GEOG 445 Lab 6 VGI

Goal and Background

This lab is an introduction to VGI, or volunteered geographic information. VGI is a crowdsourcing operation that allows the general public to collect and upload geo-locations and their associated attribute information to a web GIS application. This lab will teach someone how to develop a web GIS VGI application that can be used by the general public to upload geo-locational information for a number of phenomena.

Methods

The first section of this lab addresses the creation of a map document that will later be used to publish services to an online server. In order to set domains for the feature classes, the properties must be edited within the geodatabase for the VGI application. This is when coded value domains can be set, for example a 0 representing a red fire hydrant and a 1 representing a yellow fire hydrant. The VGI application in this lab will display 3 feature classes each with domains including fire hydrants (red or yellow), sidewalks (very good or needs repair) and green spaces (lush or needs fixing). While creating the feature classes, each one can be configured to use the corresponding coded value domain and include user comments during data publication.

In order to make our feature classes cartographically pleasing, we will customize the symbology of each coded value domain. The image below shows how each feature class will appear on the completed VGI application.

After a simple basemap is added, the feature classes are ready to be tested within the map document. For the purposes of the lab, we placed one of each domain onto the basemap as shown below.

Everything looks good so far, so the next step is to connect to ArcGIS server publisher. Once connected, all nonessential layers can be removed from the map document and the VGI features can be shared as a service. Within the service editor, it is crucial to include “Feature Access” as a capability. This is what will allow end users to edit and add data to the application. Once the feature has been published, it can be referenced within a JavaScript code and displayed in the application.

For this lab, we will be editing an existing VGI application instead of creating a new one. The existing application is based in Washington D.C. and was created for the collection of point, line, and polygon hazard features. The first step is to locate the coordinates within the JavaScript code and replace the Washington D.C. coordinates with Eau Claire coordinates. Next, all of the point, line, and polygon feature URLs will be replaced by the URLs for the services that we created on the server. After changing the title to suit this lab, the application is up and running.

The final portion of this lab had each student construct his or her own VGI application. I chose to build an application that mapped out the emergency telephones located on the University of Wisconsin- Eau Claire campus. The end user can specify if each telephone located in a well lit or dark area during night hours, and include any other comments if necessary (up to 80 characters). The only challenge encountered during this portion of the lab was attempting to use an aerial image for a basemap instead of a topographic map. The topographic map works fine but the UWEC campus is not detailed within the basemap and it may be difficult for end-users to find the desired location for their data.