Beginner’s GIS

Beginner’s GIS

Biodiversity Informatics Training Workshop

June 2012

Outline

• What is GIS• GIS & Map

Fundamentals• Spatial Data Types• Data Formats• Software• DEMO/Exercises

What is GIS?

GIS = Geographic Information System(s)

GIS is a collection of computer hardware, software, and geographic data for capturing, managing,

analyzing, and displaying all forms of geographically referenced information.

Environmental Systems Research Institute (ESRI), 2007

What is GIS?

An “image” with attribute information

What is GIS?

Tool to make complex patterns simple

What is GIS?

Environment for integrating diverse data

Overview of spatial data

Raster and vector data collide

Overview of spatial data

Points, lines, and polygons

Vector data

Vector data

• Shapefiles are common vector format of GIS data

Shapefiles consist of 3 main components:*.shp – main file stores geometry*.shx – index of geometry*.dbf – database of attributes

Shapefiles may also have:*.prj – plain text file of projection*.sbn and *.sbx – spatial index of features*.atx – index of attributes*.shp.xml – metadata

Vector data

Resolutione.g. 4 x 4 km

Raster Data

General data issue: spatial scale

Decrease in resolution

Increase in extent

Spatial scale has two elements: resolution and extent

Resolution

Ext

ent

In practice, resolution and extent tend to beinversely related

Resolution= cell size

Raster Data

15 KM pixel

7.5 km per pixel

4.5 km per pixel

1 km per pixel

Raster data - interpolation

Raster Data

Inverse distanceweighting

Kriging PolynomialsOr Spline

Raster data - interpolation

Raster Data

Inverse distanceweighting

Kriging PolynomialsOr Spline

Raster data - interpolation

Raster Data

• Using linear-weighted set of samples (greater the distance, the less influence on output raster value)

• Good for dense sampling

• Statistical method that fits a function to a radius of points, assuming a spatial correlation in distance or directionality

• Interpolated surface do not pass through sample sites

• Many different types

• Uses a mathematical function to create a minimize overall surface curvature

• Sample points pass through surface

• Best for variables like T

Raster data - interpolation

Raster Data

Environmental Data: conversion to raster

Weather station records (vector point data)

Interpolated raster climate surfaces (grid)

WorldClim Method: Hijmans et al. 2005

Gridded Climate Models are not just for climatologists any more…

Prism vs. Worldclim

Prism vs. Worldclim

Raster data - remote sensing

Raster Data

Raster data - remote sensing

Ned Horning, Center for Biodiversity and Conservation, AMNH

Raster Data

Raster data - remote sensing

Passive:

Natural EM radiation

e.g. Infrared,Aerial light

photography

Active:

Sensor EM radiation

e.g. RADAR,LIDAR

Raster Data

Common formats:•ESRI ASCII (.asc)•ESRI Grid•Geotiffs (.tif)•Any raster file can be used as a GIS grid

Also:•MrSID•netCDF•BIL

Raster Data

Raster Data

What’s in an ESRI grid?•dblbnd.adf•hdr.adf•sta.adf•vat.adf•w001001.adf –>

actual raster data

•w001001x.adf•prj.adf (opt)

Vector v. Raster

Tradeoffs between the 2 types of data

Tradeoffs between the 2 types of data

Vector v. Raster

Software

GIS software Win Mac GNU/ Linux Unix Web

CARIS Y N Y Y Y

Chameleon Y Y Y Y Y

ERDAS IMAGINE Y N N Y N

ESRI ArcGIS Y N Y Y Y

DIVA-GIS Y Winebottler N N N

GeoServer Y Y Y Y Java

GeoTools Java Java Java Java N

GRASS Y Y Y Y via pyWPS

IDRISI Y N N N N

ILWIS Y N N N N

JUMP GIS Java Java Java Java N

LandSerf Java Java Java Java N

Manifold System Y N N N Y

MapInfo Y N Y Y Y

MapServer Y Y Y Y Y

Maptitude Y N N N Y

Oracle Spatial Y Y Y Y Y

PostGIS Y Y Y Y Y

Quantum GIS Y Y Y Y Y

Smallworld Y ? Y Y Y

SPRING Y N Y Solaris N

TatukGIS Y N N N ?

TransCAD Y N N N Y

TerraView Y N Y N N

TNTmips Y Y Y Y N

TransModeler Y N N N N

ArcGIS• Commercial software, but ESRI Conservation Program grants

support non-profits with free licenses• ArcGIS is a suite of applications: ArcMap, ArcCatalog, ArcTools• Lots of extensions and interacts well with python and R stats with an

extension• Includes, web server, web services, online GIS, and freeware

(ArcExplorer)

DIVA-GIS• Free, not open source• Designed for niche modeling: Bioclim, Domain

uantum GIS• Open source,

• Functionality from plugins in C+ or python

• Access to GRASS and R routines

Some GIS Software Resources• DIVA-GIS

– http://www.diva-gis.org/

• Quantum GIS– http://qgis.org/

• Free Geography Tools – http://freegeographytools.com/

• GISLounge– http://gislounge.com/

• FreeGIS.org– http://freegis.org/

Some GIS Data Resources• Climate Data:

– http://www.worldclim.org/– http://www.prism.oregonstate.edu

• Global Land Cover Facility– http://www.landcover.org/

• EarthExplorer (US DEM, LC) – http://edcsns17.cr.usgs.gov/NewEarthExplorer/

• USGS Seamless Viewer– http://seamless.usgs.gov/

• Global Administrative Boundaries– http://www.gadm.org

Pearson and Dawson 2003 Global Ecology and Biogeography

Scale / Environmental Variable Dependencies