gmane.comp.gis.postgis

Re: Mapserver/Postgis connection and WMS query

manish sharma — 2013-05-19T02:23:13

Hi David

I am also trying to do the same, what u r into.

I have also one raster file in Postgis database and along with that some
vectors also , 

What I want is to clip that raster with vector layer and to visiulaize that
clipped raster in mapserver,

if u have done the same. ple help me also.

if u can mail me the complete flow that would be really appricated.

sharma.52004< at >gmail.com

Regards
Manish Sharma



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Re: postgis topology

Paragon Corporation — 2013-05-18T17:43:27

Is your schema called DP_TOPO2 or dp_topo2?
 
Stay away from upper or mixed case names for schemas, column names and
tables.  It will only cause you frustration in the long run.
 
That aside this looks like a bug in topology itself that it is not handling
mixed case, upper case schemas.  Please post a bug ticket as detailed here:
http://postgis.net/support
 
 
The topology code should be really doing SELECT
nextval('"DP_TOPO2".node_node_id_seq') 
 
but looks like its probably not using quote_ident to determine that.
 
Hope that helps,
Regina
http://www.postgis.us
http://postgis.net
 

  _____  

From: postgis-users-bounces< at >lists.osgeo.org
[mailto:postgis-users-bounces< at >lists.osgeo.org] On Behalf Of Eva Linhartová
Sent: Saturday, May 18, 2013 6:18 AM
To: postgis-users< at >lists.osgeo.org
Subject: [postgis-users] postgis topology


Hi, 
I'm trying to insert geometry data to topology structure. I tryed it on my
sample data before and it was ok, but now if I use polygon table with 7000
polygons or 20000 lines can't

postgis topology

Eva Linhartová — 2013-05-18T10:17:44

Hi,
I'm trying to insert geometry data to topology structure. I tryed it on my
sample data before and it was ok, but now if I use polygon table with 7000
polygons or 20000 lines can't work.

I get error like:

ERROR:  schema "dp_topo2" does not exist
LINE 1: SELECT nextval('DP_TOPO2.node_node_id_seq')

ERROR: schema "dp_topo2" does not exist
Stav SQL: 3F000

SET search_path TO dp, topology, public;
SELECT CreateTopology('DP_TOPO2',2065,0.005);  -- 1491 ms

SELECT AddTopoGeometryColumn('DP_TOPO2', 'dp', 'ku', 'topo', 'POLYGON');
 -- 301ms
SELECT AddTopoGeometryColumn('DP_TOPO2', 'dp', 'body', 'topo', 'POINT');
 -- 701ms
SELECT AddTopoGeometryColumn('DP_TOPO2', 'dp', 'plochy', 'topo',
'POLYGON'); -- 298ms
SELECT AddTopoGeometryColumn('DP_TOPO2', 'dp', 'linie', 'topo',
'LINESTRING'); -- 171ms


UPDATE ku SET topo = topology.toTopoGeom(geom, 'DP_TOPO2',1,0.005);  --
687ms
UPDATE body SET topo = topology.toTopoGeom(geom, 'DP_TOPO2',2,0.005); --
164274ms
UPDATE plochy  SET topo = topology.toTopoGeom(geom, 'DP_TOPO

Re: Strange behavior

2013-05-18T06:18:17

There are two issues here.  

I believe ST_AsText() does not return the full underlying precision of the point/line coordinates, so won't help resolve this.

Also, if you bear in mind your machine precision (or the Postgis coordinate precision - which may not be the same thing), the number of points on a linestring is finite, and makes the linestring actually a series of small steps. Think of it a bit like a series of pixels in a very fine raster. If horizontal or vertical, it works nicely, but any sort of diagonal & your line is only approximated. Two crossing diagonals do not necessarily have a pixel (point) in common.

A point using the value of pi as a coordinate - you can get very close, but "equals" is a meaningless operation.

Point on line intersections are therefore real number equality tests, and not reliable. Theoretically you can get different answers on 32/64 bit systems, or code compiled with different compilers (with different numerical precision), & if you export to any format that has reduce

Re: Strange behavior

Paragon Corporation — 2013-05-18T04:23:33

ST_AsText rounds data so what you get back is not to the precision actually
stored in your database.
 
Try using
ST_DWithin instead and adding in a small amount of buffer e.g.
ST_DWithin(geom, your_point,0.00001)
 
playing around with the distance.
 
We never rely on intersects for point - line checks because if you have
floating point junk it really screws up your calculations.
 
Leo and Regina
http://www.postgis.us

  _____  

From: postgis-users-bounces< at >lists.osgeo.org
[mailto:postgis-users-bounces< at >lists.osgeo.org] On Behalf Of Richard Cernava
Sent: Friday, May 17, 2013 7:40 PM
To: postgis-users< at >lists.osgeo.org
Subject: [postgis-users] Strange behavior


I'm trying to query if a point is present inside a MultiLineString. When I
run the following query I get very strange results in my opinion. If someone
could elaborate as to what's going on it would be very much appreciated!  

From this query I get a false and a true on the identical data. First I
check to see if the_geom intersects with my point and rec

Strange behavior

Richard Cernava — 2013-05-17T23:40:21

I'm trying to query if a point is present inside a MultiLineString. When I
run the following query I get very strange results in my opinion. If
someone could elaborate as to what's going on it would be very much
appreciated!

From this query I get a false and a true on the identical data. First I
check to see if the_geom intersects with my point and receive false. Second
I take the_geom and convert it to text and then compare it with my point
using ST_GeomFromText and get true. How is this possible? I've outputted
the result from the statement below.

SELECT fullname, ST_X(ST_StartPoint(ST_LineMerge(the_geom))),
ST_Y(ST_StartPoint(ST_LineMerge(the_geom))),
ST_AsText(the_geom) AS text,
ST_Intersects(the_geom, ST_GeomFromText('POINT(-122.837109 45.537746)',
4269)) AS fromdb,
ST_Intersects(ST_GeomFromText(ST_AsText(the_geom), 4269),
ST_GeomFromText('POINT(-122.837109 45.537746)', 4269)) AS fromtxt
from tiger_data.or_edges where   fullname like 'NW Norwich St' limit 1


"NW Norwich St";-122.837109;45.537746;"MUL

Re: Σχετ: postgis

Stephen Mather — 2013-05-17T18:14:29

That said, there is value to implementing dependency-free routing algorithms in the core of PostGIS, at least simpler stuff anyway.  I have dijkstra on my todo for PostGIS, but haven't gotten started on it yet.

Best,
Steve



On May 17, 2013, at 11:00 AM, Stephen Woodbridge <woodbri< at >swoodbridge.com> wrote:

Re: Σχετ: postgis

Stephen Woodbridge — 2013-05-17T15:00:54


This is already implemented in pgRouting, look in branch sew-devel-2_0 
which is our 2.0 development branch.

https://github.com/pgRouting/pgrouting/tree/sew-devel-2_0

-Steve

On 5/17/2013 10:31 AM, Adam Eskreis wrote:

Re: Σχετ: postgis

Adam Eskreis — 2013-05-17T14:31:57

You can implement any functions you want using stored procedures with
plpsql.  Alternatively, you can write functions in C and bind them to
postgis.

plpgsql guide: http://www.postgresql.org/docs/9.1/static/plpgsql.html
c functions guide: http://www.postgresql.org/docs/9.1/static/xfunc-c.html

best of luck.

-Adam


On Fri, May 17, 2013 at 5:07 AM, Tina Musa <timuso< at >yahoo.gr> wrote:

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Re: Σχετ: Yen's algorithm

Stephen Woodbridge — 2013-05-17T13:24:01

This is already implemented in pgRouting, look in branch sew-devel-2_0 
which is our 2.0 development branch.

https://github.com/pgRouting/pgrouting/tree/sew-devel-2_0

-Steve

Σχετ: Yen's algorithm

Elena Olivares — 2013-05-17T13:00:57


hello,



i am a student and i need help with postgis.
i want to implement a algorithm (Yen's algorithm computes  K-shortestpaths).
if can somebody help me ???

 thank you in avdance_______________________________________________
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Σχετ: postgis

Tina Musa — 2013-05-17T09:07:17

hello,



i am a student and i need help with postgis.
i want to implement a algorithm (Yen's algorithm computes  K-shortestpaths).
if can somebody help me ???

 thank you in avdance_______________________________________________
postgis-users mailing list
postgis-users< at >lists.osgeo.org
http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users

Σχετ: postgis

Tina Musa — 2013-05-17T08:13:37

hello,



i am a student and i need help with postgis.
i want to implement a algorithm (Yen's algorithm computes  K-shortestpaths).
if can somebody help me ???

 thank you in avdance_______________________________________________
postgis-users mailing list
postgis-users< at >lists.osgeo.org
http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users

Re: Getting argument of AND must not return a set, when trying to calculate the intersection of a end of a multiline and a polygon

Stephen Woodbridge — 2013-05-17T01:22:57

Dave,

st_dump returns a set.
you might want to use st_geometryN(rt.the_geom, 1) instead.

-Steve

On 5/16/2013 7:05 PM, Dave Potts wrote:

Re: Getting argument of AND must not return a set, when trying to calculate the intersection of a end of a multiline and a polygon

Dave Potts — 2013-05-16T23:23:10

Found a different

  solution select count(*)  from route_table rt ,
avoid_areas av
where av.valid=true and rt.parent_port_id=80360 and
st_intersects(av.geom,((rt.the_geom))) =false

will answer the same question.

but I would still like to known why I get that error

D.

Getting argument of AND must not return a set, when trying to calculate the intersection of a end of a multiline and a polygon

Dave Potts — 2013-05-16T23:05:35

Hi,

I am trying to find the results of an intersection between a multi line 
string and a polygon,  I had assumed that saying something
like

select rt.source, 
av.geom,st_astext(st_startpoint((st_dump((rt.the_geom))).geom)) from 
route_table rt ,
avoid_areas av
where av.valid=true and rt.parent_port_id=80360 and
st_within(av.geom,st_startpoint((st_dump((rt.the_geom))).geom)) =true

might work where rt.the_geom is a multiline  and av.geom is a polygon

but I get the error,
ERROR:  argument of AND must not return a set
LINE 4: st_within(av.geom,st_startpoint((st_dump((rt.the_geom))).geo

any idea what I am doing wrong?

Dave

Re: Google Directions -> PostGIS

James David Smith — 2013-05-16T19:47:16

Haha. Whoops. Yes, here is the link:

http://project-osrm.org/

API details here: https://github.com/DennisOSRM/Project-OSRM/wiki/Server-api

Not quite as many options as the Google Directions API, but still pretty
good.

James


On 16 May 2013 20:39, Brian Wilson <brian< at >wildsong.biz> wrote:

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Re: Google Directions -> PostGIS

Brian Wilson — 2013-05-16T19:39:48

James did you miss posting a link? I am sitting on the edge of my seat!
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Re: Google Directions -> PostGIS

James David Smith — 2013-05-16T18:47:29

Hi there,

I wasn't aware that was against the terms and conditions. Thanks for the
tip.

I've therefore had a look around and found this open source alternative. So
same question as above, but please consider this instead of Google! :-)

Thanks

James


On 16 May 2013 17:05, Travis Kirstine <traviskirstine< at >gmail.com> wrote:

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Re: Fwd: line direction

Stephen Woodbridge — 2013-05-16T16:36:54

How do you define arc direction?
If you had a function:

select getArcDirection(arc);

What would you expect the output to be?

In your image, the arc direction is a function of the labeling algorithm 
in combination with this that of the arc. For example if the label were 
flipped upside down and written along the underside of the line then the 
arc direction symbol would have to be reversed. So we can see that it is 
a function of the label and not just the arc alone.

postgis does not do rendering so it can not define that.

-Steve

On 5/16/2013 11:14 AM, franco base wrote:

Re: Google Directions -> PostGIS

Travis Kirstine — 2013-05-16T16:05:31

I don't think this would be permitted based on Google's terms of service,
for example:

Section 10.1.3 *Restrictions against Data Export or Copying.*

(b) *No Pre-Fetching, Caching, or Storage of Content.* You must not
pre-fetch, cache, or store any Content, except that you may store: (i)
limited amounts of Content for the purpose of improving the performance of
your Maps API Implementation if you do so temporarily (and in no event for
more than 30 calendar days), securely, and in a manner that does not permit
use of the Content outside of the Service; and (ii) any content identifier
or key that the Maps APIs Documentation specifically permits you to store.
For example, you must not use the Content to create an independent database
of "places" or other local listings information.



On 16 May 2013 11:01, James David Smith <james.david.smith< at >gmail.com> wrote:

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