Geospatial Technology

Article excerpt

Geospatial technology refers to a system that is used to acquire, store, analyze, and output data in two or three dimensions. This data is referenced to the earth by some type of coordinate system, such as a map projection. Geospatial systems include thematic mapping, the Global Positioning System (GPS), remote sensing (RS), telemetry, and Geographic Information Systems (GIS) (USGS, 2000).

Each of the above subsystems are elaborate fields unto themselves; however, researchers are linking them together to better understand the world in which we live. Learning about these systems will help students to address an important component of technological literacy. Primarily, students will develop the abilities to assess the impact of products and systems (ITEA, 2000).

Thematic Mapping

The science of mapmaking, cartography, has been around for centuries, and no one is sure of its true beginnings. Cave drawings have been found that highlight hunting and other food sources, but other types of maps disappeared for various reasons. The main issue was the lack of a quality, long-lasting medium on which to draw maps. A second reason was the advance in mapmaking practice. As newer maps became more accurate, older maps were discarded.

The modern era of mapping began when explorers were able to navigate the globe on a regular basis during the 1500s. This allowed for a steady progression in methods and accuracy. In the 1800s, the first aerial photographs were taken from balloons, and the period of thematic mapping began.

Thematic mapping utilizes cartography, aerial photography, satellite imaging, and the plotting of data (e.g., vegetation, species, or static points) to interpret an area under investigation (USGS, 2000). Researchers are able to identify many objects by looking at physical characteristics such as color, density, or even how an object gives off or retains heat. Figure 1 shows a satellite image that could be utilized to research many variables.

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The data that are gathered in thematic mapping are stored in a quantitative fashion. This allows maps to be actively linked to databases, thus giving researchers a variety of ways to analyze the data. They can select a region from the map to pull up data or they can perform searches through the database. New maps and datasets can quickly be generated and analyzed. Analysis is often only limited by the creativity of the researcher.

Global Positioning System

The Global Positioning System (GPS) was developed by the United States Department of Defense for military applications in 1978, but in the 1980s it was opened for civilian use. GPS contains a space segment (satellites), a control segment (ground stations), and a user segment (anyone with a GPS receiver) (Garmin International, 2000).

The space segment consists of 24 satellites--21 active and 3 spares. The satellites are in six different orbital planes approximately 12,000 miles above the earth. This spread allows each satellite to cover a large area. A user must receive signals from four satellites for accurate locations in three dimensions (latitude, longitude, and altitude).

The GPS ground stations measure signals from the satellites and create orbital models for each satellite. The models compute precise orbital data (ephemeris) and clock corrections for each satellite. The Master Control Station at Schriever Air Force Base in Colorado uploads ephemeris and clock data to the satellites. The satellites then send subsets of the orbital ephemeris data to GPS receivers over radio signals.

The user segment of GPS has gained widespread notoriety from many outdoor sports. Golfers, fishermen, hunters, hikers, and other sports enthusiasts have widely embraced the accurate locations supplied by GPS. However, GPS also offers many significant advantages to the field of geospatial technology.

GPS is one of the primary geospatial tools for gathering and analyzing data. …

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