Space-Time Analytics of Tracks for the Understanding of Patterns of Life - Space-Time Integration in Geography and GIScience - page 374

Fig. 20.5 Examples of Geohash codes at Levels 4 and 5 and the alternate ordering schemes for
codes at even and odd levels. All codes at one level are of the same length. Codes in every 8 4or

4 8 unit are only differentiated by their last digits

Both chronological time and Geohash space provide structures in which space-
time elements of stops, moves, and tracks can be referenced to develop analytical
methods and distill higher level information from primitive observations. Below are
methods of space-time analytics based on the elements of tracks, stops, and moves
and associated time-oriented and space-oriented structures to discern patterns of life
with a case study to illustrate the procedures and potential findings.

20.5 Space-Time Analytics of Tracks to Elicit Patterns of Life

Here, patterns of life are space-time summaries of movements and from the sum-
maries to project activities. Since trajectories and paths cannot be directly derived
from location observations, additional assumptions, information and modeling
projections are required to determine the most likely trajectories and paths taken by
individuals. Methods to construct space-time summaries of movements are based
on stops, moves, and tracks from observed or recorded locations. To facilitate the
discussion, we use GPS observations for several individuals in Oklahoma, USA to
step through Space-Time Analytics procedures.

20.5.1 Stop Analysis

Location-aware devices record GPS points at regular intervals. Unless the devices
are equipped with a motion sensor, GPS location data files consist of streams of