Sep' 2122, 2006

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v
Sep. 21-22, 2006
FME Worldwide User Conference - Vancouver
Validation of Spatial Networks using FME Mark
Stoakes, Safe Software
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Validation of Spatial Networks

• National Research CanadaCenter for Topographic
  Information
• Responsible for
• National Hydrological Network
• National Road Network
• and others
• Maintains the -
• Geospatial Database (GDB)
• NHN, NRN, etc.
• Geospatial Database Catalogue
• Description of the GDB and the spatial
  relationships for the network (HTML XML)

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Geospatial Database Catalogue

• Full definition of the network GDB
• feature classes (class code)
• sub-classes (sub-class code)
• geometries (geometry code)
• attributes
• Spatial relationships between feature classes
• Available in both HTML XML documents

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NRCan NHN GDB
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Components of Spatial Constraint

• Topological operator
• Spatial relationship to be validated
• DISJOINT, TOUCHES, TOUCHES TANGENT, WITHIN,
  etc.
• or an Eigenhoffer mask a.relation (b,
  ,F,')
• Cardinality
• The minimum and maximum number of intersections
  authorized between two geometries
• GDB code
• The GDB code of the class in relation to the
  element to be validated.
• Relation with multiple features

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Spatial Relationships
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FME Validation ProcessKey Steps
Read BASE features (ArcSDEQuerier)
Tests Spatial predicate Cardinality AND/OR
relation
ArcSDE Query
Test Spatial Relationship (SpatialRelator)
Error Tables
Read XML Rules
FAIL
Read CANDIDATE features (ArcSDEQuerier)
PASS
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Validation Workspace
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Validation Issues

• Tolerance testing
• tolerance tests alter the the spatial predicate
• i.e. TOUCHES ? INTERSECTS
• DISJOINT predicate
• SpatialRelator does not test for DISJOINT
• Used INTERSECTS instead and the invert the
  results
• Data Volume
• Multiple queries for the CANDIDATE features
• ArcSDE WHERE
• Queries all the tables very inefficient queries
• FME list attributes
• TCL used to enhance the existing list
  transformersListAppend, subListSearchReplace,
  subListDuplicateRemover,subListPromoter,
  RangeTester