# Data Day 2012_Fradkin_Intro to GIS

## by Metropolitan Area Planning Council

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## Data Day 2012_Fradkin_Intro to GISPresentation Transcript

• Introduction to Data Mapping Barry Fradkin GIS Analyst Metropolitan Area Planning Council Friday, January 27, 2012
• Data Mapping
• More geographic data becoming available
• See patterns that aren’t otherwise apparent
• What are the properties of spatial data?
• Where can we find spatial data?
• How do we make maps ourselves?
• Geographic Information Systems
•
• Social Networking
• Population Bostonography.com
• Transportation Bostonography.com
• Coordinate Systems
• Cartesian Coordinate System
• Geographic Coordinate System
• Latitude and Longitude
• Boston
• 42°21′28″N, 71°03′42″W
• 42.359228, -71.061515
• Understanding Projections
• Earth is roughly spherical
• Maps are 2-dimensional
• Distortion is inevitable
• Types of Projections
• Mercator is common
• Specialized projections for smaller areas
• For Massachusetts: NAD 1983 State Plane Massachusetts (m or ft.)
• Data Models
• Feature geometry can be shown in two ways:
• Vector
• Points, lines, polygons
• Discrete objects
• Raster
• Grid of cells
• Continuous data
• Attributes
• The information behind the geometry
• Similar to Excel or Access tables
• Types of attributes:
• Nominal (text)
• Ordinal (rank)
• Interval (numeric)
ID Nominal Ordinal Numeric 1 residential low 10 2 industrial high 700 3 commercial medium 14.625 4 open space very low 0.263
• Attribute Formatting
• Headers: no spaces or special characters
• UPPER CASE / lower case / Sentence Case
• Number format makes a difference
Number Format Minimum Value Maximum Value Short integer -32,768 32,767 Long integer − 2,147,483,648 2,147,483,648 Float Many digits, decimals Many digits, decimals Double More digits, decimals More digits, decimals
• Where to find the data?
• MassGIS – Office of Geographic Information
• Municipalities, roads, water, land use
• US Census: blocks, block groups, tracts
• Air photos, elevation, impervious surface
• Data tables from state and federal gov’t.
• Unique IDs can be used to join to geography
• Geocoding
• Latitude/Longitude (decimal degrees)
• Digitizing
• Manually draw features from air photo
• Georeference an existing map image
• Join your own tables to existing geography
• Displaying the Data
• Data layers
• Symbology
• Colors
• Point size
• Line width
• Labels
• Font size
• Positioning
• Cartography
• All maps should have:
• North Arrow
• Scale Bar
• Legend
• Title
• Date
• Source
• Make text large enough to be legible
• 5 to 10% of men are colorblind
• Colorbrewer.org:
• GIS Software
• Online mapping tools:
• MassGIS OLIVER: http://www.mass.gov/mgis/mapping.htm
• MetroBoston DataCommon: http://metrobostondatacommon.org/