The United States Geological Survey (USGS) operates the satellites Landsat 5 and 7 which provide images of medium resolution (15 m to 30 m) to obtain a regional profile and track the changes in the land at low cost .
Since January 2009, almost all the images captured by the Landsat 5 and 7 are available for free. The costs associated with projects using these images are kept to a strict minimum of image processing, ortho-rectification, enhancement, and mosaic. The Landsat 5 satellite captures images with a resolution of 30 meters over 25 years. Landsat 7 captures images with a panchromatic band with a resolution of 15 meters, but since 2003 it has a major breakdown producing partial images. However, GSF has developed a method to integrate these images to produce improved results.
You can browse the catalog of images available online through the browser http://glovis.usgs.gov/
GSF has produced several mosaics of Quebec, the Maritimes and Newfoundland for the years 1970, 1995, 2000, 2005, 2006, 2007, 2008 and 2009. Consult the page Landsat for mor information. |