Geodata de filippi riccardo defilippi@fbk.eu source
For what do we need GIS? GIS - workflow Users Infrastructure Vector Raster Data Acquisition Space Algorithm Statistics System Definition Data Modelling Processing & Analysis Presentation Spatial Reference Scale (spatial, temporal)
From geoid to a map geoid ellipsoid projection (Dylan Prentiss, 2009) ESPG: PROJCS["ETRS89 / UTM zone 32N", GEOGCS["ETRS89", DATUM["D_ETRS_1989", SPHEROID["GRS_1980",6378137,298.257222101]], PRIMEM["Greenwich",0], UNIT["Degree",0.017453292519943295]], PROJECTION["Transverse_Mercator"], PARAMETER["latitude_of_origin",0], PARAMETER["central_meridian",9], PARAMETER["scale_factor",0.9996], PARAMETER["false_easting",500000], PARAMETER["false_northing",0], UNIT["Meter",1]] y location region x
EPSG European Petroleum Survey Group 3000 codes which identify reference systems Database with codes, elipsoids definition, datum positioning, pojections ect. Open Geo Consortium refer to codes as Epsg:<code> Urn:ogc:def:crs:EPSG<codice> EPSG Trentino UTM_WGS84: EPSG <32632>
Spatial representation From reality to spatial model (Zeiler, 1999)
Objective: Interaction: SM (1) Modelling terrain surface elevation within a digital map Decide, which of the below representation methods you would prefer Argue, why you consider it to be suited the best one Contour lines (Vectors) Surface grid (Raster) Triangulated Irregular Network (TIN) Zeiler (1999)
Spatial Models Geographically referenced data (Geo-referenced) All located in a reference system 2 d, 3d, 4d etc All have a geometry and attributes Y. X
Vector representation: Geometry Features Points Polylines Polygons Recording of locations Two-dimensional [x,y] coordinates Series of ordered [x,y] coordinates that define line segments Series of [x,y] coordinates defining line segments that enclose an area Zeiler (1999)
Vector representation: Attributes Feature-attributes: Zeiler (1999)
Vector representation: Attributes (2) Numeric attributes Classified attributes Type attributes Descriptive attributes Zeiler (1999)
Raster representation: Geometry Zeiler (1999)
Raster representation: Geometry (2) McCoy et al. (2002) Coordinate space of raster datasets
Raster representation: Data types Thematic data - Spatially continuous data - Spatially discrete data z z x,y Example: Terrain elevation x,y Example: Land-use categories
Picture/Image data - True color (RGB) or false color Raster representation: Data types (2)
(Re-)Classification Raster representation: Data types (3) Discrete phenomena Continuous phenomena Discrete raster data Zeiler (1999)
Satellite imagery Black and white Greyscale Colour Raster representation: Data sources Geo-rectified Geo-referenced www.swisstopo.ch
Converted Data Feature datasets (vector) TIN datasets Raster representation: Data sources (3) Zeiler (1999) McCoy et al. (2002)
Raster representation: Feature extraction Applications
Raster representation: Applications (2) Land-use scenario Terrain analysis Environmental analysis Zeiler (1999)
Geodata via WEB Geospatial Web Server Vector and Raster data Open Geo Consortium Standards WMS, WFS, WCS.. Server Requests Server Response
Types of Geospatial Web Services Web based services with a focus on geospatial information 1. Data Discovery: Provide search and discovery to geospatial data and services 2. Data Visualization: Provide visualization images of the actual geospatial data 3. Data Access :Provides access to the actual geospatial data http://www.gsdi.org
PNG / JPG XML / URL GeoTIFF XML / URL XML (GML) XML / URL Raster maps SpatialDB Interpolation algorithms Vector data Statistical data Temp CC scenarios SOS Ensambles (regional) WORLDCLIM (global) Real time observation Apache / Tomcat Geoserver WMS WCS WFS-T Map generation Read Raster Read/Edit Vector GeoExt OpenLayer ExtJS Nasa World Wind
Open Geo Consortium OGC The Open Geospatial Consortium, Inc. (OGC) is a non-profit, international, voluntary consensus standards organization that is leading the development of standards for geospatial and location based services. http://www.opengeospatial.org/.org
OGC in short WMS (Web Map Service) + SLD (Styled Layer Descriptor) Creating maps from raw data, query, legends WFS (Web Feature Service) Describe, deliver and modify vector data WCS (Web Coverage Service) Describe and serve raster data WPS (Web Processing Service) execute spatial analysis
Web Map Service WMS WMS mette a disposizione un catalogo di strati per creare mappe, che possono essere fornite: in un insieme di formati di uscita (tipicamente raster, come PNG, GIF, JPEG) in un insieme di proiezioni cartografiche ciascuno con uno o piu stili predefiniti E' possibile interrogare la mappa in un punto OpenGeo
---------- ---------- ---------- --------- ---------- ---------- --------- ---------- Stili (SLD) Catalogo layer, stili, funzionalità supportate Dati vettoriali e raster GeoServer WMS GetCapabilities GetMap GetFeatureInfo GetLegendGraphics Disegno mappa PNG, GIF, JPEG, GeoTiff, KML, SVG, PDF, GeoRSS,... Interrogazione dati HTML, GML2, TXT ---------- ---------- ---------- --------- ---------- ---------- --------- ---------- Template (personalizzazione output) Legenda PNG, GIF WMS 1.1.1 OpenGeo
WMS GetCapabilities La risposta a questa chiamata e un documento XML, di norma piuttosto lungo La risposta elenca Metadati sul server (titolo, gestore, ecc.) Informazioni sulle chiamate supportate (quali formati di uscita ecc.) L'elenco dei layer (titolo, abstract, sist. rif., area coperta, stili) http://maps.geog.umd.edu/firms/wms.htm OpenGeo
WMS Get Map Permette di ottenere una mappa specificando nella chiamata: Un elenco di layer da visualizzare Un elenco di stili (può essere vuoto per adottare gli stili di defalt) L'area da visualizzare La dimensione dell'immagine Il formato di immagine restituito Il colore di sfondo, l'eventuale trasparenza dell'immagine http://maps.geog.umd.edu/firms/wms.htm OpenGeo
WMS GetFeatureInfo Chiede al server informazioni Cosa c'e nella mappa al pixel x,y? L'output puo essere fornito in vari formati: HTML testo GML (Geographic Markup Language, una forma di XML) OpenGeo
Web Feature Service WFS Protocollo per l'accesso e la modifica di Feature geografiche Al contrario di WMS, si lavora a livello di dato, non di rappresentazione. WFS opera a livello di codice sorgente dell'informazione geografica. Gli oggetti territoriali di WFS si chiamano Feature: identificativo (FID, Feature ID), una o più geometrie (vettoriali), eventuali attributi
Profili WFS Basic sola lettura GetCapabilities DescribeFeature GetFeature Transactional Lettura e scrittura Transaction GetFeatureWithLock Lock
Get Capabilities WMS Strutturalmente simile alla GetCapabilities di WMS, ovvero: informazioni generali sul server chiamate e relativi formati di uscita elenco layer Ma questa volta si lavora a livello di dato grezzo, non ci sono stili
DescribeFeatureType Ritorna la struttura delle Feature in forma di XML schema
<FeatureType> <Name>tiger:poly_landmarks</Name> <Title>Manhattan (NY) landmarks</title> <Abstract>Manhattan landmarks, identifies water, lakes, parks, interesting buildilngs </Abstract> <Keywords> DS_poly_landmarks, poly_landmarks </Keywords> <SRS>EPSG:4326</SRS> <LatLongBoundingBox minx="-74.047185" miny="40.679648" maxx="-73.90782" maxy="40.882078" /> </FeatureType> <FeatureType> <Name>tiger:poi</Name> <Title>Manhattan (NY) points of interset</title> <Abstract>Points of intereset, Manhattan, New York. One of the attributes contains the name of a file with a picture of the point of interest.</abstract> <Keywords> poi, DS_poi </Keywords> <SRS>EPSG:4326</SRS> <LatLongBoundingBox minx="-74.0118315772888" miny="40.70754683896324" maxx="-74.00857344353275" maxy="40.711945649065406" />
Get feature Estrae le Feature di uno o più FeatureType: scelta degli attributi filtro per decidere quali Feature selezionare http://ckan.net http://demo.geomatys.com/cstl-trunk/ws/wfs? http://wiki.osgeo.org/wiki/public_geospatial_data_ Project
WFS filter <wfs:getfeature service="wfs" version="1.0.0" outputformat="gml2" xmlns:topp="http://www.openplans.org/topp" xmlns:wfs="http://www.opengis.net/wfs" xmlns:ogc="http://www.opengis.net/ogc" xmlns:gml="http://www.opengis.net/gml" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance" xsi:schemalocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.0.0/wfs-basic.xsd"> <wfs:query typename="topp:states"> <ogc:propertyname>state_name</ogc:propertyname> <ogc:propertyname>land_km</ogc:propertyname> <ogc:propertyname>the_geom</ogc:propertyname> <ogc:filter> <ogc:propertyisbetween> <ogc:propertyname>land_km</ogc:propertyname> <ogc:lowerboundary> <ogc:literal>140000</ogc:literal> </ogc:lowerboundary> <ogc:upperboundary> <ogc:literal>150000</ogc:literal> </ogc:upperboundary> </ogc:propertyisbetween> </ogc:filter> </wfs:query> </wfs:getfeature> < 150000 ovvero: 140000 < LAND_KM