Output
Output of fmm
The output of program fmm is a CSV file containing the following information based on user specification:
| Output fields | Type | Description |
|---|---|---|
| id | int | trajectory id |
| ogeom | string | original trajectory geometry |
| opath | list of int | edge matched to each point in trajectory |
| error | list of floats | distance from each point to its matched point |
| offset | list of floats | distance from the matched point to the start of the matched edge |
| length | list of floats | length of the matched edge for each point |
| spdist | list of floats | shortest path distances traversed between consecutive points |
| duration | list of floats | time difference (duration) between two consecutive GPS points |
| speed | list of floats | speed of the vehicle between two consecutive GPS points, calculated by spdist/duration |
| pgeom | string | a line connecting the matched points |
| cpath | list of int | the path traversed by the trajectory |
| tpath | list of int | edges traversed between consecutive points separated by ` |
| mgeom | string | the geometry of the cpath |
| ep | list of floats | emission probability in HMM for each matched point |
| tp | list of floats | transition probability in HMM for two consecutive matched points |
| all | - | all the above fields are exported |
By default, only cpath and mgeom are exported. The fields are illusrated by the image below.
Output of ubodt_gen
The output of program ubodt_gen is a CSV file or a Binary file, which is automatically detected from the file extension csv or bin. Binary file can be used to save space in case of a large road network.
The CSV file contains the following information:
| Columns | Type | Description |
|---|---|---|
| source | int | index of source node |
| target | int | index of target node |
| next_n | int | index of next node index visited from source to target |
| prev_n | int | index of the node visited before target |
| next_e | int | index of next edge visited from source to target |
| dist | float | shortest path distance from source to target |
Note
In UBODT, all the integers are stored as index of nodes or edges, the actual id of edge will be retrieved from the road network in map matching.