Wednesday, January 22, 2014

A bird’s-eye view of Calgary on June 22, 2013

The City of Calgary has released a highly accurate aerial photograph taken on June 22, 2013 of the areas adjacent to the Bow and Elbow rivers.  The photo is referred to as an orthophoto and was taken by a low-flying aircraft on June 22, between 8 a.m. and 9:30 a.m.

An orthophoto is different than a common photo because it has been geometrically corrected for distortions caused by the terrain and  the orientation of the aircraft and camera lens.  Unlike a common photograph, an orthophoto has been rectified, meaning that it can be used to accurately measure distances and areas.

“This orthophoto is a snapshot that shows the Bow and Elbow rivers, at that particular time,” says Bruce Cullen, Director of Infrastructure & Information Services at The City.  “This orthophoto does not necessarily indicate the maximum high water line or how the water got there.”
To view and download sections of the June 22, 2013 orthophoto, visit  An instructional PDF file and video are available on the site to assist users in viewing and downloading your preferred sections of orthophoto.   

For optimal viewing and download, it is recommended that citizens use Internet Explorer to download the files.  It is also recommended that the files be downloaded to a USB flash drive (minimum 2 GB) that is able to hold large files. 

Citizens are asked to be patient during the download process, as the files are large in size (200 MB each) and may take a few moments to download.

1 comment:

  1. I tried to download some images following your directions. It didn't work. A few things (I'm using Google Chrome):

    1. If the map viewer window is enlarged too big a bug causes the satellite image overlay to disappear. On my system I maximized the window and at my monitor resolution of 2560x1440 it caused no overlays to appear. Only by shrinking the window into a smaller box did the overlays appear.

    2. Even with the overlays showing, I was unable to make any selections of sections, as the instructions tell me to do. The city isn't still custom coding just for Internet Explorer is it?

    3. I can manually add each image to my cart without using the map, but it's such a hassle. Can't you package them all together?

    4. Why don't you start a torrent for this? Instead of using this clumsy awful process to try and get an image just let people download them all in a torrent. It's much simpler and easier. It's 2014 after all.