beginner’s gis
DESCRIPTION
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 = G eographic I nformation S ystem(s) - PowerPoint PPT PresentationTRANSCRIPT
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