like:


insert into tablea (select col1, col2, transform(the_geom, srid_from 
tablea) from tableb);


This will transform the data from tableb srid to tablea srid and 
insert it into tablea


then you can use pgsql2shp to dump the data back out to a shapefile.

-Steve
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[postgis-users] Shapefile toolkit

[Dave Potts]

Is anybody aware of any tools to creat or manipulate shape files?

I have a shape file and I want to add some projection data to it


regards

David
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