Spatial Analysis

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Spatial Analysis
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Interacting w/a GIS VisuallyVisualization of
Attributes
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Visualizaton of Attributes cont.
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Other Interactions with GISSpatial Analysis

• answer questions, support decisions, and reveal
  patterns

• all of the transformations, manipulations, and
  methods
• Data ----gt Information ---gt Understanding
• "a set of methods whose results change when the
  locations of the objects being analyzed change"

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Which is Spatial Analysis?

• calculating the average income for a group of
  people?
• calculating the center of the United States
  population?

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Types of Spatial Analysis

• Queries and reasoning
• Measurements
• Aspects of geographic data, length, area, etc.
• Transformations
• New data, raster to vector, geometric rules
• Descriptive summaries
• Essence of data in 1 or 2 parameters
• Optimization - ideal locations, routes
• Hypothesis testing - sample to entire pop.

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Spatial Query and RetrievalGateway to Spatial
Analysis

• Overlay as a spatial query operation that is
  equivalent to an attribute join.
• Buffering as a spatial query and retrieval around
  points, lines, or areas based on distance.

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Types of overlay operations

• Union
• Intersect
• Identity
• Max
• Min
• Etc.

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Union

• computes the geometric intersection of two
  polygon coverages. All polygons from both
  coverages will be split at their intersections
  and preserved in the output coverage.

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Intersect

• computes the geometric intersection of two
  coverages. Only those features in the area common
  to both coverages will be preserved in the output
  coverage.

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Identity

• computes the geometric intersection of two
  coverages. All features of the input coverage,
  as well as those features of the identity
  coverage that overlap the input coverage, are
  preserved in the output coverage.

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Buffer
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Complex Retrieval Map Algebra

• Combinations of spatial and attribute queries can
  build some complex and powerful GIS operations,
  such as weighting.
• Weighted overlay analysis really just complex
• retrieval.

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Map Algebra
Map Algebra
Combined with
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Recode
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Spatial Analysis Handout

• On course web site
• Recoding
• Overlays (additive, partial, weighted)
• Buffering
• Map Algebra
• Clipping and Masking