Introduction to GIS

Joy Suh Geospatial Resources Librarian

(hsuh1@gmu.edu)

2019

What will cover today? • Basic Concepts of GIS

• Applications of GIS

• Data Resources

• Software Access & Training

• Hands-On with ArcGIS-ArcMap

Geographical Information Systems (GIS)

A computer-based data management systems to help

create, visualize, store, manipulate and analyze

information that is tied to a geospatial data (location

data).

Geospatial Data

• “Information that identifies the location of

geographic features and characteristics of natural

or man-made objects on the earth”

So called “geographically reference data” or

longitude and latitude (XY), or spatial data

Ways to Collect Geodata • Address Data (in Spreadsheet format or place

name)

• XY Data (in Spreadsheet format)

• Print map (scanned Image of a map) (JPEG)Georeferenced image (via

georeferencing)

• Digitizing

• GIS Data available from authorized sources or on

Web

See: http://infoguides.gmu.edu/geospatial

Tabular Examples (.csv .xlsx .txt)

Geographical Unit is a observation unit

Two Types of Geospatial Data

Vector Data Raster Data • Represent “Real Word

View” based on:

Point, Line and Polygon

• Common Data format:

Shape file (.shp)

• Example: US Census

Tiger files

• Represent “Real World View” based on: Grid (Pixel)

• Data format: Digital Image

File

(. geoTiff, tiff, jpg, etc)

• Example: Remote Sensing

Satellite Imagery (NOAA or NGA)or Scanned images (USGS DOQQ)

“Feature Based Data”

Type of Geospatial Data • Point, Lines, Polygons, Grids—Typology data type

Vector Data (.shp) Raster Data (.geotiff)

Type of Data: Vector (Attribute Info)

• One row =each feature (Geography) on map

• .dbf

Vector: Common format Must have these three files:

• .Shp (geometry of feature)

• .dbf (attribute table)

• .shx (index of the geometry)

>If downloaded as a zip file, muse unzip it for ArcGIS

Desktop.

>Most usually comes with a six plus files

>Must keep them together as a folder to use.

Type of Data: Raster (Attribute Info)

• Grid of cells

Which is vector or raster data?

How does GIS work?

Capability: Overlay Layers

Capabilities: Data Overlay

Create a new layer through overlay (with the same location and the same

coordinate system)

Example: Overlay different data formats and create a new layer.

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Geographic Coordinates

• Latitude= North (+) or South (-) from 0 (Equator) to 90 at the N/S Poles

• Longitude = East (+) or West (-) from the Prime Meridian

3 Dimensions

Geographic Coordinates

X

Fairfax, VA Lat(Y)= 38.8505 Long(X)= -71.3032

Units= Degrees, Minutes, Second or Decimal Degrees.

• can convert between the two

2 Dimensions

Projections and Coordinate Systems

• Geographic Coordinate System (GCS) - Location on a sphere (latitude/longitude, 3 dimension)

• Datum (goes along with the GCS) - An estimate of Earth’s actual shape fit into a spheroid

(World Geodetic Survey (WGS) 83, NAD27(83)

• Projected Coordinate System - Location on a flat map from a defined 0,0 origin

See more at:

http://egsc.usgs.gov/isb/pubs/MapProjections/projections.html

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Projection Continued

Data Alignment in GIS

Define a Coordinate and Use the same coordinate for Data Alignment (source: http://pro.arcgis.com/en/pro-app/tool-reference/editing/align-features.htm)

No Spatial Information

Spatial Information Spatial Reference needs to be defined in GIS

Benefits (Principles) of GIS

• Visualize and interpret patterns and relationships

• Analyze spatial information and trend (Spatial

Analysis, Spatial Statistics, Network Analysis,

Space_Time Analysis, etc)

• Ask interactive spatial questions

• Predict future impact and create models

• Develop effective solutions

• Display and communicate spatial information

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Source: http://mason.gmu.edu/~aaburiza/snowCholeraMap/ For 2015 GIS Day Demonstration @Mason : GIS and Health

Applications of GIS

• Academics--interdisciplinary

• Federal (USGS), state, & Local Agencies

• Industry (www.esri.com> Industries)

See Library Databases and search”GIS”

• 2008 Presidential Election (Univ. of

Stanford)

• Mapping Inequality (Univ. of Richmond)

Brainstorm Your Map with Data

• Map Outcome: static vs interactive, share with

public, etc.

• Geography (Census Hierarchies, i.e) and Data Types

(Point, Polygon, Raster (image), i.e)

• Any similar project(s) to use as a reference

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How to Find Geospatial Data?

Library Infoguides—Geospatial Data & GIS

http://infoguides.gmu.edu/geospatial/data

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GIS Software & Training • Desktop—ArcGIS 10.6.1, QGIS (Open Source)

• Online: ArcGIS Online (AGOL), CartoDB,

• See more: infoguides.gmu.edu/geospatial/software

• Training: Data Services/GIS Workshops.

• ArcMap ArcGIS Pro (Install via the Desktop version

or individual download from Online)—Require

institutional accounts.

Hands-on Session

•ArcGIS 10.x— Be familiar with Tool Bars

(ArcMap, Arc Catalog, Arc Tool Box) •Do “ArcGIS Basic Exercise” (from the GIS Tutorial page)

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Contact & URLs

Joy Suh: hsuh1@gmu.edu

Rohan Bidarkoda :rbidarko@masonlive.gmu.edu

Infogudies.gmu.edu/geospatial

https://dsc.gmu.edu/gis/

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