What is GIS?
A GIS (Geographic Information System) is a computerized database
that combines precise spatial locations with attributes that describe those
features. Generally speaking, it is a combination of hardware, software, spatial
data and personnel used for mapping and analysis.
GIS allows us to view,
understand, question, interpret, and visualize spatial data in many ways that
reveal relationships, patterns, and trends in the form of maps, globes, reports,
and charts. Geologists and GIS Specialists at the WSGS use Geographic
Information Systems (GIS) to map and analyze Wyoming’s geology. GIS allows the
staff to combine the use of computers, digital data, and specialized software to
display, analyze, and store information related to the Earth’s surface. Data
sets may be thought of as compatible layers that can be overlain and queried to
explore spatial patterns and relationships.
Typical GIS data layers created at
the WSGS include bedrock geology, surficial geology, fault locations, and
mineral deposit locations. The data sets include locations of geologic features
and tabular data about the features. Tabular data may include ages,
descriptions, abbreviated nomenclature, and other characteristics.
Geologic GIS
data can be combined or overlain on data from other sources. Examples of
external data used by the WSGS include information on roads, streams, cities,
and elevation. GIS has all but replaced traditional manual cartography
techniques, allowing maps to be designed, edited, and stored on computers. The
map data is digital and portions of the map or the entire map can be viewed on
computer screens. Digital maps can be printed on large plotters when paper
copies are desired. In addition to cartographic work, the GIS office can scan
paper maps up to 42" wide and laminate maps up to 40" wide.
Scanning maps into a
digital format allows them to be used with GIS. In order for a scanned image to
be used in a GIS, it needs to be geo-referenced, or assigned spatial coordinates
in order to locate it at the proper location on a digital model of the earth.
The format of these datasets vary by use and the amount of work involved in the
transformation process. The simplest format uses the scanned map as a background
image, while more complicated formats include “heads-up digitizing” of the map
to create vector data. To learn more about GIS visit USGS GIS.