What is GIS

GIS hardware includes: computers, computer configuration/networks, input devices, printers, and storage systems.

Computers for GIS usage can be PCs at the low end, or supercomputers and X-Terminals at the high end. These computers can be stand-alone units or can be hooked into a network environment. To assist with source data capture & real -time GIS data, many companies are employing handheld technologies in the form of PDA’s and GPS units. The latter also affords companies the ability to track moving features, adding a new dimension to their GIS solutions.

Input devices include digitizers and scanners. A digitizer is the device used for selecting features from a hard copy map, which are then registered to a coordinate system. Currently digitizing is the most common method for converting existing maps and images into digital form. However, this process can be tedious, especially when converting high-density maps. Scanners sometimes can replace digitizing by automatically converting hard-copy maps to a digital raster file. Once in a GIS, the raster image can be converted to a vector format through a “raster-to-vector” conversion.

The third hardware component is the printer/plotter. These devices are used to produce a hardcopy map. There are several types of printers including: matrix, inkjet/bubblejet and laser. Plotter types include: laser, electrostatic, direct thermal and pen plotter.

Finally, GIS storage systems include: optical disks, magnetic disks (such as a hard drive), floppy disks or magnetic tapes.

Obtaining data to insert into a GIS is a large subject in itself that includes a number of different approaches. One of the most common ways to collect spatial geographic data is to perform a physical survey to obtain primary/proprietary data. This includes surveying the land, underwater areas, and underground features of the earth (which are referred to as field survey, hydrographic survey and mining survey respectively).

Aerial photography/remote sensing is an increasingly popular way to gather spatial data. Aerial photographs are taken from an aircraft, after which they are measured and interpreted. Similarly, satellite remote sensing can be interpreted for physical features and attributes.

Censuses conducted by the U.S. Census Bureau gathers a variety of demographic data such as population, age structure, sex ratio, race composition, employment rates.

Statistics are a set of mathematical methods used to collect and analyze data. These methods include the collection and study of data at different time intervals and at a fixed location, providing information for yearbooks, weather station reports, etc. This information often has a spatial component and can thus be incorporated into a GIS.

Finally, tracking is a process of collecting attribute data on changes that occur at a location over a period of time. Examples of tracking include: monitoring the change of an ecosystem, and real-time monitoring of a moving objects such as vehicles using GPS technologies.

Public & Commercial Sources of GIS Data