ST_deviation
更新时间：
复制 MD 格式
Returns the spatial deviation between a processed trajectory and the original trajectory. A smaller return value indicates that the processed trajectory more closely approximates the original. Call this function after trajectory compression to evaluate quality loss.
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 the output of ST_compress. |
Example
The following query compresses a trajectory using a tolerance of 0.001 and then measures the deviation of the compressed trajectory from the original.
SELECT ST_deviation(traj, ST_compress(traj, 0.001)) FROM traj_test;Output:
st_deviation
---------------------
0.00919177345596219
(1 row)See also
ST_compress: Compress a trajectory object to reduce its size.
该文章对您有帮助吗？