Slide 12 of 29
There is no explicit relationship between snapshots or between corresponding points (pixels, objects) in the layer. Querying has to be by restoring archive copies or rolling back transactions (if based on a db). If each snapshot is multi-themed (layered) , there are no facilties to relate successive snapshots of the same theme.
Stores states, not changes (events).
Hard to say what facilities are provided in any of these t-GIS types since all of them are research prototypes, each with variants.
Irregular intervals between snapshots. If each snapshot is a raster image, they may not register (e.g. from different satellite swaths) and each one may not cover the entire area.
Diagram from May Yuan’s paper on NCGIA website.
