timeLength, duration, timeInterval, TimeUnitType

Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 157 element ref=gml:duration element ref=gml:timeInterval choice group Its content model is a choice of two property elements: element name=duration type=duration gml:duration conforms to the ISO 8601 syntax for temporal length as implemented by the XML Schema duration type. The other alternative is gml:timeInterval which conforms to ISOIEC 11404 which is based on floating point values for temporal length. element name=timeInterval type=gml:TimeIntervalLengthType complexType name=TimeIntervalLengthType final=all simpleContent extension base=decimal attribute name=unit type=gml:TimeUnitType use=required attribute name=radix type=positiveInteger attribute name=factor type=integer extension simpleContent complexType ISOIEC 11404 syntax specifies the use of a positiveInteger together with appropriate values for radix and factor. The resolution of the time interval is to one radix -factor of the specified time unit. EXAMPLE unit=second, radix=10, factor=3 specifies a resolution of milliseconds The value of the unit is either selected from the units for time intervals from ISO 80000-3, or is another suitable unit. The encoding is defined for GML in gml:TimeUnitType: simpleType name=TimeUnitType union simpleType restriction base=string enumeration value=year enumeration value=month enumeration value=day enumeration value=hour enumeration value=minute enumeration value=second restriction simpleType simpleType restriction base=string pattern value=other:\w{2,} restriction simpleType union simpleType The second component of this union type provides a method for indicating time units other than the six standard units given in the enumeration. EXAMPLE To express a period length of 5 days, 14 hours and 30 minutes, any of the following instances are acceptable: durationP5DT14H30Mduration 158 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. timeInterval unit=―hour‖ radix=―10‖ factor=―0‖134.5timeInterval timeInterval unit=―other:week‖ radix=―10‖ factor=―0‖ 0.800595timeInterval

14.3 Temporal topology schema

14.3.1 Introduction

Temporal topology is described in terms of time complexes, nodes, and edges, and the connectivity between these. Temporal topology does not directly provide information about temporal position. It is used in the case of describing a lineage or a history e.g. a family tree expressing evolution of species, an ecological cycle, a lineage of lands or buildings, or a history of separation and merger of administrative boundaries. The following subclause specifies the temporal topology as temporal characteristics of features in compliance with ISO 19108. 14.3.2 Temporal topology objects 14.3.2.1 Overview A temporal topology object shall be a temporal element that describes the order of features or feature properties as temporal characteristics of features. The two temporal topology objects are primitive and complex. As time is a one dimensional topological space, temporal topology primitives shall be a time node corresponding to an instant, and a time edge corresponding to a period. A time node is an abstraction of an event that happened at a certain instant as a start or an end of one or more states. A state is a condition — a characteristic of a feature or data set that persists for a period. A ―static feature‖ in this International Standard means a feature that holds a consistent identifier during its life span. Time edge is an abstraction of a state, and associates with time nodes representing its start and end. However, temporal topology primit ives do not directly indicate ―when‖ or ―how long.‖ A time node need not be a start or an end of a time edge in the case of describing the event not associating with states. Such a node is called an isolated node. A topology complex is a collection of topological primitives that is closed under the boundary operation. A temporal topology complex shall be a connected acyclic directed graph composed of time edges and time nodes. A minimum temporal topology complex is a time edge with two time nodes at its both ends. EXAMPLE A lifecycle of a building can be described as a sequence of stages: plan, designing, construction, utilization, disposal and demolition. Each stage can be represented as a time edge. The boundary of each stage describing as a time node represents an event of decision-making, which terminates the stage and also originates the next stage. Thus, a lifecycle of a building is described as a temporal topology complex composed of a sequence of time edges connected with time nodes.

14.3.2.2 AbstractTimeTopologyPrimitive

Temporal topology primitives shall imply the ordering information between features or feature properties. The temporal connection of features can be examined if they have temporal topology primitives as values of their properties. Usually, an instantaneous feature associates with a time node, and a static feature associates with a time edge. A feature with both modes associates with the temporal topology primitive: a supertype of time nodes and time edges. gml:TimeTopologyPrimitive implements ISO 19108 TM_TopologicalPrimitive see D.2.5.6 and ISO 19108:2002, 5.2.4.2 and acts as the head of a substitution group for temporal topology primitives. It is defined in the schema as follows: element name=AbstractTimeTopologyPrimitive type=gml:AbstractTimeTopologyPrimitiveType abstract=true substitutionGroup=gml:AbstractTimePrimitive gml:AbstractTimeTopologyPrimitive may be used in any position that a gml:AbstractTimePrimitive is valid. Its content model is defined as follows: Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 159 complexType name=AbstractTimeTopologyPrimitiveType abstract=true complexContent extension base=gml:AbstractTimePrimitiveType sequence element name=complex type=gml:ReferenceType minOccurs=0 sequence extension complexContent complexType A topological primitive is always connected to one or more other topological primitives, and is, therefore, always a member of a topology complex. In a GML instance, this will often be indicated by the primitives being described by elements that are descendents of an element describing a complex. However, in order to support the case where a temporal topology primitive is described in another context, the optional gml:complex property is provided, which carries a reference to the parent temporal topology complex.

14.3.2.3 TimeTopologyPrimitivePropertyType

gml:TimeTopologyPrimitivePropertyType provides for associating a gml:AbstractTimeTopologyPrimitive with an object: complexType name=TimeTopologyPrimitivePropertyType sequence minOccurs=0 element ref=gml:AbstractTimeTopologyPrimitive sequence attributeGroup ref=gml:AssociationAttributeGroup attributeGroup ref=gml:OwnershipAttributeGroup complexType

14.3.2.4 TimeTopologyComplex

A temporal topology complex shall be the connected acyclic directed graph composed of temporal topology primitives, i.e. time nodes and time edges. Because a time edge may not exist without two time nodes on its boundaries, static features have time edges from a temporal topology complex as the values of their temporal properties, regardless of explicit declarations. A temporal topology complex expresses a linear or a non-linear graph. A temporal linear graph, composed of a sequence of time edges, provides a lineage described only by ―substitution‖ of feature instances or feature element values. A time node as the start or the end of the graph connects with at least one time edge. A time node other than the start and the end shall connect to at least two time edges: one of starting from the node, and another ending at the node. gml:TimeTopologyComplex implements ISO 19108 TM_TopologicalComplex see D.2.5.6 and ISO 19108:2002, 5.2.4.5 and is declared as follows: element name=TimeTopologyComplex type=gml:TimeTopologyComplexType substitutionGroup=gml:AbstractTimeComplex gml:TimeTopologyComplex may be used in any position that a gml:AbstractTimeComplex is valid. Its content model is defined as follows: complexType name=TimeTopologyComplexType abstract=true complexContent extension base=gml:AbstractTimeComplexType sequence element name=primitive type=gml:TimeTopologyPrimitivePropertyType maxOccurs=unbounded sequence