Through the GeoBase portal, users with an interest in the field of geomatics have access to quality geospatial information at no cost and with unrestricted use. GeoBase.. building a common ground. That’s the catch phrase that greets visitors to this latest effort of the Canadian Government to make geospatial data accessible to the public via the web. Actually, its not just the Canadian Government, but rather, a joint effort of the Federal Government (NRCan), Provincial, and Territorial agencies – in total, more than 30 cooperating agencies are involved in the initiative… well done! Officially launched on November 19, 2003 (coincidentally, GIS Day as well!), the official mandate is as follows "… to ensure the provision of, and access to, a common, up-to-date and maintained base of quality geospatial data for all of Canada." The portal boasts that it is a response to the overwhelming request for free spatial data.
So what kind of data is available? At first glance, it appears that available themes include road networks, landform/topography, place names, administrative boundaries, geodetic network and satellite imagery.
Regional scale data is available between 1:10 000 to 1:250 000 scales while National datasets are 1:1 000 000 and smaller.
I opted to jump right in and attempt to access the data. A graphic search tool was presented to me and I simply selected a data theme/Product (9 options were presented) and a geographic range. I selected Elevation data at 1:250,000 scale (1:50,000 was another option)
A map GUI is used to access/search for data
Map Grid displays available data – click image to view next screen showing 1:250K grid
I finally selected shet O92B (Victoria). The data format was described as CDED modified USGS format [apparently this data can be translated by most USGS SDTS DEM translators]. Projection was specified to be Lat/Long and I had the choice to download as English or French product.. I selected English as my francais is a bit rusty!
The final step was to click the "Delivery" option ("Download" would have made more sense to me), however, this leads me to believe that additional options for delivery may be coming in the future. Prior to getting the requested data I was presented with an "unrestricted data use" license. I click Agree and I am then presented with an email delivery dialog box requesting that I submit an email address where I would like to receive delivery information. A message tells me "You will receive an email once all the datasets you selected are processed". Note, I could have requested multiple datasets rather than one file, hence the need to comipile the request. This is also a good way to keep tabs on data hounds that seek out and grab any data they can find.
Going back to my email client, I notice a message from Geobase. It reads, "The file(s) you have ordered are now available on our FTP site in a directory in your name (see the links at the end of this email). These files will be available for FTP download for the next five (5) days." In addition to the link to their ftp site, I am also provided with a direct link to the ZIP file. The compressed file is 881 KB in size and it also come with Metadata that conforms to the FGDC Content Standard for Digital Geospatial Metadata.
So now what? I decide to view the data using a freely available data viewer called DLGV32 Pro. For those of you not familiar with it, the product supports most common data formats and specialises in USGS formated data. See http://mcmcweb.er.usgs.gov/drc/dlgv32pro/ (8 MB download)
After a quick download and a painless install, I fire up my free DLGV32 Pro (aka. Global Mapper) and open the .DEM file – see below (click on image to enlarge) – Very nice!
The Geobase portal appears to be a very attractive and useful resource. Users will likely be searching for higher resolution data, something that’s always been unavailable for free in Canada. If you plan on finding 1:20,000 or even 1:50,000 digital topo data you’ll be out of luck. The site appears to be repackaging what was previously available from geogratis but given the number of stakeholders, I expect alot more data to be made available in the future. Entirely web [GUI] driven, users won’t find pointers to FTP sites like they may have on other Canadian geospatial data portals, however, they will find a clean, simple to use, and fast map server.
The GeoBase Portal, operated by Natural Resources Canada, is a federal, provincial and territorial government initiative that is overseen by the Canadian Council on Geomatics (CCOG). It will ensure the provision of, and access to, a common, up-to-date and maintained base of quality geospatial data for all of Canada. Through the GeoBase portal, users with an interest in the field of geomatics have access to quality geospatial information at no cost and with unrestricted use. To access GeoBase, visit www.geobase.ca.