STS_TrajectoryDistance function

The STS_TrajectoryDistance function returns the shortest distance between the specified point and the trajectory of the specified moving object in the specified time range.

Syntax

STS_TrajectoryDistance(
                       ts             TimeSeries, 
                       begin_time     DATETIME YEAR TO FRACTION(5), 
                       end_time       DATETIME YEAR TO FRACTION(5), 
                       point          ST_Point,
                       max_distance   FLOAT)
returns FLOAT

STS_TrajectoryDistance(
                       ts             TimeSeries, 
                       begin_time     DATETIME YEAR TO FRACTION(5), 
                       end_time       DATETIME YEAR TO FRACTION(5), 
                       point          ST_Point,
                       max_distance   FLOAT,
                       uom            VARCHAR(128))
returns FLOAT

ts: The name of the time series.
begin_time: The start of the time range. Can be NULL to indicate the first element in the time series.
end_time: The end of the time range. Can be NULL to indicate the last element in the time series.
point: An ST_Point object.
max_distance: The distance from the point that defines the region of interest. The unit of measure is specified by the uom parameter.
uom (Optional): The unit of measure for the radius parameter. If unitOfMeasure is not specified, then it is meter for a geographic coordinate systems, and, it is the linear unit of measure for projected coordinate systems. If the projected coordinate system does not have a linear unit of measure specified, it is meter. Must be the name of a linear unit of measure from the unit_name column of the st_units_of_measure table.

Usage

Run the STS_TrajectoryDistance function to find how close an object came to a specific point during a time range.

The following illustration shows a trajectory near the point (-78.7043 42.9197). A line connects the closest part of the trajectory to the point.

The image shows a trajectory and a point (-78.7043 42.9197) and the closest point on the trajectory to the point (-78.7043 42.9197). — Figure 1: The shortest distance between a trajectory and a point

Returns

A FLOAT value = The distance in the specified unit of measure.

NULL = Nothing found.

Example

The following query returns the shortest distance of vehicle 1002 from the specified location between the times of 2015-06-14 12:30:00 and 2015-06-14 13:00:00:

SELECT modid, round(STS_TrajectoryDistance(ts_track, 
         '2015-06-14 12:30:00', '2015-06-14 13:00:00',
         '4326 point(-78.7043 43.9197)', 10.0, 'meter'), 1) 
         FROM t_vehicle 
         WHERE modid = 1002;

modid                                     (expression)
1002                                              4.3

1 row(s) retrieved.