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Michael Grupp edited this page Jun 5, 2020 · 31 revisions

Trajectories

Executables that load trajectories support different formats. You can specify the format you want to use with the mode switch (2nd argument), for example: evo_traj tum ... or evo_traj kitti .... This document provides information about these file formats.

Tip: if you don't know which format you should use for your SLAM algorithm, use the TUM format. It's simple, but can be converted to any other format later and doesn't require ROS.

bag - ROS bagfile

Note: requires a ROS installation

Currently, bagfiles with topics that contain geometry_msgs/PoseStamped, geometry_msgs/TransformStamped, geometry_msgs/PoseWithCovarianceStamped and nav_msgs/Odometry messages are supported. evo only reads the trajectory, thus covariance or twist aren't used.

New since v1.9: TF topics are now also supported. You can load the trajectory of a TF transform in the command line apps with specifier <topic>:<parent_frame>.<child_frame>. E.g. evo_traj bag my_data.bag /tf:map.base_link /tf:odom.base_link will load the trajectories of the transform chain "map to base_link" and "odom to base_link" from the topic /tf.

More infos:

or run: rosmsg show geometry_msgs/PoseStamped

euroc - EuRoC MAV dataset format

Every sequence of the EuRoC MAV dataset has .csv files with various ground truth information. For us, only the first columns with the ground truth's trajectory are important (timestamps, positions and orientations).

You can find these files in the sequence folder: <sequence>/mav0/state_groundtruth_estimate0/data.csv

This format only makes sense for these ground truth files because they have additional data (which we don't need). If you use the EuRoC dataset, you usually need to save the trajectory in another format like the TUM format (e.g. ORB-SLAM does it like that).

In euroc mode, evo's metrics require you to give the reference in the EuRoC format and the estimated trajectory in the TUM format.

More infos: http://projects.asl.ethz.ch/datasets/doku.php?id=kmavvisualinertialdatasets#the_euroc_mav_dataset

WARNING be careful with the EuRoC dataset coordinate frames (ground truth, IMU, camera...), because they have different axis conventions.

kitti - KITTI dataset pose format

This is actually not a real trajectory format because it has no timestamps - it only contains the poses in a text file. This means that you have to be careful when you want to compare two files in this format with a metric because the number of poses must be exactly the same.

Every row of the file contains the first 3 rows of a 4x4 homogeneous pose matrix (SE(3) matrix) flattened into one line, with each value separated by a space. For example, this pose matrix:

a b c d
e f g h
i j k l
0 0 0 1

will appear in the file as the row:

a b c d e f g h i j k l

More infos: http://www.cvlibs.net/datasets/kitti/eval_odometry.php

tum - TUM RGB-D dataset trajectory format

Every row has 8 entries containing timestamp (in seconds), position and orientation (as quaternion) with each value separated by a space:

timestamp x y z q_x q_y q_z q_w

More infos: https://vision.in.tum.de/data/datasets/rgbd-dataset/file_formats

Saving / Exporting to other formats

In general, you can export trajectories to other formats with evo_traj using the --save_as_<other_format> options.

The following combinations are possible:

--save_as_bag --save_as_kitti --save_as_tum
bag yes yes yes
euroc yes yes yes
kitti no (no timestamps) yes no (no timestamps)*
tum yes yes yes

*... but you can use this script together with the timestamp files of the KITTI dataset

exported ROS bag files will contain geometry_msgs/PoseStamped messages

Example:

# export a EuRoC groundtruth file to a TUM trajectory
evo_traj euroc data.csv --save_as_tum
# (will be saved as data.tum)

# export TUM trajectories to KITTI format
evo_traj tum traj_1.txt traj_2.txt traj_3.txt --save_as_kitti
# (will be saved as *.kitti)

# export TUM trajectories to ROS bagfile
evo_traj tum traj_1.txt traj_2.txt traj_3.txt --save_as_bag
# (will be saved as <timestamp>.bag with topics traj_1, traj_2 and traj_3)

# and so on...

There is no --save_as_euroc option because the EuRoC format only makes sense for the ground truth of the EuRoC dataset.

Note: Prior to version 1.0.5, there was a bug with the quaternions if TUM files were exported. Make sure your version is at least v1.0.5 with evo pkg --version or upgrade.

Result zip files for evo_res

These files generated by a metric with the --save_results option contain the data that is needed to compare different results with evo_res. They are just .zip files that contain a few .json files and .npz files for storing larger numpy arrays.

If you want, you can also store a backup of the trajectories that were used to generate the result in the .zip file. To do this automatically whenever you use --save_results, change the settings:

evo_config set save_traj_in_zip true

Note that this will increase the size of the files.

Usage

Customization

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