Time, Change and Habits in Geospatial-Temporal Information Standards

®
Time, Change and Habits in
Geospatial-Temporal Information
Standards
George Percivall
OGC Chief Engineer
11th International Conference on Hydroinfromatics
HIC 2014 – 2014-08-19
Copyright © 2014 Open Geospatial Consortium

Time, Change and Habits in Geospatial-
OGC®
Temporal Information Standards
• Time and change are fundamental to our scientific
understanding of the world
• Standards: means by which we construct realities (Busch)
– Tacit or formal agreement is needed among users, software
developers and institutions managing the information
– Standards from ISO, WMO, ITU, ICSU and OGC
– General talk with direct applicability to hydrology
• A robust framework for geospatial-temporal information is
now coming into place
– Newly established OGC Temporal domain working group.

A little Physics and Philosophy of Time
• Philosopher Immanuel Kant
– “Time is not an empirical exposition.
– “For neither co-existence nor succession would be perceived by us,
if the representation of time did not exist as foundation a priori”
• Physicist Lee Smolin
– “Time and its passage are fundamental and real.”
– “Hopes and beliefs about timeless truths and timeless realms are
mythology”
• Organization of this talk
1. Temporal coordinate systems for arranging events and change
2. Events and Change observations connected by causal relations
OGC®

Agenda – GeoSpatial Temporal Standards
• Temporal Coordinate Systems
• Moving Features
• Fluid Earth Coverages
• Visualizing maps and events over time
• Events and Time Series
• Process models and the Model Web
• Emergence of forms and habits
OGC®

OGC®
Temporal Coordinate Systems
• Historically, time for geographic features treated as
thematic feature attributes, i.e., independent of space.
• ISO 19108: Geographic information -- Temporal schema,
– Feature can be represented as a spatiotemporal object.
– Path of a moving object as a curve with coordinates in x, y and t
• ISO 8601: Representation of dates and times
– Represent dates: YYYY-MM-DD in Gregorian calendar
– Times in UTC
• Julian Dates as alternative to Gregorian Calendar
• ITU TF.686-3 to define Coordinated Universal Time (UTC)
– time interval of “second” in SI Units

OGC Temporal Coordinate Reference URIs
• Temporal CRS
– Temporal Coordinate System (CS)
• one single axis with Unit of Measure (UoM), label, direction [future|past]
– Temporal datum
• Binds relative temporal axis to fixed point in time
• Origin element, a date+time concatenation – ex: “2012-12-21T00:00”
• OGC policy for temporal coordinate reference system
definitions in OGC Standards
– Specifies construction and http URIs for temporal CRSs
– Such coordinate reference systems could be compound with
geospatial ones, to build spatiotemporal geometric spaces
– Vote to adopt policy scheduled to close on 2014-08-28
OGC®

Moving features in a temporal CRS
• Prism: leaf and
trajectory (sweep) in
spatio-temporal
space
• Leaf: snapshot of a
moving feature at a
time
OGC®
time
Spatial
plane
1 prism = 1 leaf + 1 sweep
(&attribute)
End leaf of tracks
id=1
Id=2
11:11:20.835 11:11:26.215 11:11:28.021 11:11:30.127
(C)
(B)
(D)
(A)
ISO19141 a basis for OGC Moving Features Standard

OGC®
Moving Features
• Geographic features whose locations change over time.
– ISO 19141 Geographic information - Schema for moving features
– Trajectory: curve that represents the path of a point in the geometry
of the moving feature
– Only “rigid” moving features that do not deform
• OGC Moving Features Standard Working Group
– Implementation standard to be based on conceptual 19141.
– CSV for encoding lightweight data records i.e. for applications
involving large data volumes and real-time response
– GML for Moving Features to encode more complex spatial
information.

OGC®
Geographic Coverages
• Geographic phenomena fall into two broad categories —
discrete features and continuous coverages
• Schema for coverage geometry and functions
– OGC Abstract Spec for Coverages; adopted as ISO 19123.
• Web Coverage Service (WCS)
– OGC web-based interface for access to coverages
– Multi-dimensional coverage data for access over the Internet.
• netCDF encoding standard
– OGC encoding of digital geospatial information representing
space/time-varying phenomena
– An extension of WCS was developed for netCDF

“A coverage is a feature that associates positions within a bounded
That is to say -- a collection of features that share a common regular
geometry
OGC®
Coverages
space to feature attribute values”
Copyright (c) 2009 Opengeospatial Consortium
• Examples
– Raster image
– Polygon overlay
– Digital elevation matrix
Latitude -->
Longitude -->

OGC®
Slide Source: Ben Domenico
Grids and Station Observations

Coverages applied to Fluid Earth Systems
• GALEON: Geo-interface for Air, Land, Earth, Oceans
NetCDF Interoperability Experiment
– Interoperability between GIS data and Fluid Earth Systems (FES),
– Parameters (e.g., pressure, temperature, wind speed) as continuous
functions in 4-dimensional space and time
– Behavior of parameters governed by partial differential equations
• CF-netCDF Core and Extensions Primer
– Climate and Forecast (CF) conventions provide semantics
– Naming conventions for files, dimension and variable names
– Geospatial and temporal coordinates, coordinate systems and
projections
OGC®

NetCDF-CF dataset content
OGC® 13
Slide Source: Stefano Nativi, Ben Domenico

Visualizing maps and events over time
• WMS with Time-Dependent or Elevation-Dependent Data –
an OGC Best Practice
• Use of dimensions time and elevation in WMS standard
• Use of a newly defined dimension reference_time
– time axis for some relevant referent time other than validity time
– E.g. start times of numerical weather calculations or sending times
of warnings
OGC®

• Validity Time of Forecasts: Range
• Nominal Start Time of Forecast: Point
Nominal Start Time 00-12 12-00 00-12 12-00 00-12 12-00
2009-11-26T00:00 * * * *
2009-11-26T12:00 * * * *
2009-11-27T00:00 * * * *
OGC®
2-D Time axis for Forecast Data
Validity Time of Forecasts
2009-11-26 2009-11-27 2009-11-28
Table from OGC Document 12-111r1

Climate Challenge Integration Plugfest
• Demonstrated standards-based
interoperability between applications
for Climate Change analysis
• Plugfest launched at FOSS4G
– But participation was welcomed from all
whether open or proprietary
OGC®
• Network of online data services
(WCS, WFS, SOS), online analysis
services (WPS, WCPS, WMS), and
geospatial client applications that
exercise those services
http://www.opengeospatial.org/projects/initiatives/ccip2009

Climate Challenge Integration Plugfest
OGC®

OGC®
Change of focus:
from Coordinate Systems to Change
• Coordinate systems – while unreal – are useful for ordering
– Spatial coordinate systems are used to identify location of objects
and to define spatial relations
– Temporal coordinate systems (time) is used to order events and
measure time between events
• Calendars and Clocks are anchored with real Events
• Change is a phenomena of interest.
– Capture change as events
– Model change as processes
Second half of talk focuses on Events and Processes

OGC®
Events
• Event: action that occurs at an instant or over an interval of time (GML)
– Snapshot: status of the whole at a moment.
– TimeSlice: only feature properties that have changed
– History: sequence of events of an object
• Event: anything that happens or is contemplated as happening at an
instant or over an interval of time (Sensor Web Enablement)
– SWE event service: provides notification of events, i.e., changes, to clients
subscribed to an event type.
– Event Service applicable across OGC web service standards standards
• Event enable WFS and a standalone Sensor Event Service in OGC Testbed 10
• Event definitions treat temporal characteristics as fundamental; spatial
characteristics are not inherent to events
– In contrast to homogeneity of 4D space of co-equal spatial reference
systems and temporal reference systems

OGC®
Events and Observations
• Observation: an act associated with a discrete time instant
or period through which a number, term or other symbol is
assigned to a phenomenon (O&M 2013)
– Act of Observation assigns a value to a property of a feature.
– If the property is non-constant, the value is a function or coverage.
• WaterML2.0
– Implementation of Observations for hydrological observations
– The core aspect of the model is in the correct, precise description of
time series.
– For exchange of time series with appropriate metadata to allow
correct machine interpretation and further analysis

class Figure 2: Observ ation Core
«FeatureT ype»
OM_Process
1 +procedure
ProcessUsed
«FeatureT ype»
OM_Observ ation
+ parameter: NamedValue [0..*]
+ phenomenonTime: TM_Object
+ resultTime: TM_Instant
+ validTime: TM_Period [0..1]
+ resultQuality: DQ_Element [0..*]
constraints
+metadata 0..1
{observedProperty shall be a phenomenon
associated with the type of the feature of interest}
{procedure shall be suitable for observedProperty}
{result type shall be suitable for observedProperty}
{a parameter.name shall not be used more than
once}
«instanceOf»
«FeatureT yp...
GFI_Feature
«T ype»
GFI_PropertyType
Domain
1
Range
+theGF_FeatureType 1
OGC®
MD_Metadata
«type»
Any
{root}
«metaclass»
GF_FeatureType
{root}
«metaclass»
GF_PropertyType
{root}
«DataT ype»
NamedValue
+ name: GenericName
+ value: Any
Observ ationContext
+ role: GenericName
Phenomenon
+observedProperty
1
+propertyValueProvider
0..*
+featureOfInterest
0..*
+relatedObservation
0..*
+generatedObservation
0..*
Metadata
«instanceOf»
+result
+carrierOfCharacteristics
0..*
WaterML2 Part 1: Time series data

OGC/WMO Hydrology Domain Working Group
4-Year International Effort – WaterML
Hydrology Domain Working Group formed
OGC at WMO Commission for Hydrology
November 2009
A time series for one variable at one location
Technical Meetings Each 3 Months
Four Interoperability Experiments
(Surface water, groundwater, forecasting)
Annual week-long workshops
Involvement by many countries
Acknowledgements: OGC, WMO, GRDC, NWS,
CUAHSI, BoM/CSIRO, USGS, GSC, Kisters, …….
2008 2009 2010 2011 2012

International Standardization of WaterML
• Hydrology Domain Working Group
– standards for water data: WaterML 2.0 suite
– organizing Interoperability Experiments (IEs)
focused on different sub-domains of water
• Chairs:
– Ilya Zaslavsky (USA)
– Tony Boston (Australia)
– Silvano Pecora (Italy)
OGC®
Iterative Development
http://external.opengis.org/twiki_public/bin/view/HydrologyDWG/WebHome

HydroDWG: Suite of Water Information Standards
OGC®
WaterML2Part5:
River Channel
(RiverML, under
development)
WaterML2Part1:
Water Quantity
Observation
(OGC10-126r4)
WaterML2Part2:
Gauging
Observation
(OGC13-021rX)
WaterML2Part3:
Water Quality
Observation
(OGC14-003rX)
CSML3:
Atmospheric-water
component
SoilML:
Soil-water
component
WaterML2Part4:
Groundwater
(GWML2, under
development)
TimeSeriesML
(under
development) Suite of Water Information Standards:
towards the identification, observation
and representation of hydrologic
features using standards
HY_Features,
common hydrologic
feature model
(OGC11-039r3)

OGC®
Process Models
• Events captured from the past and predicted for the future.
– We perceive passage of time; an arrow from the past to the future.
– Spacetime “incorporates ever more events, ‘concretizing’ as time
evolves: time progresses, events take place and history is shaped”
(Ellis 2013)
• Predict future events using models
– Models estimate some phenomena while ignoring most of the world
– “All models are wrong, some are useful” (Box 1987)
• Lets look at some standards for interfaces to models

What is the OpenMI?
• An interface standard (API) for:
• run time (in memory) data exchange between
models, databases & other components
• Whose purpose is to:
• improve ability to model complex scenarios
Application
User interface
Input data
Hydraulics
Output data
Application
User interface
Input data
Rainfall/Runoff
Output data
OpenMI
28

Linking modelled quantities
Rainfall Runoff Model River Model
Accepts Provides
Rainfall
(mm)
Runoff
(m3/s)
Temperature
(Deg C)
Evaporation
(mm)
Accepts Provides
Upstream Inflow
(m3/s)
Outflow
(m3/s)
Lateral inflow
(m3/s)
Abstractions
(m3/s)
Discharges
(m3/s)

What?
When? Where?
10:00 12:30
1.0 1.0
1.0
1.5
1.0
1.0
1.2
1.1
1.2
1.0
e1
e2
e3
e4
e5
t1 t2
The data model
30

Current status of OpenMI
• OpenMI 2.0 available and in use since 2010
http://sourceforge.net/projects/openmi/files/Version_2.0.0.0/
• OpenMI 2.0 submitted to OGC for acceptance
– Approval Date: 2013-12-06
– Publication Date: 2014-05-26
• http://www.opengeospatial.org/standards/openmi
– Document 11-014r3
31

OGC®
WPS access to Models
• OGC Web Processing Service (WPS)
– Protocol for web-based control of algorithms, handling variety of
input and output formats
– Multiple applications of WPS for access to predictive models
• WPS access to hydrologic models
– USGS Geo Data Portal processing services available using WPS
– enviroGRIDS integrated WPS with GreenLand for web access to
hydrologic modeling and land cover/land use analysis
– WPS protocol within HydroModeler environment, built on OpenMI
(Castronova 2013)
– “Towards a Geoprocessing Web” using WPS – an entire Volume of
Computers & Geosciences

OGC®
Slide source: Fei Liu, NOAA ESII @
GEOSS Future Products Workshop, March 2013

Model Interoperability - An Evolution
(Source: S. Nativi, CNR, GEOSS Future Products Workshop)
OpenMI
ESMF

Model Web and Sensor Web in GEOSS
Societal
Benefits
Decision Support
Assessments
Sensor Web
• Remotely-sensed
• In situ
Policy
Decisions
On-going feedback to optimize value and reduce gaps
Model Web
• Oceans
• Ice
• Land
• Atmosphere
• Solid Earth
• Biosphere
Interoperability
and standards

OGC®
Models without Equations
• “All models are wrong, and increasingly you can succeed
without them” (P. Norvig, Google)
– Parameterized models being replaced by large databases of
unstructured information
• Steps of Model Building (Gupta and Nearing 2014)
1. Process Model: conceptual representation, physical principles
2. Parameterized Model: system parameterization, e.g., PDEs
3. Computational Model: numerical interpolation and integration
– Generate input-state-output simulations without explicitly using
strong parameterizations (equations)?
• Model interoperability based on Process Model only?
– Focusing on the emergent forms

OGC®
Emergence of forms
• Current state of Spatial-temporal modeling
– Moving features limited to non-deforming shapes with semantic
meaning defined in advance
– Grid-based coverages over time are without semantically identified
shapes
• How do semantically significant forms emerge over time?
– Complexity is improbable. It requires explanation. Sequence which
implies a strong ordering of events in time. (L. Smolin)
– Are there general principles that guide the emergence of forms
across all geospatial-temporal processes?
• Charles Peirce: All things have a tendency to take habits.
– For every conceivable real object, there is a greater probability of
acting as on a former like occasion than otherwise.
– This tendency itself constitutes a regularity

Time, Change and Habits in Geospatial-
OGC®
Temporal Information Standards
• Coordinated framework for geospatial-temporal standards
now coming into place
• OGC Temporal Working Group
– Time as a first-class alignment concept with that of space
– Coordinate with other OGC WGs and stakeholder groups
– Open to non-members and OGC members
– http://www.opengeospatial.org/projects/groups/temporaldwg
• Heraclitus
– “The river where you set your foot just now is gone – those waters
gave way to this, now this.” (Fragment B41)

Time, Change and Habits in Geospatial-Temporal Information Standards

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