Presented by Joseph K. Berry Adjunct Faculty in Geosciences, Department of Geography, University of Denver Adjunct Faculty in Natural Resources, Warner College of Natural Resources, Colorado State University Principal, Berry & Associates // Spatial Information Systems Email: [email protected]— Website: www.innovativegis.com/basis There is a “map-ematics” that extends traditional math/stat concepts and procedures for the quantitative analysis of spatial data This workshop provides a fresh perspective on interdisciplinary instruction at the college level by combining the philosophy and approach of STEM with the spatial reasoning and analytical power of grid-based Map Analysis and Modeling This PowerPoint is posted at www.innovativegis.com/basis/Courses/SpatialSTEM/ SpatialSTEM: A Mathematical Structure for Understanding, Communicating and Teaching Fundamental Concepts in Spatial Reasoning, Map Analysis and Modeling Workshop Session 1 — Spatial Analysis Operations
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Presented by Joseph K. Berry Adjunct Faculty in Geosciences, Department of Geography, University of Denver Adjunct Faculty in Natural Resources, Warner.
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Presented by
Joseph K. Berry
Adjunct Faculty in Geosciences, Department of Geography, University of DenverAdjunct Faculty in Natural Resources, Warner College of Natural Resources, Colorado State University
Principal, Berry & Associates // Spatial Information Systems
Where – a Spatial Table contains X,Y coordinates delineating the location of each point, line and polygon boundaryWhat – a linked Attribute Table contains text/values indicating the classification of each spatial object
:ID#21X,YX,Y :
: :ID#21 Meadow : :
SpatialTable
AttributeTable
Where – Cell Position in the matrix determines location within a continuous, regular grid What – Cell Value in the matrix indicates the classification at that location
Vector vs. Raster Data Forms (analytical perspective)
…grid-based mapped data is “Preconditioned for AnalysisPreconditioned for Analysis” as spatial topology is inherent in the matrix(Berry)
Analysis Frame
Col 3, Row 22Col 3, Row 22
The Analysis Frame provides consistent “parceling” needed for map analysis and extends discrete Points, Lines and Polygons…
Col 1, Row 1Origin
Col 1, Row 1Origin
3D Surface(stair steps)
Grid
A Grid Map consists of a matrix of numbers with a value indicating the characteristic/condition at each grid cell location—
Raster(continuous)
Grid Data Structure (fundamental organizational concepts)
Contour Lines
Intervals
Vector (discrete)
Elevation Contour Interval
2300-2500’
Elevation Contour Interval
2300-2500’
3D Surface(gradient)
…to continuous Map Surfaces
Map Stack
Map Stack
…forming a set of geo-registered Map Layers or “Map Stack”
Data listing for aMap Stack
Drill-down
(Berry)
Exercise 1-1) Map Analysis Framework (grid-based data structure and example analysis)
Companion Materials on the Map Analysis CD-ROM
(or Flash Drive)
MapCalc Learner Installation
Note: there lots of additional materials on the CD such as additional readings, exercises, color figures, and software to include a fully
functional demo version of Surfer software a very popular and versatile package for Surface Modeling of field data and 3D graphics.
I have found that an Elevation map and the Slope operation are ideal for demonstrating grid map data structure, display and analysis capabilities—most (all?) students have a good understanding of terrain as a surface and
terrain steepness as a concept (particularly if they ski, hike or climb).
Display Tools …the following “hands-on” experience is designed to gain
familiarity with grid-based data structure and display of map surfaces
ContourLines Contour Intervals
3D Lattice
3D Grid
…pushes up each cell to its stored value (blocky)…pushes the nodes of the wireframe to the stored value (smooth)
(Berry)
Example Map Analysis …the following “hands-on” experience is designed to gain familiarity accessing map analysis operations by
calculating a Slope map from the Elevation surface that identifies a continuous surface of terrain steepness (the Spatial Derivative)
Slopemap(Spatial Derivative)
Slopemap draped over Elevation Steep
Gentle
Map Calculus (Spatial Derivative)
GIS as “Technical Tool” (Where is What) vs. “Analytical Tool” (Why, So What and What if)
Spatial Analysis extends the basic set of discrete map features (points, lines and polygons) to map surfaces that represent continuous geographic space as a set of contiguous grid cells,and thereby provides a mathematical/statistical framework for analyzing and modeling the
Contextual Spatial Relationshipswithin and among grid map layers
Basic Grid Math and Map Algebra Example (Precision Agriculture)
(Berry)
Exercise 1-2) Using Grid Math and Map Algebra Operations (calculating difference and percent change maps)
Note: other grid map surfaces for two time periods can be substituted, such as pollution levels or barometric pressure or wildlife activity or sales revenue or home values. The
objectives of the exercise is to experience visualization of surface data (map variables) and executing a simple grid math operation then extending the processing to spatially
evaluating a familiar algebraic equation—map variables are just organized sets of numbers.
There are numerous exercise “tweaking” possibilities depending on the discipline and class environment involved– we can discuss in Workshop Session 3. My only caveat is to use hypothetical data and not attempt to download
and geo-register real data (or worse, local data) unless you have considerable GIS experience.
Evaluating and Algebraic Equation …the following “hands-on” experience spatially evaluates the
standard Percent Change equation to generate a map of percent change (spatially disaggregated
solution) instead of a single change value (spatially aggregated solution)
Calculating a Difference Map …the following “hands-on” experience is designed to
demonstrate an application of a basic Grid Math operation (minus) on two map variables
…Effective Proximity relaxes the “straight line” requirement by considering intervening relative and absolute barriers to movement
…left with the modern concept of distance as the set of shortest not necessarily straight paths among locations—”Proximity Surfaces”
(Berry)
How far?
a
b
A series of wavefronts (ripples) form concentric halos of one grid space increments. This procedure extends the concept of Distance to that of Proximity
Simple Buffer– “as-the-crow-flies” proximity to the road; no absolute or relative barriers are considered; dark blue line indicates the full simple buffer reach (polygon)
Clipped Buffer– simple proximity for just the land areas
Uphill Buffer– simple proximity to the road for just the areas that are uphill from the road; absolute barrier (uphill only– absolutely no downhill steps)
Simple Proximity …the following “hands-on” exercise provides experience in calculating “simple” proximity surfaces (as the crow flies) first from a single point and then from a set lines.
…from Turnout1 to everywhere
…from Roads to everywhere
Effective Proximity …the following exercise is designed to provide experience in calculating “effective” proximity surfaces (as the crow walks).
…from Turnout1 just along roads
…hiking from Roads to
everywhere
(Berry)
Calculating Visual Connectivity (sequentially assessing the tangent)
Seen if new tangent exceeds all previous tangents along the line of sight—
Viewshed Analysis …the following exercise is designed to provide experience in calculating the Viewshed of one or more viewing locations (binary seen/not seen by at least one viewer location).
…Visual Exposure from Roads to
everywhere
Viewshed Analysis …the following exercise is designed to provide experience in calculating the Viewshed of one or more viewing locations (binary seen/not seen by at least one viewer location).