GIS Principles & Methods: Lecture Notes from MIT's Urban Studies and Planning - Prof. El M, Lecture notes of Information Technology

lecture note for the geographical information system course

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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
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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.”

„ What phenomena are we interested in studying? – Learning and discovering.

„ Think about the “Why.”

„ 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.

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.

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 ƒ many options ƒ review 'symbology' page of layer properties ƒ review ArcGIS help files for symbology o Different classification schemes (show help page): ƒ Equal Interval ƒ Natural Breaks ƒ Quantile ƒ Standard Deviation o Normalization: people or population density - Why do we care? (show examples)

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 ƒ pass window size and coordinate system information to web service on ortho server ƒ add returned image as registered raster layer in ArcMap o Later in semester, we'll use other web services that adhere to interoperable geospatial service protocols promoted by the Open Geospatial Consortium

Last modified 14 September 2005 [jf]