Spatiotemporal GIS: Incorporating Time Group 7 Nathan Hunstad, Kyle Martin Csci 5980

Spatiotemporal GIS: Definitions Standard GIS: Spatial characteristics only – Implicit time is usually “now” Spatiotemporal GIS: Adds concept of time – What happened when (and why)? – Examples: Pandemic response, traffic modeling

Spatiotemporal GIS: Definitions Spatiotemporal GIS requires explicit definitions of terms like “event”, “action”, and “process” – Several classification systems Transaction time versus Valid Time – Transaction time: time of data entry – Valid time: time data applies – Bitemporal: uses both times

Spatiotemporal GIS: Definitions Timeline definition – Can be continuous, rational or discrete (ticks of a clock) – Consists of both discrete instants and intervals Data structures – Standard data structures are ill-suited for temporal data – Alternatives include overlapping B-trees, multiversion B-trees, and historical R-trees

Spatiotemporal GIS: Querying Spatiotemporal Query Languages – An extension of standard languages like SQL – Allow for querying spatiotemporal concepts directly without complicated queries

Spatiotemporal GIS: Querying Language Applications – Applications used with moving objects – Applications dealing with discrete changes – Applications dealing with changing motion and shape

Spatiotemporal GIS: Continuous Data Continuous Queries update as data changes Types of queries – Continuous range queries – Continuous nearest neighbor – Continuous reverse nearest-neighbor

Spatiotemporal GIS: Continuous Data Modeling queries – Static queries over moving objects – Moving queries over static objects – Moving queries over moving objects

Spatiotemporal GIS: Continuous Data Applications – Traffic Monitoring – Traffic Pattern Detection – Location-Based E-commerce – Digital Battlefield – Road-Trip Assistance

Spatiotemporal GIS: Moving Object Languages MOST: Moving Object Spatio-Temporal data model – Problem: point-based data types need constant updating – Solution: Use vectors and maximum distance threshold

Spatiotemporal GIS: Moving Object Languages Query Language: FTL – Similar to first-order logic – As time progresses, results returned can be changed

Spatiotemporal GIS: Future Applications Many systems still use simple timestamping – Can't represent issues like dispersion and movement Challenges to more robust systems – Disagreements over ontology – Representing complex processes – Causal querying – Better statistical analysis and testing

Spatiotemporal GIS: Similarities/Differences Chapter 10Encyclopedis GIS Attribute Timestamping (x and y position) Vector representation Stringent definitions of “Actions” and “Events” Both “Discrete” and “Continuous” timelines “Discrete” and “Abstract” timelines