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Space and Time Topics for the

W3C Workshop on Data Models for Transportation

George PercivallCTO, Chief Engineer

Open Geospatial Consortiumpercivall@ogc.org

OGC®

Space and Time for W3C Transportation Data

● Spatial Data on the Web - Best Practices● Sensors, Observations and Measurements● Moving Objects

Additional Topics• Coordinate Reference Systems• Discrete Global Grids• Road Geometry

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Spatial Data on the Web Best Practices

https://www.w3.org/TR/sdw-bp/

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Best Practice - Spatial Data

▪ Use spatial data encodings that match your target audience▪ Provide geometries on the Web in a usable way▪ Provide geometries on the Web at the right level of accuracy,

precision, and size▪ Choose coordinate reference systems to suit your user’s

applications▪ State how coordinate values are encoded▪ Describe relative positioning▪ Include spatial metadata in dataset metadata▪ Describe the positional accuracy of spatial data

OGC®

Coordinate Reference Systems

• Coordinate– one of a sequence of N numbers

designating the position of a point in N-dimensional space

• Coordinate Systems– Cartesian 2D and 3D– Spherical (3D), Polar (2D)– Cylindrical– Linear - along a path– Ellipsoidal

• Coordinate Reference System– coordinate system related to

real world by a datum• Examples

– Geographic– Geocentric– Vertical – Engineering – Image – Temporal– Derived CRS, e.g., projections

Reference ISO 19111 and OGC Abstract Spec Topic 2

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Time Ontology in OWL

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Allen Temporal Interval Algebra

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Semantic Sensor Network Ontology

https://www.w3.org/TR/vocab-ssn/ https://portal.opengeospatial.org/files/74883

Relationships between - sensors/ actuators/ sampling and - observations/ actuations/samplings

Modular architecture supports judicious use of "just enough" semantics for diverse applications.

An OWL-2 DL ontology

Aligned with OGC/ISO Observations and Measurements

OGC®

Observations and Measurements

9

• OGC SWE* defines Observations, relevant entities, and their relationships

• Syntactic interoperability and Semantic interoperability

*OGC Sensor Web Enablement (SWE) Standards deployed in operational implementations for more than a decade

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Sensors and Observation

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Actuation

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OGC SensorThingsOpen, geospatial-enabled API to interconnect IoT

devices, data, and applications over the Web

Part I – Sensing (adopted)Part II – Tasking (adopted)

Part III – Rules Engine (in development)Part IV – Stateless Extension (in development)

https://www.opengeospatial.org/standards/sensorthings

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OGC SensorThings Data Model

(OGC and ISO 29156)

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Applications or Devices

OGC SensorThings

API

2. SensorThings API resource interfaces for accessing sensor data, tasking actuators and detect events

1. Standard Data Model based on ISO/OGC Observation and Measurement

MQTT, HTTP

OGC®

OGC Moving Features

• Moving features, e.g. vehicles, pedestrians, airplanes, ships• CSV, JSON, XML encodings

http://docs.opengeospatial.org/is/16-120r3/16-120r3.html

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Spatial Temporal Geometry

OGC Moving Features Standard implements ISO 19141

http://docs.opengeospatial.org/is/16-120r3/16-120r3.html

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Moving Features: one trajectory, one geometry

Operations between a trajectory object and a geometry object of which geometry is stable

time

x

y

Trajectory object

Geometry objectIntersects

Intersection

Examples:•intersects•distanceWithin•intersection

http://docs.opengeospatial.org/is/16-120r3/16-120r3.html

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Moving Features: Two trajectories

Operations between two trajectory objects from the spatio-temporal viewpoint

time

x

y

nearestApproach

distanceWithin

Examples:•distanceWithin•intersection•nearestApproach

Trajectory objecthttp://docs.opengeospatial.org/is/16-120r3/16-120r3.html

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Connected & Autonomous Vehicles

Jeremy Morley, Chief Geospatial Scientist Ordnance Survey - OGC Future Directions, Leuven, 25 June 2019

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Additional Topics

Space and Time Topics for the W3C Workshop on Data Models for Transportation

OGC®

OGC®

Discrete Global Grids

Slide source: Matthew B. J. Purss, Robert Gibb, Faramarz Samavati, Perry Peterson, Jin Ben, Roger Lott

OGC®

Analysis without Maps

• Traditional GIS and image analysis approaches assume flat earth geometries = simpler code… but data is warped to fit the “flattened” view of the Earth.– OK for local scales (where approximate Earth surface is relatively flat)

– But Fails at larger scales (where curvature of the Earth becomes significant.)

OGC®

Discrete Global Grid Systems

“…a spatial reference system that uses a hierarchical tessellation of cells to partition and address the globe. DGGS are characterized by the properties of their cell structure, geo-encoding, quantization strategy and associated mathematical functions.”

– OGC DGGS Standard

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Standardising Discrete Global Grid SystemsDifferent Cell Shapes

nD Spatial Analyses ↓

1D Array Processes

Unique Cell Indices• Hierarchy-based, Space-filling Curve, Axes-based or Encoded Address

00 01 02 03 10 11 12 13 20 21 22 23 30 31 32 33

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Simple Geometries for Simple Features

© 2016 Open Geospatial Consortium

OGC simple features (ISO 1923) geometries are restricted to 0, 1 and 2-dimensional geometric objects that exist in 2-dimensional coordinate space (R2).

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A/B A B A B A B

A B A B ABA

Equals Touches Overlaps Contains

Within Disjoint Intersects Crosses

OGC Simple Features

Topological Relations between Spatial Objects

© 2016 Open Geospatial Consortium

OGC®

•For exchanging the output of a design with someone who is likely to use the design for purposes other than completing the road design.•Road specifies that part of a Facility which is a single segment of road that is continuous, non-overlapping, and non-branching (though it may contain intersections with other roads)•Road can be represented with RoadElements, 3D StringLines, or 3D surfaces and layers, or sets of each of these•Road is dependent upon Facility and LandFeature

OGC InfraGML - Roads

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RoadCrossSection RC

•A CrossSection describes how a Road looks, in a 2D cross section view, at some specific location along its length.

•CrossSections can have CrossSectionElements and/or Areas, defined by CrossSectionPoints

•RoadCrossSection is dependent upon Road

OGC®

CityGML – Street Modeling

CityGML and Streets of New York – Proposal for Detailed Street ModellingC. Beil & T. H. Kolbe

ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume IV-4/W5, 2017 12th 3D Geoinfo Conference 2017, 26–27 October 2017, Melbourne, Australia

OGC®

Comprehensive global community-driven forward- looking expertise in location

Using location, we connect people, communities, technology and decision making to create a sustainable future for us, our kids and future generations

• By specializing in making location more Findable, Accessible, Interoperable and Reusable

• Via a proven collaborative and agile process combining standards, innovation and partnerships

Communities- Tech & Market

Domains

Partnerships & Alliances

Process for Standards & Innovation