A technological field addresses geographical features with tabular data in order to map, analyze, and assess real-world problems and its instant solutions. The key word to this technology is Geography means that the data locations on the earth.
ESRI Quotes GIS Design as:
A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on earth. GIS technology integrates common da-tabase operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps.” ESRi
The method of digitizing directly on top of an orthorectified 0.4 Meter Satellite imagery. The for-mation of each parcel, roads, civil and other infrastructures, underground utilities gives us clear pic-tures of require information. Further, the level of accuracy of the derived dataset is taken from the digital satellite imagery.
This method is highly precise as entering the actual survey measurements of the property lines cre-ates the database. Distances and bearings are entered into the GIS from the original surveyor plats. The GIS software builds the digital vector file from these values.
Geocoding is another keyboard-based method. Geocoding uses addresses from a flat file (such as a .dbf file, MS Access database or excel spreadsheet) to create x,y coordinate locations interpolated from a geocodable spatial database. These spatial databases are most commonly street centerline files but can be other types. The resultant geocoded database is a point file. For more information read my article called “Geocoding 101.”
Global Positioning Systems (GPS)
GPS is a way to gather accurate linear and point location data. Originally devised in the 1970s by the Department of Defense for military purposes, the current GPS consists of 28 satellites that orbit the earth, transmitting navigational signals. Through interpolation, these signals received by a data logger can pinpoint the holder’s location. Depending on the unit, the locational accuracy can reach to the millimeter. Combined with attribute data entered at the time of collection, GPS is a rapid and acccu-rate method of data collection. For more information access Trimble’s excellent tutorial on GPS.