Intro%20to%20Geospatial%20Data

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Intro to Geospatial Data

• Jon Jablonski
• February 26, 2002
• For ASIS(t) UW

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Agenda
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Whats it about?

• Entities
• Attributes

• Urban
• City Hall
• 4 per acre
• 615 smoots

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Maps ? GIS

• But in a way they are.
• Same primitives
• Also consist of layers
• Answer some of the same questions.

• GIS
• is dynamic
• is a data structure
• can be queried
• can create new information

both are cool.
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Whats unique about spatial info?

• Ties an attribute to a location, without losing
  the ability to be structured, to be operated
  upon, to be transformed, and to be moved.
• Is a representation of 3d space onto 2
  dimensions.
• But people are working on leaping into 3d.

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What are some attributes?

• Measurements are most common, and relate directly
  to research methods (570 anyone?)

Graphic Geog 360, Nick Chrisman
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Nominal
3941 Univ. Way10-H4545 Bldg3-I Academic Computer
Center13-G Aerodynamics Lab12-OAerospace
Research Bldg12-N Allen Library10-M Alumni
House3-IAnderson Hall14-M Architecture
Hall11-K Archives and Records11-G Art
Bldg6-N Atmospheric Sciences-Geophysics
12-LBagley Hall12-L Balmer Hall5-M Benson
Hall13-L
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Ordinal
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ARCview

• Views and themes.
• Basic interface to data
• Tables
• See the underlying structure.
• Layouts
• Make pretty pictures.

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Demowhat are you doing?

• Showing a layer with no context
• Adding a layer of stock data
• Adding some other unit to measure against
• Querying to restrict data set

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Answer me a question.

• Show me the Indian population in central
  Washington, indicating whether or not people are
  living on a reservation.

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Yakama Nation population.
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Steps

• Display Washington counties.
• Select only central Washington
• Invert selection
• Delete
• Add reservation areas from earlier map
• Select by theme to isolate areas of interest
• Do the same for Census blocks.

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Oh.

• I dont have the census blocks.

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Finding data on the web

• Library
• GISdepot
• ESRI
• Census
• Etc etc etc etc

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Places to find info

• https//wagda.lib.washington.edu/gis/uwonly/data/g
  eolytics/wash/
• http//www.census.gov/population/www/socdemo/race.
  html

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Select by intersection

• For finding part of one theme that intersect with
  another
• Can use as an attribute operation as well

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Heres a new problem

• Shapes arent quite the same.
• Data quality is a function of
• Whos collecting it.
• The scale upon which it is drawn.

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How the heck to combine then?

• Query whats in one to the other?
• Do it visually?
• How about 2 steps?
• Join into tract table
• Query for non-blank.

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Other operations

• Buffers
• Dont kill my fish
• Distance networks
• How far to the nearest bus stop.
• Scoring
• Many planning decisions made by completely made
  up formula
• A true cynic would claim that formulas are made
  up to get the desired answer.

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More Manipulation

• Calculate
• To build new fields when data doesnt match
• To create new information
• To solve your silly equations

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Buffers
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Network operations
And http//www.esri.com/library/userconf/proc95/t
o150/p113.html
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Scoring
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General ARChints

• File management is an issue.
• Temp files get huge
• Every layer has multiple files
• Deleting a layer doesnt delete its files
• Operations make new files that may not be
  destroyed automatically.