How to display and use data from Sigeom's web mapping service
Caroline Thorn et Luc Charbonneau
Ministère des Ressources naturelles
In November 2012, Géologie Québec announced the arrival of new online Web mapping services (WMS) for Sigeom in an article published in the Québec Mines bulletin (Thorn, 2012). To follow up on that article, here is a more technical explanation on how to integrate the data into your geographic information system (GIS).
Web mapping services
A WMS is a standardized service that displays georeferenced data and geographic maps in a GIS. A WMS server sends the GIS-requested image over the Internet. The GIS (or the webpage) overlays all the images and produces the desired map.
With a WMS, the user does not have to worry about format, coordinate system, or storing the spatial data. The user has access to the most recent and accurate data by virtue of the access to the authentic data source. A WMS allows the user to complete an existing data set, facilitates the gathering of new data, or simply displays (visualizes) the data. Another functionality allows additional information to be obtained for each of the geographic elements imported into the map.
Despite the many advantages of using a WMS, there are some limitations that should be taken into account. For example, a WMS will not allow the user to perform a data search or download data.
Accessing the data
A WMS is integrated into a project through an intermediary URL address that contains parameters related to the requested data, coordinate system, area of interest, etc. Today, most geographic information systems have a function that allows the user to add georeferenced data using a Web mapping service.
To learn more about how to integrate Sigeom data into your projects using Web mapping services, download the Sigeom Web services user’s guide (PDF format). It provides a step-by-step description of the procedure for several types of software, open-source or proprietary, including Quantum GIS, OpenJUMP, uDIG and ArcGIS.