Spatial Data and Database Concepts

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Spatial Data and Database Concepts

• GIScience
• gIs

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Data

• Surrogate for reality is numbers
• 80 of doing GIS is developing data
• Information processed data
• Relevant, reliable, accurate, verifiable,
  up-to-date, timely, complete, intelligible,
  consistent, convenient, easy to handle, protected
• Information systems changes data to info
• Conversion format
• Organization database management
• Structuring software applications
• Modeling statistical analysis, visualization

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Issues related to geographic information

• Rich and voluminous
• Complexity of earths surface
• Essential for many activities
• Level of detail varies geographically
• Multidisciplinary
• Unanticipated consequences on society

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Data types

• Primary vs secondary
• Quantitative/qualitative
• Cross-sectional vs time series
• Hard vs soft
• Categorical vs continuous
• Geographical data
• Spatially referenced
• Aggregation of space
• May be related to aspatial (nonspatial)
  attributes

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Aspatial data

• Attributes items, fields
• Record group of related items to same location
• File set of records
• Array, Table, List, Tree
• Relationships
• One to one
• Many to one
• Many to Many

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Aspatial data formats

• Flat files/Spreadsheets
• Fields and records
• Hierarchical files
• One to many relationship
• Key fields
• Relational files
• Links
• SQL structured query language

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Data models

• Field-based
• Continuous, surfaces, raster
• Indirectly obtained
• Object-based
• Feature, object, vector, discrete
• Field surveying, lab methods

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Data structures

• Feature data structures
• Geometric
• EX Shapefiles on the fly topology
• Planar enforcement
• Topological data structure
• EX Coverages are-node topology
• Directionality
• Networks
• Node (junctions) and lines (edges), flow
  direction
• Geometric coincidence
• Field data structure
• Surface
• z values
• EX DEM
• TIN (Triangulated Irregular Network)
• Object-oriented data structure
• State of feature (what is it?) and behavior (what
  it does)
• Rules and relationships
• EX Geodatabases

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Data formats

• Raster file formats
• Feature data formats (Vector, Geodatabases)
• Refer to tables.
• Data in the computer
• Bits, bytes, integers, floating points

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Data in ArcGIS

• ArcCatalog
• Create tables, access properties of fields, view
  other existing tables, database management
• ArcMap
• Work with existing tables
• Viewing and editing tables
• Field types integer, float (short real), double
  (long real), text, blob (binary large object)
• Precision total number of digits
• Scale total number of decimal places

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Categorical relationships

• Nominal
• Names, categories
• Ordinal
• Ranking
• Interval
• Numeric scales with arbitrary datum
• Ratio
• Measure of definable quantity from an absolute
  datum

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Spatial relationships

• Association of different features in space
• Absolute and relative locations
• Distance between features
• Proximity of features
• Features in a neighborhood of other features
• Direction and movement from place to place

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Determine spatial relationships by

• Boolean relationships
• And, or, inside, outside, intersecting,
  non-intersecting
• Topology
• Spatial relationships and integrity rules
• Equals, Contains, Within, Crosses, Overlaps,
  Touches
• Attribute domains
• Spatial indexing