Satellite images come in a different format and serve different purposes. These images can be used to visualize features on Earth using real colors or they may be used to identify a variety of characteristics using parts of the spectrum invisible to the human eye.

As we saw, our sample image had three channels (blue, green, and red) that were combined in a single file to compose a real color image. Different from the sample image, most satellite data comes with each channel separated into a file for each one of them. These channels are called bands and comprise of a range of the electromagnetic spectrum visible or not to the human eye.

In the following examples, we are going to use the digital elevation models (DEM) generated with the data obtained by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER).

These DEM have a resolution of approximately 90 m and the values are stored in the 16 bits signed integers representing the...