Validation of Spatial Networks Using FME at the 2006 Worldwide User Conference
Discover the insights shared by Mark Stoakes from Safe Software at the 2006 FME Worldwide User Conference in Vancouver. The presentation focused on the validation of spatial networks, including the National Hydrological Network and National Road Network managed by National Research Canada. Key topics included maintaining the Geospatial Database, the descriptions of feature classes, geometries, attributes, and spatial relationships. The process of validating these elements using FME tools was discussed, highlighting the importance of spatial predicates and tolerance testing for accurate data management.
Validation of Spatial Networks Using FME at the 2006 Worldwide User Conference
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Presentation Transcript
v FME Worldwide User Conference - Vancouver Sep. 21-22, 2006 Validation of Spatial Networks using FME Mark Stoakes, Safe Software
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)
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
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
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
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 transformers:ListAppend, subListSearch&Replace, subListDuplicateRemover,subListPromoter, RangeTester
