Geographic Information System By: Scott Wiegal Mitchell Mathews

What is GIS? GIS represents real world objects that are spatially referenced (have a location). GIS represents real world objects that are spatially referenced (have a location). There are two types of reference points; either absolute (e.g., latitude/longitude) or relative (what’s it next to?) There are two types of reference points; either absolute (e.g., latitude/longitude) or relative (what’s it next to?) Space can be conceptualized into two abstractions: Discrete (raster) and Continuous (vector). Space can be conceptualized into two abstractions: Discrete (raster) and Continuous (vector).

Raster Made up of individual cells each with their own value e.g., Color is defined by 8 bits for Red, Green, and Blue; 24 bits Once created; can’t be scaled to a larger size or to a lower resolution without loss of quality Raster graphics are more practical than vector graphics for photographs and photo-realistic images

Vector Made up of points, lines, and polygons One defined color for the line and one for the fill-in Plotting of points doesn’t lose quality when resolution is changed Vector graphics are more practical for boundaries

Raster Vs Vector Raster Discrete Vector Continuous

Raster Vs Vector Vector Advantages 1. Minimal amount of information allows for smaller file size. allows for smaller file size. 2. Indefinite zoom will keep lines clear and proportional lines clear and proportional 3. Use of arbitrarily precise (X,Y) coordinates allows for more accurate measurements Raster Advantages 1. Easier and more descriptive use of combining layers of combining layers 2. Displays varying surface features more effectively more effectively 3. Ideal for satellite imagery because of its detailed nature because of its detailed nature

Applications – ArcGIS (ESRI) Vector program for GIS & Mapping Software Vector program for GIS & Mapping Software 77% of GIS professionals use some form 77% of GIS professionals use some form Desktop, Server, and Desktop, Server, and Mobile offerings Mobile offerings

Applications – ArcIMS (ESRI) Is an Internet Mapping Solution Is an Internet Mapping Solution Ideal for sharing information online due to its multi-tier system Ideal for sharing information online due to its multi-tier system

Applications – IDRISI (Clark Univ.) Raster geographic software package Raster geographic software package Inexpensive but professional Inexpensive but professional Most widely used raster system in world Most widely used raster system in world

Applications – GRASS (Open Src) GRASS – Geographic Resources Analysis Support System GRASS – Geographic Resources Analysis Support System Package of 350 programs that deals in both vector and raster Package of 350 programs that deals in both vector and raster

Uses - Mapquest Corvallis – City Level Corvallis – Street Level

Uses – Firefighting Vector Raster

Uses – Wildlife Mgmt Raster Vector

Uses – Real Estate

Uses - Insurance

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