Massachusetts Institute of Technology Department of Urban Studies and Planning 11 520 A Workshop on Geographic Information Systems 11 188 Urban Planning and Social Science Laboratory GIS Principles Methods September 14 2005 Joseph Ferreira Jr including contributions from Visiting Prof Zhong Ren Peng who taught the Fall 2003 class Administrative notes regarding lab exercises and schedule Lab Exercises 2 we ve made some minor edits regarding how to control the labeling it s different in new version ArcGIS 9 1 Lab Exercise grading o we aren t going to grade every detail o you ll get a check okay check plus especially good or check minus not as complete as we had hoped o all together the lab exercises count for 25 of semester grade Lab Exercise purpose o quick start with basic ArcGIS tools and features o highlight important ideas and methods o assist you in becoming more self sufficient with ArcGIS help pages o as semester progresses they will be less cookbook and a little more open ended o Don t just push the buttons to get the right answer pause to think about what you are trying to do what info tools are needed and why ArcGIS is organized in a particular way General Approach to the Course Understand the What Think about the Why What phenomena are we interested in studying Learning and discovering Why are spatial analysis and GIS tools relevant Critical thinking Master the How How do we solve the problem decompose a question into spatial analysis and visualization components that can be handled by the data and software How to distinguish different geographic information How do we represent geographic location How do we represent objects in space Are all maps equal Scale or level of geographic detail Must geographic information be mappable Shortest path algorithm Data Information and Knowledge where does GIS fit in Data Raw geographic facts context free Information the interpretation of data Knowledge interpreted information based on a particular content experience and purpose Why Spatial information is special 80 of all information includes spatial component Data Information and Knowledge relevant at every level Urban planning is inherently spatial Spatial relationships are as relevant as spatial location It takes spatial analysis to understand their relationship Spatial data are usually voluminous Presentation as a map often takes a huge amount of data Visualization and data consistency require use of particular map projections and spatial reference system Distinguish among images of a place streetscape aerial photo of a place orthophoto and a cartographic map of the same place Mapquest Distinguish among Mapquest NOAA hurricane map NOAA data buoy center EPA s Enviromapper MIT OrthoTools traffic reports and ArcGIS Where is knowledge of geographic location spatial analysis manipulation visualization capability What is GIS GIS is a computer based information system that enables capture modeling manipulation retrieval analysis and presentation of geographically referenced data Worboys 1997 Other definitions of GIS A container of maps in digital form A computerized tool for solving geographic problems A spatial decision support system A tool for revealing what is otherwise invisible in geographic information A tool for automatically performing operations on geographic data Components of GIS Hardware Software Data People humanware Procedure Network Internet Evolution of GIS A Timeline from 1970s to now The following contents of today s lecture is derived from Longley Goodchild Maguire and Rhind Geographic Information Systems and Science 2001 as organized by Prof Zhong Ren Peng for 11 520 in Fall 2003 GISytems GIScience GIStudies and GIServices GISystems A computerized tool that helps solve geographic problems GIScience A scientific approach to the fundamental issues arising from geographic information GIStudies the systematic study of society s use of geographic information including institutional organizational and procedural issues GIServices The business of providing GIS data and analysis tools to GIS users These concepts are derived from Longley e al 2001 Some Examples of GIS Applications Resources inventory what is available at where Network Analysis How to get to a place in the shortest amount of time Location Analysis Where is the best place to locate a shopping mall Terrain Analysis What is the danger zone for a natural disaster Visibility analysis Spatio Temporal Analysis What has changed at what locations over the last twenty years and why Overview of ArcGIS software What are the various parts of ArcGIS and what do they do How is ArcMap organized Understanding the vector and raster data models underlying ArcGIS Vector data models for geospatial location Geometry model o boundary representation vector model o points sales lines streets and polygons block groups o assign spatial feature ID to each spatial object Attribute data model o relational tables linked to spatial features via ID o graphical interface to utilize geometry attribute links Complications o islands lakes overpasses o share edges move links when you move points o ambiguity summer winter wetland boundaries o scale generalization conflation slivers o Coordinate systems and projections Thematic mapping tip of iceberg regarding GIS applications o Symbology many options review symbology page of layer properties review ArcGIS help files for symbology o Different classification schemes show help page Equal Interval Natural Breaks Quantile Standard Deviation Normalization people or population density Why do we care show examples o Raster vs vector data models regular grid on top of spatial features instead of encoding boundary pixel brightness in orthophoto of Boston Vector points lines polygons o Coverages old Arc Info a directory per layer plus INFO files o Shapefiles shp shx dbf files and possibly others o Spatial Database Engine SDE retrieved dynamically from a database server Raster orthophotos scanned maps grids o orthophoto has been unwarped and registered to a coordinate system o ortho can be treated as raster coverage layer where darkness of pixel is proportional to attribute of interest o ArcGIS has spatial analyst extensions to create and manipulate raster data layers and combine them via map algebra Boston Cambridge Streets superimposed on orthophoto Zoomed in view shows raster nature of the ortho MITOrthoTools o Installing the button o What it does pass window size and coordinate system information to web