Aerial Photography and Orthoimagery

Aerial Photography

The currently holds 59,093 paper air photos, focusing primarily on London and Southern Ontario. Holdings include photos dating from 1922 to 2001 and are filed primarily by county. Urban areas are very often found within the county coverage (ex. the town of Strathroy is included in Middlesex County).  Specific urban places are also filed separately for quick reference, and are listed below. Air photos can be scanned at our GIS and scanning workstation at a resolution of your choice (up to 600dpi).  Patrons should be aware of what can and cannot be copied by reviewing the Canadian Copyright Act. Copies of the Act and the agreement with the University are posted in the Map and Data Centre.

We ask that once you are finished examining or scanning an air photo please DO NOT refile it.  It should be left either on top of the air photo filing cabinets or in the return basket near the workstation.

Filed with each set is a detailed flight line index to help locate specific aerial photographs. If you experience difficulty in finding your area of interest, it may be helpful to examine an National Topographic Series (NTS) 1:50,000 map or an Ontario Base Map (OBM) 1:10,000 map to pinpoint the exact location. This can be compared to the flight line index to determine whether or not your area of interest is included in our coverage. The following lists indicate the extent of our coverage.

County Coverage by Time Period

Urban Coverage

Digital Aerial Photograph Coverage

Special Collections

Digital Orthoimagery (DOI)

A Digital Orthoimage (DOI) is a remotely sensed aerial image, stored in raster format, such as MrSID, GeoTiff and JPEG.  DOIs are georeferenced and adjusted to remove any displacements associated with aerial photography.  The effect is that DOIs have a constant scale, use map projections and coordinates and can be used in GIS software, such as ArcGIS 10.x.  DOIs can be either colour or black and white.

All DOIs held at the are available to the University of Western Ontario faculty, students and staff.  Data must be requested in person at the Map and Data Centre reference desk and a release agreement must be signed.   The Map and Data Centre has 2 workstations equipped with ArcGIS 10.x and other software to view/manipulate the data.  UWO patrons may also copy the orthoimagery to a data storage device (ex. USB flash drive, CD-R) for research or teaching purposes.

Satellite Imagery

The Map and Data Centre also has a small collection of satellite imagery including IKONOS and Landsat 5 and 7 imagery.  All satellite imagery available at the Map and Data Centre has been processed as either MrSID, GeoTIFF or PIX raster file formats.

Before selecting an appropriate image it is important to note the difference between satellite imagery data and composite satellite images.  Satellite imagery data consists of separate raster files per band, which can be manipulated in digital image processing software, such as PCI Geomatica, ERDAS Imagine, ArcGIS or ENVI.  Satellite imagery data can be used to find the Normalized Difference Vegetation Index (NDVI), estimate crop yields, trace erosion, etc.

Composite satellite imagery can be described as a colour image produced through a combination of multiband images.  Although these images are visually appealing, they are only a combination of three spectral bands and are therefore very limited in digital image processing applications.