Data Day 2012_Fradkin_Intro to GIS

Introduction to Data Mapping Barry Fradkin GIS Analyst Metropolitan Area Planning Council Friday, January 27, 2012

About me…

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

Downloading from MassGIS

Compile your own data
Geocoding
Street addresses > Address Locator
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

Consider your audience
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/
Google Maps, Google Earth, OpenStreetMap
Open Source Software
Quantum GIS, GRASS, SAGA

ESRI ArcGIS
ArcMap
ArcCatalog
ArcToolbox
ArcScene
ArcGlobe
Cheap non-profit license available
esri.com/nonprofit

Data Day 2012_Fradkin_Intro to GIS

by Metropolitan Area Planning Council

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Data Day 2012_Fradkin_Intro to GIS Presentation Transcript