Physical resources can be located at different Locations at different Times, creating a demand for relating spatial information with time information. Indeed, having two distinct spatio-temporal pairs registered with an object, e.g., <L1; T1> and <L2; T2>, implies that the object have been moved from the first location to the second, somewhere between times T1 and T2. Initiatives exist to support semantic trajectories, that is, a route that is composed of connections between points that can originate from different sources and be represented differently, but together make up the complete trajectory that is traversed by a subject
This CP will cover both situations: First, to provide the capability to register an object at certain locations at certain moments; second, to reveal the underlying fact that the object has been moved. The first one simply ties one or more spatio-temporal pairs to an object, agnostic to the underlying movement; the second one follows up on the spatio-temporal pairs that the object is bound to and derives the geographical paths that the object was moved over in time, its so-called semantic trajectory.
Requirements
Requirement 1 - Spatio-temporal characteristics
This requirement exists in order to register a location of an object at a certain moment.
An object of interest (whether it is considered evidence or not) will be moved around throughout the investigation. This implies its location to change over time. Where the above requirements relate to a location only, this requirement considers an object to be at a certain location at a certain moment in time. No matter how much an object is being moved around, it must be clear without any doubt where the object has been at certain moment in time.
This might be related to certain events/activities that have to take place with the object, or some place it has to be stored, by protocol or ad-hoc determined.
For those events (moments in time) that are considered relevant to the investigation, it must be possible to record and retrieve the whereabouts of the object.
No assumptions are made regarding the activities/events that (have been) take(n) place.
This requirement would allow to tie, to an object, a tuple representing a spatial position and temporal moment within some pre-determined bounds of accuracy.
Despite the temporal demand that might apply for a location, it is required to explicitly maintain independence between the spatial and temporal dimensions, as opposed to conflate them into one single characteristic. This is the ratio to apply a spatio-temporal relationship<L; T>.
Whenever no time information is present about a the whenabouts of an object, we follow the open world assumption and indicate the time as unknown whilst providing the location information.
Requirement 2 - Semantic trajectory
A semantic trajectory registers the spatial movements of an object over time, explicitly acknowledging the paths in between the spatial locations that the object has been moved over during a certain time interval. The path does not need to be the exact trajectory that has been taken, although such is not excluded as well.
The trajectory is build from separate paths that exist between temporally adjacent locations that has been visited. As such, this requirement builds on CP #409;
Each location that is used to determine a path / trajectory is agnostic to how the location has been represented;
Although a path represents the notion of a route, it does only explicate the fact that the object has been moved from the first to the second location during a certain time frame; no assumptions can be made about the actual route that has been followed by the object between adjacent locations;
Because a path does not represent an actual route, and despite that each location exhibits a point in space with a certain accuracy, a path does not carry any accuracy other than about its temporal information;
Spatio-temporal relationships that do not include time information, are not included in a path.
Risk / Benefit analysis
Benefits
Risks
Competencies demonstrated
Competency 1
In CP-409 (#409), CQ's have been defined for location competencies that are agnostic to any temporal aspects. These CQ's can be repeated here, with the addition of either "at time T" or "during the period [T1, T2]". The answers to the CQs are similar but will now take the temporal dimension into consideration.
Competency Question 1.1
What was the location of the photographing device when this picture was taken?
Result 1.1
Competency Question 1.2
Result 1.2
Solution suggestion
We suggest the use of semantic trajectories, e.g., Hu Y., e.a. (2013), to build the SpatioTemporalPoint.
Literature / References:
Hu, Y., Janowicz, K., Carral, D., Scheider, S., Kuhn, W., Berg-Cross, G., Hitzler, P., Dean, M., & Kolas, D. (2013). A Geo-ontology Design Pattern for Semantic Trajectories. In T. Tenbrink, J. G. Stell, A. Galton, & Z. Wood (Eds.), Lecture Notes in Computer Science (Vol. 8116, pp. 438–456). https://doi.org/10.1007/978-3-319-01790-7_24
Background
Physical resources can be located at different
Locationsat differentTimes, creating a demand for relating spatial information with time information. Indeed, having two distinct spatio-temporal pairs registered with an object, e.g.,<L1; T1>and<L2; T2>, implies that the object have been moved from the first location to the second, somewhere between timesT1andT2. Initiatives exist to support semantic trajectories, that is, a route that is composed of connections between points that can originate from different sources and be represented differently, but together make up the complete trajectory that is traversed by a subjectThis CP will cover both situations: First, to provide the capability to register an object at certain locations at certain moments; second, to reveal the underlying fact that the object has been moved. The first one simply ties one or more spatio-temporal pairs to an object, agnostic to the underlying movement; the second one follows up on the spatio-temporal pairs that the object is bound to and derives the geographical paths that the object was moved over in time, its so-called semantic trajectory.
Requirements
Requirement 1 - Spatio-temporal characteristics
This requirement exists in order to register a location of an object at a certain moment.
<L; T>.unknownwhilst providing the location information.Requirement 2 - Semantic trajectory
A semantic trajectory registers the spatial movements of an object over time, explicitly acknowledging the paths in between the spatial locations that the object has been moved over during a certain time interval. The path does not need to be the exact trajectory that has been taken, although such is not excluded as well.
Risk / Benefit analysis
Benefits
Risks
Competencies demonstrated
Competency 1
In CP-409 (#409), CQ's have been defined for location competencies that are agnostic to any temporal aspects. These CQ's can be repeated here, with the addition of either "at time T" or "during the period [T1, T2]". The answers to the CQs are similar but will now take the temporal dimension into consideration.
Competency Question 1.1
What was the location of the photographing device when this picture was taken?
Result 1.1
Competency Question 1.2
Result 1.2
Solution suggestion
We suggest the use of semantic trajectories, e.g., Hu Y., e.a. (2013), to build the SpatioTemporalPoint.
Literature / References: