Meta-Networks. Multi-Dimensional Real World Objects for the Next Generation Transportation Geography. March 2004

Transcription

1 Meta-Networks Multi-Dimensional Real World Objects for the Next Generation Transportation Geography presented to 2004 GIS-T T Symposium presented by John Sutton Cambridge Systematics, Inc. March 2004 Transportation leadership you can trust.

2 Inspiration Key Concepts: Transportation is a feature rich environment GIS-T network representations are simplified versions of transportation features i.e., spatial primitives (points, polylines) Transportation geography is more than GIS-T, hence the need for Meta-Network Objects Key References Multidimensional Geographic Information Science, Jonathan Raper, Taylor & Frances, 2000 Transportation: A Geographic Perspective, William R. Black, The Guildford Press, 2003

3 Meta-Network Problem Data Integration Simple Example Centerline Bus Stop Road Width Bus stop absolute location Is converted to relative location on centerline to comply with network data model

4 Network Data Models Schematic Network Graph (Links/Nodes) + Connectivity Cartographic Network Graph + Geometry (shape) + Location (geography) Geographic Network Graph + Geometry + Location + Topology (spatial intelligence) GIS-T network adds measures Network Data Models are Linear Data Management Systems and One-Dimensional

5 Why a Meta-Network? Problem of network pathologies, i.e., situations where network geometry doesn t match network topology Some examples HOV lanes/contraflow lanes/bus lanes Intersections beneath an overpass Frontage roads that run parallel to and underneath elevated highways Many others Network generalization Different descriptions of the same network features, e.g., travel model networks, corridor studies Reference: Sutton, J., Object Oriented Network Data Structures: The Road to Interoperability, GIS-T Symposium, San Diego, 1999

6 Spatial Data Interoperability Multiple formats and representations of the same features Spatial Data Domains GIS Transportation Feature Environment ( Road, Railway Airport ) Feature Types Feature Format Geometry Data Conversion Engineering Drawing Survey/Cartography/GPS Visualization/Images

7 Meta-Network Challenge Meta-Network manages location and feature description (metadata) Separate topology from geometry Corresponds feature types by location Feature Types Feature Format Geometry Spatial Data Domains GIS Transportation Feature Environment Meta-Network = Feature + Location Spatial data domains continue to manage data objects and geometry Engineering Drawing Survey/Cartography/GPS Visualization/Images

8 Meta-Network Concept Not a data model of prescribed network objects Not an edge or junction Not a centerline Not a graphic object or image Meta-Network is a real-world description of transportation features Transportation Feature (RWO) + Location Location Data Dictionary

9 Meta-Network Definitions Meta-Network Multidimensional real world transportation feature Higher-level feature object (pure spatial-mathematical construct) Multidimensional 3-D + time + history Real World Object 3-D Transportation feature (e.g., bridge, intersection) Absolute location (datum)

10 Meta-Network Schema Reality Abstraction Real World Object Polyline X 1 x 2 y 1 y 2 z 1 z 2 Graphic Location Set Image (Pixel)

11 Meta-Network Implementation Network correspondence accomplished by true location Not a Master Network concept Requires detailed description and location of each transportation feature Task equivalent to the genome project Provides the Network DNA i.e., true multidimensional location Some of it exists e.g., surveyor files and maps, but most data still needs collecting I I locate therefore I can rather than I link therefore I am

12 GIS-T Status Transformation Criteria GIS has evolved to be an influential technology in transportation, especially in planning and analysis GIS is often promoted as a data integration method as part of enterprise IT solutions including operational as well as planning databases For GIS to become a truly transformational technology it must address Meta-Network issues

13 Transportation Innovation GIS-T Innovation Early Adopters Mature Technology Transformational Influential GIS Incremental??? Modified from Geerlings and Rienstra (2003) Time

14 Conclusions GIS in transportation is an Influential technology not a Transformational technology Transportation is a rich environment which is simplified in GIS and other software For GIS to be transformational requires a re-think and rearchitecting of how to describe and integrate transportation data Meta-Networks is a concept/schema to use location as the common denominator with RWO Transportation Geography is about spatial organization of transportation features More than one-dimensional networks Need a schema like Meta-Networks to adequately describe the transportation geography environment

15 Questions?

16 How Does This Differ from Metadata? Metadata describes abstract data types Spatial primitives (polyline, point) One dimensional shapes (centerlines) Feature ID standards are related to abstract data types Meta-Network is true data not abstract data Metadata is important and can be a useful tool to translate between true and abstract data types Meta-Network Metadata Abstract data type e.g., centerline

17 Transportation Innovation Innovation Transformational Influential Incremental??? Time Modified from Geerlings and Rienstra (2003)