Last week (22nd of November) we looked at web services (WMS / WFS / WCS) to get our hands on spatial data. Online services can be found using search engines (Google or dedicated portals like GEOSS - see handout - access geodata - v.2019_Oct19 ). Even the Open Geospatial Consortium (OGC) has a dedicated webpage on how to find/access these services, which is a hot topic. https://www.opengeospatial.org/blog/2034

These services allow a live link with online spatial data. They depend on an active company/agency, on a well-maintained server, on fast internet connection etc... so they are not always easy to deal with.

In class we accessed services from the Italian National Geoportal (refer to the PDF  handout - access geodata - v.2019_Oct19 ) but their server was very slow - we then tried the GEOSS portal, to mine for data. We had a hands-on experience of how difficult it is to find good data.

To test if you understood how to deal with these services do the following in-class assignment: - If you do not remember how to load data from web services , from last week's lecture, go to the online tutorial on WMS (same principle applies to WFS and WCS) - Working with WMS Data

  • go to the home page of the Regione Veneto Geographic portal - https://idt2.regione.veneto.it/
  • in that page at the bottom, you will find a couple of we addresses (URLs)  related to these services - it is in Italian, but you are smart enough to understand which string is a web address (URL) - the first (https://idt2-geoserver.regione.veneto.it/geoserver/ows)  use this URL for both WFS and WMS!
  • use WMS and WFS URLs to load WMS and WFS data related to Nitrogen production from agricultural practices in each of Veneto's municipalities - the coded string to look for is "c1016281_carichiazotoagr".
  • For WFS, export and download the layer in your computer, add it to QGIS as layer, and apply a  theme from white to red for the SAU_HA column, which is the Used Agricultural Area (Superficie Agricola Utilizzata - SAU) - if you do not remember how, check online tutorial Basic Vector Styling (QGIS3)
  • Hand in two screenshots like below, which are respectively the vector layer and the WMS layer (with or without Google Satellite layer) Assignment 2 (in class assignment 29th November) hand-in   or send to francesco.pirotti@unipd.it



Ultime modifiche: venerdì, 27 dicembre 2019, 16:20