Post on 22-Dec-2015
Geographic Information Geographic Information SystemSystem
By: By:
Scott WiegalScott Wiegal
Mitchell Mathews Mitchell Mathews
What is GIS?What is GIS?
GIS represents real world objects that are GIS represents real world objects that are spatially referenced (have a location).spatially referenced (have a location).
There are two types of reference points; There are two types of reference points; either absolute (e.g., latitude/longitude) or either absolute (e.g., latitude/longitude) or
relative (what’s it next to?)relative (what’s it next to?)
Space can be conceptualized into two Space can be conceptualized into two abstractions: Discrete (raster) and abstractions: Discrete (raster) and
Continuous (vector).Continuous (vector).
RasterRaster
Made up of individual cells Made up of individual cells each with their own valueeach with their own value
e.g., Color is defined by 8 bits e.g., Color is defined by 8 bits for Red, Green, and Blue; for Red, Green, and Blue; 24 bits24 bits
Once created; can’t be scaled to a larger size or to a Once created; can’t be scaled to a larger size or to a lower resolution without loss of qualitylower resolution without loss of quality
Raster graphics are more practical than vector Raster graphics are more practical than vector graphics for photographs and photo-realistic graphics for photographs and photo-realistic imagesimages
VectorVector
Made up of points, lines, Made up of points, lines, and polygonsand polygons
One defined color for the One defined color for the line and one for the fill-inline and one for the fill-in
Plotting of points doesn’t lose quality when Plotting of points doesn’t lose quality when resolution is changedresolution is changed
Vector graphics are more practical for Vector graphics are more practical for boundariesboundaries
Raster Vs VectorRaster Vs Vector
Raster Discrete
Vector Continuous
Raster Vs VectorRaster Vs Vector
Vector AdvantagesVector Advantages1. Minimal amount of 1. Minimal amount of
informationinformation
allows for smaller file size.allows for smaller file size.
2. Indefinite zoom will keep 2. Indefinite zoom will keep
lines clear and proportionallines clear and proportional
3. Use of arbitrarily precise 3. Use of arbitrarily precise (X,Y)(X,Y)
coordinates allows for morecoordinates allows for more
accurate measurementsaccurate measurements
Raster AdvantagesRaster Advantages1. Easier and more descriptive 1. Easier and more descriptive
use use
of combining layersof combining layers
2. Displays varying surface 2. Displays varying surface featuresfeatures
more effectivelymore effectively
3. Ideal for satellite imagery3. Ideal for satellite imagery
because of its detailed because of its detailed naturenature
Applications – ArcGIS (ESRI)Applications – ArcGIS (ESRI)
Vector program for GIS & Mapping Vector program for GIS & Mapping SoftwareSoftware
77% of GIS professionals use some 77% of GIS professionals use some formform
Desktop, Server, and Desktop, Server, and
Mobile offeringsMobile offerings
Applications – ArcIMS (ESRI)Applications – ArcIMS (ESRI)
Is an Internet Mapping SolutionIs an Internet Mapping Solution Ideal for sharing information online Ideal for sharing information online
due to its multi-tier systemdue to its multi-tier system
Applications – IDRISI (Clark Applications – IDRISI (Clark Univ.)Univ.)
Raster geographic software packageRaster geographic software package Inexpensive but professionalInexpensive but professionalMost widely used raster system in Most widely used raster system in
worldworld
Applications – GRASS (Open Applications – GRASS (Open Src)Src)
GRASS – Geographic Resources GRASS – Geographic Resources Analysis Support SystemAnalysis Support System
Package of 350 programs that deals Package of 350 programs that deals in both vector and rasterin both vector and raster
Uses - MapquestUses - Mapquest
Corvallis – City Level
Corvallis – Street Level
Uses – FirefightingUses – Firefighting
Vector
Raster
Uses – Wildlife MgmtUses – Wildlife Mgmt
Raster
Vector
Uses – Real EstateUses – Real Estate
Uses - InsuranceUses - Insurance
FinFin