Transcript No Slide Title

Grid-based Map Analysis Techniques
and Modeling Workshop
Fundamental Concepts, Practical Considerations, Pitfalls and Potential
“GIS Modeling is more
different than it is similar
to traditional mapping and
data analysis”
Presented by Joseph K. Berry
Berry & Associates // Spatial Information Systems
2000 S. College Ave, Suite 300, Fort Collins, CO 80525
Phone: (970) 215-0825 Email: [email protected]
…visit our Website at
www.innovativegis.com/basis
Grid-based Map Analysis Techniques and
Modeling Workshop
Part 1 – Maps as Data
Discrete objects vs. continuous geographic space
Grid data types and structures
Grid data display
Part 2– Surface Modeling
Part 3 – Spatial Data Mining
Part 4 – Spatial Analysis
Part 5 – GIS Modeling
Historical Setting and GIS Evolution
Manual map drafting …8,000 years
Computer Mapping
automates the cartographic process (70s)
Spatial Database Management
links computer mapping techniques with
traditional database capabilities (80s)
GIS Analysis and Modeling
representation of relationships within
and among mapped data (90s)
…Multimedia GIS is the current frontier (00s)
but that’s another story
(Berry)
Desktop Mapping Framework (Vector; ArcView)
Click on…
Select Theme
Zoom Pan
Info
Tool
Theme
Table
Now for a
Geo-Query…
Distance
Spatial
Table
:
Object ID
X,Y
X,Y
X,Y
:
Query
Builder
…identify tall
aspen stands
Attribute
Table
Feature
:
Object ID
:
Species
:
Aw
:
etc.
Big …over 400,000m2 (40ha)?
Discrete, irregular map features (objects)
(Berry)
MAP Analysis Framework (Raster; MapCalc)
Click on…
Zoom Pan Rotate
Display
Shading
Manager
Now for some
Map Analysis…
Grid
Analysis
…calculate a
slope map and
drape on the
elevation surface
Grid
Table
:
--, --, --, --,
--, --, --, --,
--, --, --, --,
--, 1944, --,
--, --, --, --,
:
Continuous, regular grid cells (objects)
(Berry)
Basic Grid Structure
…a Grid Map consists of a matrix of
numbers with a value indicating the
characteristic or condition at each grid cell
location—geo-registered set of Grid Layers
VECTOR —Discrete
RASTER —Continuous
Lines
Grid Map
Map Stack
Fill
Discrete Spatial Objects
vs.
Continuous Geographic
Distributions
…the Analysis Frame provides consistent “parceling” needed for map analysis
and extends POINTS, LINES and POLYGONS to SURFACES
(See Map Analysis, “Topic 18” for more information)
(Berry)
Data/Display Types
Data Types
Numerical Distribution — Nominal, Ordinal, Interval, Ratio, Binary
Geographical Distribution — Choropleth or Isopleth
Display Conditions
Display Form — 2D or 3D
Display Type — Grid or Lattice
Data Display Type — Discrete or Continuous
3D toggles between 2D and 3D
display forms
Use Cells toggles between
Lattice and Grid display types
Data Type toggles between
Discrete and Continuous data
types
(Berry)
Micro Terrain Analysis
“Map-ematics”
Calculation of slope considers
the arrangement and magnitude
of elevation differences
Characterizing Slope (and Aspect)
A digital terrain surface is formed by assigning
an elevation value to each cell in an analysis
grid. The “slant” of the terrain at any location
can be calculated– inclination of a plane fitted
to the elevation values of the immediate vicinity.
Characterizing Surface Flow
The relative amount of water passing through
each grid cell is determined by simulating a
drop of water landing in each cell and
proceeding downhill by the steepest path. The
number of paths crossing each location
identifies the total uphill confluence.
(See Map Analysis, “Topic 11” for more information)
(Berry)
Simple Erosion Model
…GIS Modeling involves logical sequencing of map
analysis operations
(Exercise #2)
…a Command
Macro Language
consists of a
graphical
interface for
entering, editing,
executing,
documenting,
storing and
retrieving a GIS
Model
Script
Logic
(Berry)
Variable-Width Buffer (Sediment loading)
But all buffer-feet are not the same…
(slope/flow Erosion_classes)
Simple Buffer
Effective Buffer for sediment loading
based on intervening conditions
Effectively far away, though
right near a stream
…how can that be?
…what about different soils?
…what about roughness?
…or time of year?
(Berry)