GEOGRAPHIC INFORMATION SYSTEM. GIS are tools that allow for the processing of spatial data into information, generally information tied explicitly to, and used to make decision about, some portion of the earth. There is no absolutely agreed upon definition of a GIS.
Data Collection: aerial photos, surveys, etc.
Data processing: aggregation, classing, etc.; linear process
Map production: final step except for reproduction and dissemination
Data collection:aerial photos, surveys,etc.
Data processing: aggregation, classing, plus analysis; circular process
Map production: not always final step;normally one map used to produce still more
Map reproductionCOMPARISON OF CARTOGRAPHIC PROCESS AS APPLIED TO TRADITIONAL CARTOGRAPHY AND GIS
Input: recorded (compiled) on paper from a collected source
Input:”encoded” into the computer from a collected source
AreasANALOG VERSUS DIGITAL GISA COMPARISON OF INPUT SUBSYSTEM FUNCTIONS
Digital remote sensing
Statistical data, etc.
Same as map data
Digital line graph (DLG)
Digital elevation models (DEM)
Other digital databasesANALOG VERSUS DIGITAL GISA COMPARISON OF INPUT SUBSYSTEM FUNCTIONS
Points, lines, and areas are drawn on paper with symbols
Retrieval is simply a matter of map reading
Points, lines and areas are stored as grid cells or coordinate pairs and pointers in computer
Attribute tables are associated with coordinate pairs
retrieval requires efficient computer search techniquesANALOG VERSUS DIGITAL GISA COMPARISON OF STORAGE AND RETRIEVAL SUBSYSTEM FUNCTIONS
Requires rulers, planimeters, compass, and other tools all used by the human analyst
Restricted to the data as they are aggregated and represented on the paper map
Uses the power of the computer to measure, compare, and describe contents of the database
Allows ready access to the raw data and allows aggregation and reclassification for further analysisANALOG VERSUS DIGITAL GISA COMPARISON OF ANALYSIS SUBSYSTEM FUNCTIONS
Graphic device only
many forms of maps
Modifications can include cartograms, etc.
The map is only one type of GIS output
With minor exception, GIS offers same options as traditional hand-drawn maps
Also includes tables, charts, diagrams, photographs, etc.ANALOG VERSUS DIGITAL GISA COMPARISON OF REPORTING AND OUTPUT FUNCTIONS