VRML History -- Definitions
history
The consecutive series of representations/versions
with linked version time periods one object
has during its existence (specified by its valid
period).
now
The present real time as perceived by the
user.
real time
A monotonically increasing value generated by a node. Its synonym is time
in VRML97.
time granularity
The amount of time in the valid time dimension which is used as the minimal
unit for points in time (e.g. seconds, days, years). According to the definition
of SFTime
seconds are normally used as the unit of time.
time interval
The directed duration of time with no specified starting and ending time
point.
time-invariant
A behaviour or property of an object is time-invariant or static if this
property does not change in time, i.e. only one value is valid all over
time for that property.
time period
A period of time starting at one time point and
persists until the ending time point of the period.
time point
One discrete point/instant in time which is instantaneous, i.e. has conceptually
zero duration. Normally, a time point is specified by a number since a
given time origin in a application dependent time
granularity (e.g. seconds, days, years).
time-variant
A behaviour or property of an object is time-variant if this property changes
its value during the valid period of the object.
Normally, at each time point only one value exists
for each property. There may be the case that at one time no value exists
for a property, i.e. the property does not exist at this time.
valid period
The period of time when a object exists and has one or more representations/versions.
Before the start of the valid period (object's birth) and after the end
of the valid period (object's death) the object does not exist.
valid time
Valid time concerns the time when a fact is true in reality. It is another
time dimension which is independent to "real" time.
Valid time describes the time of existence or validity of things in the
world, the time when they are, were or will be valid.
version
One representation of an object which is linked with one version
time period during the valid period of that
object.
version time period
The period of time when an object has exactly one specific representation/version
at all time points during this period. The version
time period is part of the valid period.
For questions or comments contact Hartmut
Luttermann.
Copyright © 1998-99 University of Siegen, Germany.
Last update: 1.November 1999.
http://www-winfo.uni-siegen.de/vrmlHistory/docs/partVH/glossary.html