对一条轨迹重采样。
语法
trajectory ST_Resample(trajectory traj, config);参数
参数名称 | 描述 |
traj | 被重采样的轨迹对象。 |
config | 重采样轨迹的规则。格式 |
目前包含以下可选规则，每次调用此函数时，仅可选择一个规则：
规则名称 | 参数类型 | 说明 |
add_point.distance_lesser | 浮点数 | 在每条轨迹线上均匀添加点，使每一段之间的距离均小于参数。 |
add_point.period_lesser | 可以转化为Interval类型的字符串 | 在每条轨迹线上均匀添加点，使每一段的时长均小于参数。 |
drop_point.distance_lesser | 浮点数 | 如果相邻多段轨迹线段上所有的点到起点的长度，均小于此参数给定的空间长度时，将其合并（仅保留起点和终点）。 |
drop_point.period_lesser | 可以转化为Interval类型的字符串 | 当相邻多段轨迹线段的时间长度之和小于给定的时间长度时，将其合并（仅保留起点和终点）。 |
描述
根据提前设定的规则对轨迹对象重采样，返回重采样后的轨迹。
示例
With traj As
(
select '{"trajectory":{"version":1,"type":"STPOINT","leafcount":5,"start_time":"2000-01-01 00:00:00","end_time":"2000-01-05 00:00:00","spatial":"LINESTRING(1 1,10 10,11 11,13 13,15 15)","timeline":["2000-01-01 00:00:00","2000-01-02 00:00:00","2000-01-03 00:00:00","2000-01-04 00:00:00","2000-01-05 00:00:00"]}}'::trajectory a
)
SELECT ST_Resample(a, '{"add_point.distance_lesser":3}') from traj;
st_resample
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
{"trajectory":{"version":1,"type":"STPOINT","leafcount":9,"start_time":"2000-01-01 00:00:00","end_time":"2000-01-05 00:00:00","spatial":"LINESTRING(1 1,2.8 2.8,4.6 4.6,6.4 6.4,8.2 8.2,10 10,11 11,13 13,15 15)","timeline":["2000-01-01 00:00:00","2000-01-01 04:48:00","2000-01-01 09:36:00","2000-01-01 14:24:00","2000-01-01 19:12:00","2000-01-02 00:00:00","2000-01-03 00:00:00","2000-01-04 00:00:00","2000-01-05 00:00:00"]}}
(1 row)
With traj As
(
select '{"trajectory":{"version":1,"type":"STPOINT","leafcount":5,"start_time":"2000-01-01 00:00:00","end_time":"2000-01-05 00:00:00","spatial":"LINESTRING(1 1,10 10,11 11,13 13,15 15)","timeline":["2000-01-01 00:00:00","2000-01-02 00:00:00","2000-01-03 00:00:00","2000-01-04 00:00:00","2000-01-05 00:00:00"]}}'::trajectory a
)
SELECT ST_Resample(a, '{"add_point.period_lesser":"0.5 day"}') from traj;
st_resample
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
{"trajectory":{"version":1,"type":"STPOINT","leafcount":9,"start_time":"2000-01-01 00:00:00","end_time":"2000-01-05 00:00:00","spatial":"LINESTRING(1 1,5.5 5.5,10 10,10.5 10.5,11 11,12 12,13 13,14 14,15 15)","timeline":["2000-01-01 00:00:00","2000-01-01 12:00:00","2000-01-02 00:00:00","2000-01-02 12:00:00","2000-01-03 00:00:00","2000-01-03 12:00:00","2000-01-04 00:00:00","2000-01-04 12:00:00","2000-01-05 00:00:00"]}}
(1 row)
With traj As
(
select '{"trajectory":{"version":1,"type":"STPOINT","leafcount":5,"start_time":"2000-01-01 00:00:00","end_time":"2000-01-05 00:00:00","spatial":"LINESTRING(1 1,10 10,11 11,13 13,15 15)","timeline":["2000-01-01 00:00:00","2000-01-02 00:00:00","2000-01-03 00:00:00","2000-01-04 00:00:00","2000-01-05 00:00:00"]}}'::trajectory a
)
SELECT ST_Resample(a, '{"drop_point.distance_lesser":3}') from traj;
st_resample
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
{"trajectory":{"version":1,"type":"STPOINT","leafcount":4,"start_time":"2000-01-01 00:00:00","end_time":"2000-01-05 00:00:00","spatial":"LINESTRING(1 1,10 10,13 13,15 15)","timeline":["2000-01-01 00:00:00","2000-01-02 00:00:00","2000-01-04 00:00:00","2000-01-05 00:00:00"]}}
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