ItOpen - Soluzioni WebGIS Open Source » WebGis

Linux Day 2007 a Cinisello Balsamo, GIS e WebGIS

Alessandro Pasotti — Wed, 31 Oct 2007 20:12:43 +0000

Buona la partecipazione e ottimo il livello dei talk al Linux day 2007 organizzato a Cinisello Balsamo.

Abbiamo partecipato direttamente come associazione GFOSS per l’informatica geografica libera all’incontro sui sistemi informativi territoriali con una presentazione sulle applicazioni di web mapping e sull’interoperabilità dei servizi webgis.

Potete scaricare le slide del mio intervento a questo indirizzo:

Slide linux day 2007

Interessantissime novità anche dal punto di vista della certificazione, da poco, grazie al lavoro di Marina Cabrini e Andrea Giacomelli nonché di diversi membri della comunità GFOSS, è possibile ottenere al certificazione GIS ECDL riconosciuta a livello europeo utilizzando solo software libero. Un altro importante traguardo è stato raggiunto!

Maurizio Napolitano ha presentato l’esperienza Web Valley , una iniziativa decisamente interessante di didattica basata sull’informazione geografica e sul software libero.

Un sincero ringraziamento a tutti i relatori, gli organizzatori e i partecipanti di questa bella giornata.

Arrivederci al Linux Day 2008!

Compressione JS in p.mapper

Alessandro Pasotti — Tue, 23 Oct 2007 16:50:20 +0000

Questa breve nota (disponibile solo in inglese) descrive come migliorare significativamente i tempi di caricamento di p.mapper tramite la compressione dei file JavaScript di questo ottimo client WebGIS.

A restful service for mapfile configuration

Alessandro Pasotti — Fri, 05 Oct 2007 07:15:00 +0000

Recently, we’ve been actively working on a restful mapfile configuration service.

The advantages of such a system are those of typical webservice:

fully decoupled from the GUI, the GUI could be written in any language that talks REST
plain text mapfiles as the storage system

The service is being written in PHP and the RESTFUL part is managed with PHP Tonic library.

A few examples of typical URLs:

GET http://www.mymaps.com/maps – retrieve a list of mapfiles
POST http://www.mymaps.com/maps – creates a new mapfile with the JSON data passed on post
GET http://www.mymaps.com/maps/my_first_map.json – retrieve the map data as JSON
GET http://www.mymaps.com/maps/my_first_map.xml – retrieve the map data as XML
GET http://www.mymaps.com/maps/my_first_map.map – retrieve the map data as plain text mapfile
PUT http://www.mymaps.com/maps/my_first_map.json – alter the map with JSON data
PUT http://www.mymaps.com/maps/my_first_map.xml – alter the map with XML data
GET http://www.mymaps.com/maps/my_first_map.xml/layers – retrieve the map layers as XML
GET http://www.mymaps.com/maps/my_first_map.xml/layers/my_first_layer – retrieve the map layer data as XML

Rilasciato MapServer 5.0

Alessandro Pasotti — Wed, 19 Sep 2007 09:34:51 +0000

Una qualità di rendering senza pari

Il nuovo motore di rendering AGG permette di produrre immagini con una resa grafica eccezionale e un antialiasing perfetto.

Le due immagini che seguono sono state generate rispettivamente da MapServer 5 e da MapServer 4:

Per saperne di più, date un’occhiata alle note di rilascio.

Per una guida alla migrazione dalle precedenti versioni, fate riferimento a MapServer 5.0 migration guide.

Back to MapStorer

Alessandro Pasotti — Sun, 19 Aug 2007 17:15:56 +0000

This time, I’ve been asked by the original authors to implement the long awaited mapfile import function. Because of me being the mind and the arm behind the new plugin system, I was the natural choice for the import plugin writing.

Talking about this import plugin, it is now almost complete in its first step, mapfile parsing, while I’m in the process of writing the persistance layer. After a few unsuccessfull tests, I decided not ot use php_mapscript for mapfile parsing, both direct import into a map object and the tokenizer had too many drawbacks, so I went for writing another regular expression parser again.

We discussed several times about how to make MapStorer code more maintainable, the actual code is a real mess, no structure, no patterns (not even a simple front controller), no functions!!! A maintainance nightmare. Finally, after the MDB2 DB abstraction layer I introduced a few months ago, we decided to implement an ORM (Object Relational Mapping). We decided to use PEAR’s DB_DataObject since it plays well with other PEAR packages and it’s very well documented and maintained. After a few troubles with the differences between MySQL and PostgreSQL versions, I’ve managed to implement this ORM almost completely, as usual I wrote several unit tests for the new code: I felt in love with test-driven programming long ago and never turned back.

Un ponte tra KML e mapserver

Alessandro Pasotti — Mon, 09 Jul 2007 16:41:47 +0000

L’idea che mi è venuta spontaneamente è stata quella di scrivere un connettore tra il motore di MapServer che utilizzo per tutti i miei progetti WebGIS e Google Earth, il visualizzatore gratuito di mappe in 3D.

Il formato dati usato da Google Earth (KML) non è supportato al momento da MapServer, che invece supporta lo standard OGC denominato GML.

Sembra che il supporto al formato KML arriverà anche in MapServer, ma per ora non è dato di sapere quando e se sarà rilasciato.

Il formato KML consente inoltre di personalizzare parecchio la presentazione del dato, sia vettoriale che raster e quindi non anche se MapServer supportasse l’output vettoriale KML direttamente, rimarrebbero da risolvere numerosi problemi (primo tra tutti come servire le immagini raster) prima di avere un prodotto veramente utilizzabile.

Scopri i dettagli >>

A script to build the latest mapserver webgis from sources

Alessandro Pasotti — Tue, 24 Apr 2007 07:48:31 +0000

The goal is to have latest versions of mapserver and its main dependencies.

The script will build:

GDAL
PROJ
GEOS
MAPSERVER

How it works

First, all the libraries and mapserver will be downloaded from their official websites, then tey will be uncompressed and extracted on your disk, then they will be configured, built and installed one by one.

Important note: after copying and pasting the script from this page to your PC, you will have to change “ and ″ in ” in the script.

Note that you don’t have to run the script as root, run it as a normal user, you will be prompted for a password when needed. If your distribution doesn’t use the “sudo” system, just change all “sudo” commands in the script into “su -c “.

Prerequisites

Building from sources means you already have installed the compiler, its tools and the header files of all the main shared libraries (zlib etc.) and have a working toolchain for compilation from sources.

This was tested on Linux KUbuntu, Ubuntu server and Debian.

Configuration

After copying the script on the disk and making it executable, you should open it with an editor and change some configuration variables.

More detailed instructions are in the script comments.

If something goes wrong

First uncomment WGET in the code if you don’t want to download all files again, then check your paths and those configured or hardcoded in the script.

Chek also the parameters passed to the “configure” commands in the script, maybe you don’t need all those options.

Code

# Where to install: usually /usr or /usr/local PREFIX=/usr


# Directory of PHP binary libs, in my case, was /usr/lib/php5/20051025/

PHPLIBDIR=/usr/lib/php5/20051025/
# Uncomment for a debug build of gdal library

#DEBUG_GDAL=1
# Activate download (deactivate if you have still downloaded)

WGET=1
# Libraries to fetch, configure, build and install

# Adjust versions according to your needs

GEOS="geos-3.0.0rc4"

GDAL="gdal-1.4.1"

PROJ="proj-4.5.0"

MAPSERVER="mapserver-4.10.1"

# Uncomment if you still have postgresql installed and want

# to build postgis, adjust paths in the last code block of this file

#POSTGIS="postgis-1.2.1"
if [ $GEOS ]; then

if [ $WGET = 1 && ! -f "$GEOS.tar.bz2" ]; then

wget http://geos.refractions.net/$GEOS.tar.bz2

tar -xjf $GEOS.tar.bz2

fi
cd $GEOS

./configure --prefix=$PREFIX

make clean

make

sudo make install
cd ..

fi
if [ $GDAL ]; then

if [ $WGET = 1 ]; then

wget http://download.osgeo.org/gdal/$GDAL.tar.gz

tar -xzf $GDAL.tar.gz

fi
cd $GDAL

if [ $DEBUG_GDAL ]; then

export CFG=debug

fi

./configure --prefix=$PREFIX --with-mysql

make clean

make

sudo make install

cd ..

fi
if [ $PROJ ]; then

if [ $WGET = 1 ]; then

wget ftp://ftp.remotesensing.org/proj/$PROJ.tar.gz

tar -xzf $PROJ.tar.gz

fi
cd $PROJ

./configure --prefix=$PREFIX

make clean

make

sudo make install

sudo cp $PREFIX/include/proj_api.h $PREFIX/lib

cd ..

fi
if [ $MAPSERVER ]; then

if [ $WGET = 1 ]; then

wget http://cvs.gis.umn.edu/dist/$MAPSERVER.tar.gz

tar -xzf $MAPSERVER.tar.gz

fi
cd $MAPSERVER

./configure \

--with-wfs \

--with-wfsclient \

--with-wmsclient \

--with-proj=$PREFIX/lib \

--with-geos=$PREFIX/bin/geos-config \

--with-gdal=$PREFIX/bin/gdal-config \

--with-ogr=$PREFIX/bin/gdal-config \

--with-php=/usr/include/php5 \

--with-mygis=yes \

--with-postgis \

--with-httpd=/usr/sbin/apache2 \

--prefix=$PREFIX

make clean

make

sudo cp mapserv /usr/lib/cgi-bin/

sudo cp shp2img $PREFIX

sudo cp shptree $PREFIX

sudo cp tile4ms $PREFIX

sudo cp mapscript/php3/php_mapscript.so $PHPLIBDIR

cd ..

fi
if [ $POSTGIS ]; then

if [ $WGET = 1 && ! -f "$POSTGIS.tar.gz" ]; then

wget http://www.postgis.org/download/$POSTGIS.tar.gz

tar -xzf $POSTGIS.tar.gz

fi
cd $POSTGIS

./configure --prefix=$PREFIX/lib/postgresql/8.1/

make clean

make

sudo make install

cd ..

fi

Il nuovo WEBGis dei sentieri del Verbano Cusio Ossola

Alessandro Pasotti — Fri, 20 Apr 2007 08:46:30 +0000

Il progetto

Il progetto, finanziato tramite un programma INTERREG dell’Unione Europea comprende partner Italiani e Svizzeri per quanto riguarda il cantone Ticino e Vallese.

La cartografia si basa sul rilievo della rete sentieristica tramite GPS e sul catasto sentieri del Club Alpino Italiano.

Il database contiene diverse centinaia di itinerari, escursionistici e alpinistici, centinaia di punti di interesse con le relative schede di dettaglio e un gran numero di strutture ricettive escursionistiche (rifugi e bivacchi) e non.

Le tecnologie utilizzate

Abbiamo realizzato il portale utilizzando il top dei prodotti open source disponibili per la pubblicazione su web della cartografia digitale:

Mapserver
POSTGIS
p.mapper
PHP5

Il sito web

Il sito è raggiungibile all’indirizzo www.vcoapiedi.net

Producing tiles from a GEOTIFF Raster with PHP and gdal

Alessandro Pasotti — Mon, 19 Mar 2007 13:32:15 +0000

This short script convert a single GEOTIFF raster file in smaller tiles, suitable for tileindex in MapServer.

Prerequisites

The script calls external programs such as gdalinfo and gdal_translate, hence you will need a working installation of gdal library and all the utilities that come with the library.

Overviews

If you also want to produce overviews at a given scale, comment out the exit line and add you desired scales to the “scales” array.

if($argc != 3){ die("Usage: {$argv[0]} filename desired_square_dimension_in_map_units\n"); }


$file_name = $argv[1];

$square    = $argv[2];
$info = `gdalinfo $file_name`;
foreach(split("\n", $info) as $i){

    if(strpos($i, 'Lower Left') !== false){

        preg_match_all('/\d+\.\d+/', $i, $res);

        $ll_x = $res[0][0];

        $ll_y = $res[0][1];

    }

    if(strpos($i, 'Upper Right') !== false){

        preg_match_all('/\d+\.\d+/', $i, $res);

        $ur_x = $res[0][0];

        $ur_y = $res[0][1];

    }

}
// Extent

$x_ext = $ur_x - $ll_x;

$y_ext = $ur_y - $ll_y;
// Fit square

$iter_x = floor($x_ext / $square);

$iter_y = floor($y_ext / $square);
$square_x = floor($x_ext / $iter_x);

$square_y = floor($y_ext / $iter_y);
// Iter

$iter_x = floor($x_ext / $square_x);

$iter_y = floor($y_ext / $square_y);
$tiles_number = $iter_x * $iter_y;
print "Coords ($ll_x, $ll_y) - ($ur_x, $ur_y)\n";

print "Ext  ($x_ext) - ($y_ext)\n";

print "Producing $iter_x x $iter_y = $tiles_number tiles for $square_x x $square_y\n";
for($ix = 0 ; $ix < $iter_x; $ix++){

    $tile_llx = $ix * $square_x + $ll_x;

    $tile_urx = $tile_llx + $square_x;

    for($iy = 0 ; $iy < $iter_y; $iy++){

        $tile_lly = $iy * $square_y + $ll_y;

        $tile_ury = $tile_lly + $square_y;

        print "Tiling \t($ix, $iy)\t($tile_llx, $tile_lly) - ($tile_urx, $tile_ury) \n";

        // Tile filename

        //$tilename = "$tile_llx-$tile_lly-$tile_urx-$tile_ury.tif"

        // Proj wants UL LR

        $tilename = "$tile_llx-$tile_ury-$tile_urx-$tile_lly.tif";

        `gdal_translate -of GTiff -projwin $tile_llx $tile_ury $tile_urx $tile_lly $file_name $tilename`;

    }

}
// Remove exit and define scales if you want to produce overviews at defined scales

exit();
// Build overviews

$scales = array(1000000, 500000);
// Conversion

$dpi = 72;

// Screen resolution in meters: pixel/meter of screen

$dpm = 0.0254 / $dpi;
$scale_pix = array();

foreach($scales as $s){

    $scale_pix[] = $s * $dpm;

}
//var_dump($scale_pix);

$i = 0;

foreach($scale_pix as $sp){

    $ovfile = 'OVV-' . $scales[$i++] . '-' . floor($sp) .'.tif';

    `gdalwarp -of GTiff -rc -tr  $sp $sp $file_name $ovfile`;

}

Masptorer – P.mapper webgis plugin released

Alessandro Pasotti — Wed, 07 Mar 2007 09:05:28 +0000

Although the current version of .pmapper use different configuration files, it
should not be too difficult to update the plugin for the current p.mapper
version.

Features

This plugin adds the following features:

Pmapper configuration
Automatic reference map

This plugin handles p.mapper 2.1.1 .ini configuration file. It also adds a
trigger on mapstorer export mapfile function that will keep p.mapper .ini
file and mapfile in sync.

Do not forget to export the mapfile and restart p.mapper to activate the new
configuration.

Configuration files for p.mapper are saved on a mapfile base: the mapfile name
({MAPFILE_NAME}) is used as a base for creating configuration directory
(called “project” in p.mapper slang).

The p.mapper .ini file will be saved as config_{MAPFILE_NAME}.ini and the
custom js and php files are saved in config/{MAPFILE_NAME}/ directory. These
directories must be writeable by the web server user.

Warnings

Warning: switching off layer queryability could provoke loss of data in case
you have set up a “real” template file path for the layer, in such case, the
content of the TEMPLATE field will be cancelled.

Warning: enabling automatic reference map creation, will overwrite existing
reference maps whenever you update map object record.

Warning: this plugin is ALPHA quality code (works for me), and is not
supported.

Download

Find it in the latest MapStorer SVN: www.mapstorer.org