So What is GIS??? “A collection of computer hardware, software and procedures that are used to organize, manage, analyze and display geographically referenced datasets.…"

Organizing Spatial Data A GIS works with thematic layers of spatial data Answer questions by comparing different layers of data

Five Components GIS An integration of five basic components A Procedures

Query Analyze StoreDisplay Capture Output GIS Functions

Capturing Data , , , , , Coordinates Paper maps Digital data GPS GIS Data

Components of Geographic Data Three general components to geographic information Attributes Geometry Streets Behavior Rules Streets and highways may not intersect

Basic Elements of Spatial Data Space –Location in space requires a georeferncing system Time –Location in time Accuracy Data Models and Formats Attributes –System for defining attributes

So How Do We Build A GIS?

X,Y Reality (A highway) X,Y Rows Columns Data Models Vector formats –Discrete representations of reality Raster formats –Use square cells to model reality

Vector Data Points, Lines and Polygons Good for representing discrete objects: buildings roads, etc. Smaller data storage needs

Raster Models Good for modeling continuous data Creation of surfaces Modeling interactions between layers Large data storage needs

Images & Grids Rows and columns of equal-sized cells –Each cell stores a value –Detail depends on cell size Grids (the ESRI native raster format) Images (TIFF, BMP, SID, JPEG, ERDAS)

Spatial Data Formats ArcGIS works with multiple spatial data formats ArcGIS CAD Coverage Geodatabase Shapefile Raster Tables Internet Map Service

Which parcels are within 50 feet of the road? Well type Drilled Building owner Smith Soil type Sandy GIS Analysis Functions Proximity Overlay Network

Maps Graphs Display Reports

DocumentImage Types of Output Internet Paper map GIS Data