ST_deviation

Returns the deviation between a processed trajectory object and the original trajectory object. Use this function to measure how much a trajectory changes after operations such as compression.

The return value is a float8 scalar.

Syntax

float8 ST_deviation(trajectory traj, trajectory after_oper_traj);

Parameters

Parameter	Description
`traj`	The original trajectory object.
`after_oper_traj`	The processed trajectory object, such as a compressed trajectory.

Example

The following example computes the deviation introduced by compressing a trajectory with a tolerance of 0.001:

SELECT st_deviation(traj, st_compress(traj, 0.001)) FROM traj_test;
    st_deviation
---------------------
 0.00919177345596219
(1 row)

What's next

ST_compress: Compress a trajectory object with a specified tolerance.