temporality and encodings

Singapore Workshop – Technical Focus - 16 June 2008

Temporality and Encodings

Concepts and Examples

Presented by Brett BrunkAeronautical Information Management (AIM) group

Federal Aviation Administration – United States


Topics

Temporality● Why is it necessary● AIXM 5 temporality concepts● A NAVAID example

Example AIXM 5 Encodings● Components of an AIXM 5 exchange file● New Airspace● Temporary change to airspace usage


Why do we need temporality?

Time is essential for aeronautical informationFor operational reasons, distinction

between:● Permanent changes● Temporary status

Two levels:● Life of the feature● Changes in properties


Temporality Model

Definition● A model that incorporates the concept of time

Key assertions● All features are temporal with start of life and end of life

● Example, A new air traffic control sector● All features change over time

● Example, A VOR is out of service for a day AIXM Temporality Model

● Relates features to the time extent in which they are valid● Provides various means to describe the time extent


Time varying properties

Time

P1

FeatureProperties

value 1 value 2 value 3 value 4

P2 value a value b

P3 value x

P4 value z

P5 value $ value #


The basic Time Slice model

Time

P1

FeatureProperties

value 1 value 2 value 3 value 4

P2 value a value b

P3 value x

P4 value z

P5 value $ value #



P1

FeatureProperties

P2

P3

P4

P5

TimeSlices: TS 1 TS 2 TS 3 TS 4 TS 5 TS 6 TS 7 TS 8



P1

FeatureProperties

P2

P3

P4

P5


states


The basic Time Slice modelUML


P1

FeatureProperties

P2

P3

P4

P5


temporaryvalue w

TS "temp”

event

Temporary events (digital NOTAM)


Temporary events

Two kinds of Time Slices● Baseline = describes the feature

state (the set of all feature’s properties) as result of a permanent change;

● Temporary Delta = describes the transitory overlay of a feature state during a temporary event.

AIXMFeature

identifier : CodeUUIDType

<<feature>>

AIXMFeatureTimeSlice

validTimeinterpretationfeatureLifetimeproperty1property2property3...

1..* +time varying properties1..*


Current status of a feature

P1

FeatureProperties

P2

P3

P4

P5


temporaryvalue w

SNAPSHOT

SNAPSHOT = describes the state of a feature at a time instant, as result of combining the actual BASELINE Time Slice valid at that time instant with all TEMPDELTA Time Slices applicable at that time instant.


P1

FeatureProperties

P2

P3

P4

P5


temporaryvalue w

TS "temp”

Permanent changes Permanent changes

event

PERMDELTA = A kind of Time Slice that describes the difference in a feature state as result of a permanent change.


P1

FeatureProperties

P2

P3

P4

P5

Time

Time Slice Types

PERMDELTA 1(start of life)

PERMDELTA 2 PERMDELTA 3PERMDELTA 4

PERMDELTA 5 PERMDELTA 6PERMDELTA 7

PERMDELTA 8PERMDELTA 9

(end of life)

TEMPDELTA

temporaryvalue w

SNAPSHOT


Summary - Time Slice types

BASELINE = A kind of Time Slice that describes the feature state (the set of all the feature’s properties) as result of a permanent change;

PERMDELTA = A kind of Time Slice that describes the difference in a feature state as result of a permanent change;

TEMPDELTA = A kind of Time Slice that describes the transitory changes of a feature state during a temporary event;

SNAPSHOT = A kind of Time Slice that describes the state of a feature at a time instant, as result of combining the actual BASELINE Time Slice valid at that time instant with all TEMPDELTA Time Slices applicable at that time instant.


An Example: Navaid frequency change

Imagine that AML Navaid undergoes an upgrade that changes its frequency from 112 MHz to 113.2 MHz…

1. Schedule permanent change to coincide with AIRAC update cycle

2. Shutdown AML before the upgrade3. Perform the upgrade4. Start AML in test mode to evaluate

change


An Example: Navaid frequency change

AML Navaid undergoes an upgrade that changes its frequency from 112.0 MHz to 113.2 MHz…


Topics

Temporality● Why is it necessary● AIXM 5 temporality concepts● A NAVAID example

Example AIXM 5 Encodings● Components of an AIXM 5 exchange file● New Airspace● Temporary change to airspace usage


AIXM is based on International Standards

Aeronautical Information Exchange Model (AIXM)

ISO 19107 Spatial

ISO 19108 Temporal

ISO 19115 Metadata ISO 19136 Geography Markup Language (GML)Universal Markup

Language (UML)

Extensible Markup Language (XML)

Conceptual standards Exchange standards


Extensible Markup Language (XML)

XML – Extensible Markup Language

● Have you looked at whatis underneath a webpage?

● XML has a similar look to HTML

Computer readable● Electronic exchange● Vendor supported

<h2><a href="sdat2/html/download.htm"> SDAT 5.7 Release</a></h2>

<h3 class="byline">New Features >></h3>

<p> <ul>

<li>Create traffic collections based on a sector number. (Flights flown through specified sector(s))</li>

…

<h2><a href="sdat2/html/download.htm"> SDAT 5.7 Release</a></h2>

<h3 class="byline">New Features >></h3>

<p> <ul>

<li>Create traffic collections based on a sector number. (Flights flown through specified sector(s))</li>

…

<RunwayDirection>

<Designator>20L</Designator>

<VFRPattern>RIGHT</VFRPattern>

</RunwayDirection>

…

<RunwayDirection>

<Designator>20L</Designator>

<VFRPattern>RIGHT</VFRPattern>

</RunwayDirection>

…

Web Page HTMLWeb Page HTML

XML DocumentXML Document


Key Concept: Geometry and GML

Geometry important property of aeronautical information

● Airspace polygons● Airport Reference Points● Navaid location


Key Concept: Geometry and GML

ISO 19136 Geography Markup Language (GML)

● Vendor independent standard

● Based on XML● Good industry adoption


Creating a new airspace

<?xml version="1.0" encoding="UTF-8" ?> <Airspace xmlns=“http://www.aixm.aero/schema/5.0” xmlns:gml="http://www.opengis.net/gml/3.2” xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:gmd="http://www.isotc211.org/2005/gmd" xmlns:gco="http://www.isotc211.org/2005/gco"

xsi:schemaLocation="http://www.aixm.aero/schema/5.0 ../xsd/AIXM_Features.xsd" gml:id="A00001">

<gml:identifier codeSpace="http://ead.eurocontrol.int">0bf9537f-27f0-4650-a75f-125006366e51</gml:identifier>

<timeSlice><AirspaceTimeSlice gml:id="VID001">…</AirspaceTimeSlice>

</timeSlice>

</Airspace>

An AIXM Airspace Feature

Unique Identifier for the Airspace. Computer readable

Container for the timeslices that make up the airspace

End of the Airspace Feature

Definition of the airspace


Creating a new airspacecontinued

<Airspace …><gml:identifier …>…</gml:identifier> <timeSlice>

<AirspaceTimeSlice gml:id="VID001"><gml:validTime>

<gml:TimePeriod gml:id="VID002"><gml:beginPosition>2006-03-15T00:00:00</gml:beginPosition><gml:endPosition indeterminatePosition="unknown" />

</gml:TimePeriod> </gml:validTime> <interpretation>BASELINE</interpretation>

<featureLifetime><gml:TimePeriod gml:id="VID003">

<gml:beginPosition>2006-03-15T00:00:00</gml:beginPosition> <gml:endPosition indeterminatePosition="unknown" /> </gml:TimePeriod> </featureLifetime>

… other properties</AirspaceTimeSlice> </timeSlice>

</Airspace>

Baseline timeslice containing all feature

properties

Period of validity for timeslice

Period of validity for the Airspace feature




<AirspaceTimeSlice gml:id="VID001">…

<type>TSA</type> <designator>EBT15</designator> <name>LO-RENINGE UAV AREA</name> <controlType>MIL</controlType> <class> <AirspaceLayerClass> <class>G</class> </AirspaceLayerClass> </class>

<geometryComponent>…</geometryComponent></AirspaceTimeSlice>

</timeSlice> </Airspace>

Airspace Feature properties

Airspace shape and volume




<AirspaceTimeSlice gml:id="VID001"> …<geometryComponent>

<AirspaceGeometryComponent><theAirspaceVolume>

<AirspaceVolume> <upperLimit uom="FL">95</upperLimit> <upperLimitReference>STD</upperLimitReference> <lowerLimit uom="FT">4500</lowerLimit> <lowerLimitReference>MSL</lowerLimitReference>

<horizontalProjection> … </horizontalProjection> </AirspaceVolume> </theAirspaceVolume> </AirspaceGeometryComponent> </geometryComponent> </AirspaceTimeSlice> </timeSlice> </Airspace>

Upper and lower limits

GML definition of horizontal boundary


Demonstration

Viewing AIXM features in a commercial product

● LuciadMap’s prototype AIXM Viewer

temporality and encodings

Documents

time instant

kind of time slice

kinds of time slicesbaseline

feature state

mhzschedule permanent

permanent changepermdelta

permanent changetempdelta

permanent changes permdelta