The images are compared with one another to determine significant changes in landcover. Each Landsat MSS image consists of four separate bands. Below is an RGB image of Houston, aquired in 1992. The red component of the image is band 1, the green component band 2, and the blue component band 3. This is the spatial extent that will be used throughout the course of the study.
Several landmarks are quickly identifiable.
One can easily pick out the downtown region, colored a light blue-gray, as well as many streets and highways emanating from it. Bush Intercontinental is located near the top of the image, with Lake Houston to the east. Fortunately, the images were all aquired at nearly the same time of the year, during late spring or early summer. During this season any vegetation in the image should be near its greenest levels. Also, the sun elevation angle is nearly constant for all three images, thus eliminating one possible source of error.