blank image

Terence Maru terence at WAIROADC.GOVT.NZ
Mon Sep 10 20:57:25 EDT 2007


Hi All, I have got it to work, first off the extent was wrong, I found
this by executing the sql "select extent(the_geom) from parcels" in my
postgis database.  The last thing to address was the setting
$parcelLayer->set("status", MS_DEFAULT);  Which I assume is MS_OFF, I
changed this setting to MS_ON and it worked.  Thanks everyone for
helping me work through this problem.  

bm
> ______________________________________________ 
> From: 	Terence Maru  
> Sent:	Tuesday, 11 September 2007 11:17 a.m.
> To:	MAPSERVER-USERS at LISTS.UMN.EDU
> Subject:	RE: [UMN_MAPSERVER-USERS] blank image
> 
> 
> Hi Matt, thanks for the explanation. 
> 
> The projection for the output map is in (NZ Mapping Grid = 27200) this
> is set using mapscript - is this correct?
> $map = ms_newMapObj("");
> $map->setProjection('init=epsg:27200');
> 
> The projection for the layer is not set using mapscript.  The layer
> information comes from a postgis database.  When I imported the data
> into the postgres/postgis database I set the srid.  This is validated
> from describing the parcels table - Is this correct, should I be using
> mapscript to set the projection in the map file for this layer?
> Check constraints:
>     "enforce_dims_the_geom" CHECK (ndims(the_geom) = 2)
>     "enforce_geotype_the_geom" CHECK (geometrytype(the_geom) =
> 'MULTIPOLYGON'::text OR the_geom IS NULL)
>     "enforce_srid_the_geom" CHECK (srid(the_geom) = 27200)
> 
> To find the correct extents from the postgis database I used this sql
> statement - Is this correct
> select extent(the_geom) from parcels;
> 
>                    extent
> ---------------------------------------------
>  BOX(2825539.75 6199758.5,2942387.5 6283728)
> (1 row)
> 
> I then set the extent in the map file using mapscript
> $map->setExtent(2825539.75, 6199758.5, 2942387.5, 6283728);
> 
> Image was still blank.  I think I will set the projection in the layer
> and see how that goes, any help would be much appreciated.  Thanks in
> advance for the help.
> 
> bm
> 
> 
> -----Original Message-----
> From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU]
> On Behalf Of Matthew Perry
> Sent: Monday, 10 September 2007 2:44 p.m.
> To: MAPSERVER-USERS at LISTS.UMN.EDU
> Subject: Re: [UMN_MAPSERVER-USERS] blank image
> 
> Terence,
> 
> There are three separate issues:
> 
> 1. What projection is your output map in? This is the projection of
> the overall map, presumably the NZ grid.
> 
> 2. What projection is your data in? This is the projection assigned to
> your layer. If different than #1, it must be assigned and the data
> will be reprojected on-the-fly.
> 
> 3. What is the extent in the output map projection? Use this to set
> the map extents. If your output map is in the epsg:27200 projection ,
> then your given extents (-180, -90, 180, 90) are not correct. Those
> are the geographic coordinates (ie longitudes and latitudes) but you
> want to specify the extent in the NZ grid.
> 
> 
> - matt
> 
> On 9/9/07, Terence Maru <terence at wairoadc.govt.nz> wrote:
> >
> >
> >
> > Hi all, I have added a projection to the map object (see attached
> php
> > script).  I have also attached the postgis table describe.  The
> > postgis describe shows that the table "parcels" has a constraint
> check
> > on the_geom
> > (column) that the srid is 27200 (NZ Mapping Grid).  Does this mean
> > that the database has the correct projection?  I have added in the
> > mapscript the line "$map->setProjection('init=epsg:27200');", my
> > understanding is that this sets the correct projection for the map
> > object?  Do I need to set the projection for the layer object too?
> Im
> > still getting a blank image.  I thought it might have something to
> do
> > with the extents if my projections are correct?  Still reasearching
> though.  Thanks in advance.
> >
> > <postgis-start>
> > Indexes:
> >     "parcels_pkey" PRIMARY KEY, btree (gid)
> >     "gist_index" gist (the_geom)
> > Check constraints:
> >     "enforce_dims_the_geom" CHECK (ndims(the_geom) = 2)
> >     "enforce_geotype_the_geom" CHECK (geometrytype(the_geom) =
> > 'MULTIPOLYGON'::text OR the_geom IS NULL)
> >     "enforce_srid_the_geom" CHECK (srid(the_geom) = 27200)
> > </postgis-end> <php_mapscript-start> $map = ms_newMapObj("");
> > //$map->set("debug", MS_TRUE); $map->setSize(600, 300);
> > $map->setExtent(-180, -90, 180, 90);
> >
> > //define path where to creat image
> > $map->web->set("imagepath", "./data/"); $map->web->set("imageurl",
> > "./data/"); $map->web->set("log", "./data/logfile.txt");
> > $map->setProjection('init=epsg:27200');
> >
> > //crate parcel layer, associate it withthe map $parcelLayer =
> > ms_newLayerObj($map); $parcelLayer->set("connectiontype",
> MS_POSTGIS);
> > $parcelLayer->set("name", "parcels layer");
> >
> > $connector = "user=user dbname=dbname host=localhost";
> > $parcelLayer->set("connection", $connector);
> >
> > $sql = "the_geom from parcels";
> > $parcelLayer->set("data", $sql);
> >
> > $parcelLayer->set("status", MS_DEFAULT); $parcelLayer->set("type",
> > MS_LAYER_POLYGON); //$parcelLayer->set("debug", MS_ON);
> >
> > $parcelClass = ms_newClassObj($parcelLayer);
> $parcelClass->set("name",
> > "parcels class");
> >
> > $parcelStyle = ms_newStyleObj($parcelClass);
> > $parcelStyle->color->setRGB( 250, 0, 0);
> > $parcelStyle->outlinecolor->setRGB( 255, 255, 255);
> > //$parcelStyle->set("symbol", 7); $parcelStyle->set("symbolname",
> > "circle"); //$parcelStyle->set("size", 6); $parcelStyle->set("size",
> > 10); </php_mapscript-end>
> >
> > bm
> >
> >
> >
> >
> > -----Original Message-----
> > From: UMN MapServer Users List
> > [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On Behalf Of Gregor Mosheh
> > Sent: Wednesday, 5 September 2007 12:02 p.m.
> > To: MAPSERVER-USERS at LISTS.UMN.EDU
> > Subject: Re: [UMN_MAPSERVER-USERS] blank image
> >
> > Terence Maru wrote:
> > > Hi everyone, I have a problem generating an image from my postgis
> > > database  I have attached my php script.  No errors are returned
> > > when the script is run, just a blank image is returned.  Can
> anyone
> > > see whats wrong with my script?  Cheers
> >
> > This exact same question came up two days ago. 90% of the time, the
> > issue is projections. Ensure that all layers and the output map are
> in
> > the same projection, or else set projection blocks. 90% of the time,
> that fixes it.
> >
> >
> > --
> > Gregor Mosheh / Greg Allensworth
> > System Administrator, HostGIS cartographic development & hosting
> > services http://www.HostGIS.com/
> >
> > "Remember that no one cares if you can back up,
> >   only if you can restore." - AMANDA
> >  ________________________________
> >  This e-mail message has been scanned for viruses by McAfee and the
> > content has been cleared by MailMarshal
> > ________________________________
> >
> 
> 
> --
> Matthew T. Perry
> http://www.perrygeo.net
> 
> "You never change things by fighting the existing reality.
> To change something, build a new model that makes the existing model
> obsolete" - R. Buckminster Fuller
> 
> 

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