GUS: 0262 Fundamentals of GIS

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GUS 0262Fundamentals of GIS

• Lecture Presentation 7
• Raster Operations
• Jeremy Mennis
• Department of Geography and Urban Studies
• Temple University

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Map Algebra and Cartographic Modeling

• A raster modeling language, and an approach to
  GIS analysis design, developed by J.K. Berry and
  C. Dana Tomlin in the late 1970s - early 1980s.
• It now forms the basis for grid-based analysis in
  ArcInfo (GRID and Spatial Analyst) and other GIS
  packages.

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Cartographic Modeling

• The representation of a geographic domain through
  a set of raster data layers.
• Tools for manipulating and transforming those
  data layers (map algebra).
• Conventions for designing and documenting models
  that integrate and relate various data layers.
• Structures to provide program control in the
  development of those models.

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Map Algebra

• A set of formally defined manipulations on raster
  data.
• Operations Fundamental mathematical and logical
  operations on raster data
• Functions Complex combinations of operations

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Functions Types
Higher order data manipulations on raster grids
built from the more basic operators. Local
compute on single-cell basis Focal compute on a
neighborhood Zonal use zones derived from a
separate grid for evaluation
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Functions Local Multiple Values
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Functions Local - Mean
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Functions Focal Immediate Neighborhood
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Functions Focal MajorityMinMean
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Functions Zonal Entire Zones
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Functions Zonal - Max
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Classification

• Raster reclassification land cover

1 grain crops 2 orchards 3 residential 4
commercial
1 agricultural 2 non-agricultural
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Classification

• Raster reclassification temperature (interval)

Grid cell value temperature (F)
1 31 - 40 2 41 - 50 3 51 - 60
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Buffer

• raster surface of within/not within proximity

Reclassify 1 within 1 unit 0 not
within 1 unit
Spread operation from buffered feature (0)
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Raster Overlay
Daily high temperature
Daily high humidity
Hot Humid Index


0 - very low 1 - low 2 - medium
3 - high 4 - very high
0 - mild 1 - warm 2 - hot
0 - not humid 1 - semi humid 2 - very humid
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Raster Overlay

• can use addition, multiplication, etc.
• can weight certain data layers
• can use any number of data layers
• cant use nominal data unless it used as
  inclusionary/exclusionary by reclassification!
• Be careful with ordinal data - classification
  impacts the results of overlay!
• Standardize interval/ratio data

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Program Control Statements and Programs
Statement notation to represent operations and
functions e.g. NEWLAYER LocalFUNCTION of
FIRSTLAYER and SECONDLAYER Program notation to
represent a procedure i.e. a sequence of
statements in which each statement operates on
the result of a previous statement
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Program Control Programs
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Program Control Programs
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Program Control Programs
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Cartographic Modeling in ArcInfo ModelBuilder
Locating Suitable Sites for a Waste Dump
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Cartographic Modeling in ArcInfo ModelBuilder
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Cartographic Modeling in ArcInfo ModelBuilder
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Cartographic Modeling in ArcInfo ModelBuilder
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Cartographic Modeling in ArcInfo ModelBuilder
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Cartographic Modeling in ArcInfo ModelBuilder