GEOGRAPHIC INFORMATION SYSTEMS
Lecture 23: Spatial Analyst
Final Project Report
As part of the final project for this class, you will put together and submit a final project report on the Buffalo
Commons. I have provided an outline for the report that follows a standard format (see link on course web page).
Introduction
- describe the problem
- Great Plains experiencing and ongoing decline in rural population
- Poppers proposed the idea of a Buffalo Commons to diversify economy
- never stated explicitly where the Buffalo Commons would be established
- therefore, the purpose of this study is to find the best location for a Buffalo Commons
- $20 billion will be spent over 40 years – paying twice what the land is worth
Study Area
- describe the resolution of the analysis (county-level analysis)
- describe the spatial extent of the project (Great Plains states)
- include your study area map
Methods/Procedures
- to find the best location for a Buffalo Commons, a weighted site-suitability model was developed
- model includes five variables – list them
- then explain how each variable relates to the project
- population density – seeking to identify counties with a low population density
- population change – seeking to identify counties with large decline in population
- land value – seeking to identify counties with low land values
- federal lands – seeking to identify counties with a high percent of federal land
- adjacency to Indian lands – seeking to identify counties adjacent to Indian reservations
- first four variables ranked on a scale of 1-5, adjacency to Indian land ranked 0 or 1
- for each county, variables were added – maximum 21 divided by 4.2 – final ranking scaled 0-5
Analysis
- organize the analysis section with one section for each variable
e.g. Population Density
- describe the variable
- county population density based on what Census?
- describe the ranking
- counties with a low population density were assigned a value of 5
- counties with a high population density were assigned a value of 1
- what types of classification was used
- describe the type of classification used (quantile, natural breaks, etc)
- include a table to describe the class breaks (eg…below)
POP/SQ MILE
RANK
DESCRIPTION
0.1 - 2.9
5
Very Low
2.9 - 6.7
4
Low
- describe the map (where is the population density low and high)
Results
- the results of the site suitability analysis are shown on the Suitability map
- the most suitable location are those counties with the highest ranking
- describe the map (where are the counties with a high ranking)
- based on this final county ranking, I selected an area that encompasses…
- describe the map (where on the Great Plains do you propose a Buffalo Commons)
- this area(s) was selected because….
Conclusions
- restate the purpose of the study
- summarize and describe the results
- extend the results to describe other attributes
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ArcGIS Extensions
- recognize that are dozens of extensions to ArcGIS
- most of these extensions add tools to ArcToolbox and a toolbar to the ArcMap interface
- all of these extensions are designed to add more functionality (tools) to the core software
- some extensions are developed by Esri - some are developed by other software developers
- some extensions are available as a free download - some extensions require a software license
- examples include: Spatial Analyst, 3D Analyst, Geostatistical Analyst, Network Analyst, Tracking Analyst
Survey Analyst, Business Analyst, and Military Analyst
Using ArcGIS Extensions
- to use licensed extensions, you must first enable the extension license
- to do so, you select Extensions from the Customize pull-down menu on the ArcMap menu
- this will open the Extensions dialog box showing all of the licensed extensions that you have available
- check the box next to the extension to enable the license and make the extension available for use
- once a licensed extension has been enabled, the next step is to turn on the extension toolbar
- to turn on an extension toolbar, select Toolbars from the Customize pull-down on the ArcMap menu
- this will load the extension toolbar which can then be docked on the ArcMap interface window
Spatial Analyst
- Spatial Analyst is an ArcGIS extension designed to work with raster data - especially digital elevation models
- the major functions are accessed through ArcToolbox > Spatial Analyst
- in lecture I went through a series of demonstrations illustrating the use of several important Spatial Analyst tools
Distance - used to create a continuous raster distance surface from point, line or polygon features
- you can also create an direction surface and allocation surface
(a similar tool for vector data creates Thiessen polygons )
- to create a distance surface, ArcGIS calculates the distance to the nearest point, line or polygon
- in this example, the grid cells values are the distance to the nearest point (selected west Texas cities)
- to create a direction surface, ArcGIS calculates the direction to the nearest point, line or polygon
- in this example, the grid cell values are the direction to the nearest point (selected west Texas cities)
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- to create an allocation surface, ArcGIS allocates cells to the nearest point (creates Thiessen polygons)
- in this example, the grid cells values are feature class codes corresponding to the nearest point
Density - used to create a continuous raster density surface from point or line features
- for a density surface, ArcGIS calculates the density of points or lines per unit area
- in this example, the grid cell values represent the density of playa wetlands per square kilometer
- to calculate the density of playa polygons, we must first create the playa polygon centroids (points)
- then we calculate the playa density surface from the playa centroids
>
playa wetland polygons
>
playa polygon centroids (points)
playa density surface
(number of playas per sq kilometer)
Interpolate to Raster - used to interpolate a continuous raster surface from sample point values
- Spline - applies a smooth spline function to calculate the value of interpolated cells
- to interpolate a surface, ArcGIS estimates values for all of the grid cells between points
- in this example, we used well measurements to estimate the water table surfaces in 2000 and 2008
Well Measurements 2000 Interpolated Water Table Surface 2000
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Well Measurements 2008 Interpolated Water Table Surface 2008
Map Algebra – used to apply arithmetic or algebraic functions to raster surfaces
- the difference in water table elevation from 2000 to 2008 is calculated by subtracting one raster from
another. The difference raster clearly shows areas in red where the water table is declining and areas in
blue where the water table is not declining.
Difference 2000 to 2008
Surface Analysis - particularly useful set of tools used to analyze digital elevation models
- Contour (used to create contour lines from a DEM)
digital elevation model (DEM)
contours derived from DEM
- Slope (used to create a slope map from a DEM)
digital elevation model (DEM)
slope raster derived from DEM
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- Aspect used to create an aspect map from a DEM
- the cell values in an aspect raster give the compass direction the slope is facing eg.blue cells face north
digital elevation model (DEM)
aspect raster derived from DEM
- Hillshade used to create a shaded relief layer from a DEM. Can classify the DEM and overlay on a
hillshade
digital elevation model (DEM)
Shaded relief (hillshade)
classified DEM overlaid on a hillshade
- Viewshed (used to create a visibility surface relative to one or more observer points
- user specifies the location and height of observation points
- output raster shows cell that are not visible from the observation points (pink) and cells that are
visible to one or more observation points (light green).
digital elevation model (DEM)
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viewshed derived from DEM
GIST 3300 / 5300
Geographic Information Systems
Spatial Analyst
ArcGIS Extensions
Spatial Analyst Extension
- adding the extension
- loading the toobar
- major functions
- distance
- density
- interpolation
- map algebra
- surface analysis
Geographic Information Systems
Announcements
• LECTURE SCHEDULE
Nov 16
Nov 18
Nov 23
Nov 30
Dec 2
(Mon)
(Wed)
(Mon)
(Mon)
(Wed)
Final Project Report Instructions
Spatial Analyst
3D Analyst
Enterprise Applications
Sharing Data and Maps
• FINAL PROJECT DUE December 2 @ 12:00 NOON
TURN IN BEGINNING OF LECTURE
Or Slide under my door before Dec 2 in Room 118 Exp. Sci. Bldg
Or turn in to your TA before Dec 2
• FINAL EXAM – Strongly recommend begin studying now
Dec 7 Final Exam 10:30 am
• FALL 2016
GIST 4304 / GIST 5304 Advanced GIS
Geographic Information Systems
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ArcGIS Extensions
That Add More Functionality
- there are dozens of extensions to ArcGIS
- most of these extensions add a toolbar to the ArcMap interface
and tools to ArcToolbox
- designed to add more functionality (tools) to the core software
- some of the extensions are developed by Esri
- some have been created by other software developers
- some extensions are available as a free download
- some extensions require a software license
Geographic Information Systems
ArcGIS Extensions
That Add More Functionality
- Spatial Analyst – used mainly to analyze raster data
- 3D Analyst
- Geostatistical Analyst
- Network Analyst
- Tracking Analyst
- Survey Analyst
- Business Analyst
- Military Analyst
Geographic Information Systems
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Adding the Spatial Analyst Extension
select Extensions from the Customize pull-down menu
Geographic Information Systems
Adding the Spatial Analyst Extension
- that will open the Extensions dialog-box
make sure the
Spatial Analyst
box is checked
Geographic Information Systems
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Adding the Spatial Analyst Extension
- select Spatial Analyst from the Customize > Toolbars menu
- once selected, that will activate
the Spatial Analyst toobar
Geographic Information Systems
Spatial Analyst
- access Spatial Analyst tools in
ArcToolbox
Geographic Information Systems
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Spatial Analyst
Distance tools
Euclidian tools:
- used to create a continuous raster
distance, direction and allocation surface
from either point, line or polygon features
Geographic Information Systems
Spatial Analyst
Density tools
- used to create a continuous
raster density surface from
either point or line features
Geographic Information Systems
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Spatial Analyst
Interpolation tools
- IDW
- Kriging
- Spline
-Topo to Raster
- used to interpolate a surface from sample
points or contour lines
Geographic Information Systems
Spatial Analyst
Surface Analysis tools
- Aspect
- Contour
- Hillshade
- Slope
- Viewshed
Geographic Information Systems
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