Instructions for Use
With the rapid development of navigation positioning, mobile internet and other technologies, trajectory big data has become a classic type of spatiotemporal big data.
However, due to communication anomalies, positioning errors, and other reasons, it is difficult to ensure that the trajectory point data fully matches the road network. Map matching is the process of associating a series of ordered trajectory location points with the actual road network, which can be seen as a data preprocessing task in trajectory data processing, serving the subsequent calculation and analysis of trajectory lines.
The purple point set in the following figure represents the trajectory point data, while the solid blue line represents the line data after matching the trajectory points with the road.
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Map matching divides trajectory points into identification fields, sorts and segments trajectories based on time fields, and finds the most likely road section that each trajectory passes through, with the aim of restoring the true path based on trajectory points. If map matching is not performed, the action trajectory may deviate from the road network (such as locating to roadside buildings, ponds, etc.).
You can use processing automation to build a complete map matching process (recommended). The following figure shows the model for building map matching:
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be careful:
*Map matching requires the use of network data models and best path analysis methods in the SuperMap iObjects Java component.
*The result returns the Trajectory Line Dataset (FeatureRDD). In the result data, each trajectory line will generate a start time field and an end time field to record the start and end time of the current trajectory.
Parameter Description
| Parameter Name | Default Value | Parameter Definition | Parameter Type |
|---|---|---|---|
| Trajectory Point Dataset | Trajectory Point Dataset | FeatureRDD | |
| Point identification field | Point identification field, where points with the same identification are grouped together, for example, phone number | String | |
| Field used to identify element time | Field used to identify element time. If the time field is not set, the default time field will be found from the element dataset. If there is no default time field, an exception will be thrown | String | |
| Trajectory segmentation object (Optional) |
Trajectory segmentation object can be constructed using the [Create Trajectory Segmentation Object] operator | TrackSplitter | |
| The best path analysis parameters | The best path analysis parameters can be created through the [Build SSC Path Analysis Parameters] operator and the [Build Path Analysis Parameters] operator | PathAnalystSettingInfo | |
| Trajectory point error value (Optional) |
30.0 | Trajectory point error value, such as GPS error value, in meters. If the distance from the trajectory point to the nearest road exceeds the error value, it is considered illegal. Therefore, setting a reasonable error value has a direct impact on the results of map matching. If the obtained trajectory points have high accuracy, setting a smaller value can effectively improve performance, such as 15 meters. The default value is 30 meters | Double |
| Maximum speed limit (Optional) |
150.0 | Maximum speed limit, in kilometers per hour. When the speed value calculated for two adjacent points is greater than the specified limit speed, it is considered that these two points are unreachable, that is, there is no effective road connection. The default value is 150 km/h | Double |