Topic 9

Geospatial technologies help us create content that can be changed and visualized interactively. Here there is the opportunity to get started with web mapping. 

Web mapping is done using cloud-based technologies – similar to Facebook, Flickr, Google Drive, or Dropbox. Web mapping use logic similar to standard and professional GIS packages – as data georeferenced and organized in layers, with the possibility to query and filter them. In Web mapping applications you can organize pre-existing maps, geographical databases, satellite imagery, upload your own data (i.e., GPS tracks of your climb in the mountains or the pin-pointed clubs of your summer vacation). Also web mapping applications host tools and functions to measure things and to do some spatial analysis.

Here in this exercise we will try some hands-on experience viewing existing maps – done by users putting together data from different sources – and making your own maps and doing spatial analysis.

The web mapping used here is Esri’s (http:// www.esri.com) cloud-based GIS “ArcGIS Online” while other platforms are Geocommons (http://geocommons.org) and GIS Cloud (http://www.giscloud.com).

Start working with the ArcGIS map “World Map. Cities, Transport, Countries, Economic indicators” available at: http://www.arcgis.com/home/webmap/viewer.html?webmap=42c674db5a36448cbe42be9a55a4788d

The organization of a web mapping application is a map – on the centre – a set of map layers on the left (a ‘legend’) and some tools on top of the map and other in drop-down lists on the layers’ side.

 Here in this map you find point, line and area features, as well as a background resembling the physical map of the world. Point, line and area features are referred to cities, transport infrastructure, population and GDP.

1) Start familiarizing with the tools. Switch on and off layers, try to move them on top of each other and see what features can be visualized at the same time. Also use the mouse / pointer to pan (=move on the map) and the sidebar (or double touch) to zoom-in and out.

Try to familiarize with the data and the software. Recall some data by clicking /double-clicking on the map. What happens? What data are you querying? How are they organized (=what kind of information are stored)?

 2) now zoom into a region of the world and try analysing it more in depth. Try changing the colours of the area layers (population density; GDP) by working on the legend on your left side of the screen. What happens? What happens if you change the size of the dots representing the world cities? How would you describe the pattern of world population density?

After playing with tools and functions, try think about the map and the different layers loaded. At your convenience turn on and off layers to better examine data. Then try answering the following questions:

• What can you say about the spatial distribution of largest cities?
• How do you relate the distribution of cities and world population density?
• Are transport networks evenly distributed? Where can you spot the higher concentrations?
• GDP data are available at country’s level and not at a finer scale. Recalling your knowledge and what you studied how would you expect GDP distribute within a country? What could it be the relationship with cities and population density distribution?

3) now try to add data to your map. You have to sign in to make changes and save a map (publicly viewable) Search a layer according to a criterion (i.e., transport;  unemployment;  development, etc.). What are some of the data like? Who produced them? What is the level of detail you can get?

Now open also the Geocommons  project “World major urban and GDP” available at http://geocommons.com/maps/201491 and observe it.

4)  What are the differences between the two web mapping applications?  Are there the same data or they differ? If so, what are the differences?