A
GIS organizes information associated with specific geographic
locations into a database that can be queried by topic and
location. The results can be displayed as maps with overlays
of various kinds of information, allowing the spatial relationship
of the data to be seen.
For example, highly detailed topographic data and fine-resolution
remote sensing photographs, each shown as an array of tiny
grid squares or pixels, necessarily contain huge amounts
of information. When combined by the GIS, these two kinds
of files can be scaled, aligned and merged to create a realistic
3-dimensional image, essentially a photograph draped over
a digital terrain model. Such a computerized visualization
can be colored, annotated with text, overlaid with information
generated from other databases, seen from various viewpoints,
and even animated so that it tilts and rotates. A GIS needs
fast computers able to handle the large amounts of data.
The data storage capacity of this system is 2.3 terabytes
of information. A terabyte (TB) is a million megabytes (MB).
