Example for converting an ASCII trajectory containing LLA positions into an Exwayz trajectory, by projecting positions using (auto-computed) UTM projection. The position of the useful fields are specified in the --ascii-cfg configuration file.
exwayz_traj_conversion **--no-gui --src-fmt** ascii **--src <path/to/ascii/trajectory> --dst-proj UTM --ascii-cfg <path/to/ascii/config/file>**
Example for converting a file containing NMEA frames into an Exwayz trajectory, by projecting positions using (auto-computed) UTM projection and writes it to traj_conversion.ply
exwayz_traj_conversion **--no-gui --src-fmt** nmea **--src <path/to/nmea/log> --dst-proj UTM -o traj_conversion.ply**
Trajectory in Exwayz format (ply) containing X, Y, Z coordinates and timestamps
| Name | Command line prefix | Default value | Definition |
|---|---|---|---|
| Disable GUI | --no-gui |
Disable the GUI application. This option must be set for using the software as a commandline executable | |
| Input format | --src-fmt [arg] |
Required | Format of the input data. Possible values are: ascii, nmea or ply. |
| Output format | --dst-fmt [arg] |
ply |
Format of the output trajectory. Possible values are: ascii or ply. |
| Input file | --src [arg] |
Required | Input data file. |
| Output trajectory name | -o [arg] |
./traj_gps.ply |
Define a output converted trajectory |
| ASCII configuration file | --ascii-cfg |
- | ASCII configuration file that contains the parsing information of the input ASCII file. Check section Configure your ASCII configuration file |
| Source projection | --src-proj |
- | Source projection CRS of the input trajectory. |
| Destination projection | --dst-proj |
- | Destination projection CRS for projection the LLA of the input trajectory. If set to UTM, CRS will be computed automatically to based on the computed UTM zone corresponding to the first trajectory LLA. |
| Help | -h or --help |
- | Prints help message |
--src-proj and --dst-proj program arguments expect input EPSG string (e.g. EPSG:4326 for WGS 84). This string defines uniquely a Coordinate Reference System (CRS). You can find all CRS and their associated EPSG string code in this website: https://epsg.io/
Here is a list of the most commonly used CRS:
| CRS | EPSG string | Coordinates |
|---|---|---|
| WGS 84 | EPSG:4326 | lat, lon, altitude |
| WGS 84 / UTM Zone * N | EPSG:326* (* is the 2 digits number of the zone) | ENU |
| WGS 84 / UTM Zone * S | EPSG:327* (* is the 2 digits number of the zone) | ENU |
| Lambert 93 | EPSG:2154 | ENU |
The table below sums up the program behaviors depending on whether --src-proj and/or --dst-proj are provided as console argument.
--src-proj |
--dst-proj |
Program behaviour |
|---|---|---|
| - | - | No geographic projection is performed. |
| EPSG string | - | The input trajectory is projected from src-proj to WGS84 (EPSG:4326). |
| - | EPSG string | The input trajectory is projected from WGS84 (EPSG:4326) to dst-proj . |
| - | UTM | UTM zone is automatically computed from the input trajectory data, then input trajectory is projected from WGS84 to the computed UTM zone. |
| EPSG string | EPSG string | The input trajectory is projected from src-proj to dst-proj. |
--ascii-config console argument (CLI usage) or ASCII config (GUI usage) is used to provide to the executable the parsing rules for extracting LLA and other useful information such as timestamps in the input ASCII file.
General structure:
# YAML file
<general parameters>
<position parsing parameters>
<time parsing parameters>
<rotation parsing parameters> [--> optional]
<filtering parameters> [--> optional]
Basic example:
delimiters: [","] # Delimiter(s) used in the ASCII file.
header_length: 0 # Number of lines composing the header.
latitude_column: 13 # Column index, starting from 1, on which are located the latitude values
longitude_column: 12 # Column index, starting from 1, on which are located the longitudesvalues
altitude_column: 14 # Column index, starting from 1, on which are located the altitudes values
time_column: 2 # Column index, starting from 1, on which are located the timestamps
time_scale: 1e-3 # Scaling factor to convert the times in seconds. For instance, if times are expressed in millisecons, the time scale should be 1e-3