event_array_tools

This repository holds ROS/ROS2 tools for displaying and converting event_array_msgs under ROS and ROS2. These messages are produced by the metavision_ros_driver.

Supported platforms

Currently tested on Ubuntu 20.04 under ROS Noetic and ROS2 Galactic.

How to build

Create a workspace (event_array_tools_ws), clone this repo, and use vcs to pull in the remaining dependencies:

pkg=event_array_tools
mkdir -p ~/${pkg}_ws/src
cd ~/${pkg}_ws
git clone https://github.com/berndpfrommer/${pkg}.git src/${pkg}
cd src
vcs import < ${pkg}/${pkg}.repos
cd ..

configure and build on ROS1:

catkin config -DCMAKE_BUILD_TYPE=RelWithDebInfo  # (optionally add -DCMAKE_EXPORT_COMPILE_COMMANDS=1)
catkin build

configure and build on ROS2:

cd ~/${pkg}_ws
colcon build --symlink-install --cmake-args -DCMAKE_BUILD_TYPE=RelWithDebInfo  # (optionally add -DCMAKE_EXPORT_COMPILE_COMMANDS=1)

Republish conversion nodelet

The republish node converts event_array_msgs to legacy formats like dvs, prophesee, and decoded ("mono") event_array messages. Note that this nodelet will be consuming a significant amount of CPU resources and should not be run unnecessarily while recording data. The following command will start a conversion nodelet to republish events from /event_camera/events to /event_camera/republished_events and /event_camera/republished_triggers (similar syntax under ROS2, see launch file for remapping):

roslaunch event_array_tools republish_nodelet.launch camera:=event_camera message_type:=event_array

Tools

All tools are provided in ROS and ROS2 (syntax below is for ROS):

rosrun event_array_tools echo [-b <bag>] <topic>: displays messages in event_array_msgs format, optionally from a bag file. Example output:

-------------------------------
res:  640  height:  480 enc: evt3
header stamp: 1664227781775114816
time base:        0
seqno:   129213
---
6851488000 edge: 1  id:  6
6851510000  390  223 1
6851520000   33  326 0
...

rosrun event_array_tools perf <topic>: Sample output:
```
msgs:   219.48/s drp:  0 del: 13.72ms drft: 0.0033s ev:   0.0823 M/s %ON:  46 tr:  1758.38 1/s %UP:  50
msgs:   249.01/s drp:  0 del:  4.35ms drft: 0.0027s ev:   0.8497 M/s %ON:  52 tr:  1999.56 1/s %UP:  49
```
The meaning of the fields is as follows:
- msgs message rate per seconds
- drp number of drops per second (skip in sequence numbers)
- del delay: average time difference between message header stamp and arrival time. This includes the delay due to the driver aggregating messages.
- drft accumulated (from start of "perf") drift between message header stamp and sensor-provided time.
- ev event rate in millions/sec
- %ON ratio of ON events to total (ON + OFF) events
- tr rate of trigger messages
- %UP ratio of UP trigger edges to total (UP + DOWN)
rosrun event_array_tools sync_test <cam_0_event_topic> <cam_1_event_topic> The output gives the average sensor time difference and how many samples where counted:
```
avg sensor diff:  0.00846s, count:   360
avg sensor diff:  0.00377s, count:   466
...
```
rosrun event_array_tools bag_to_raw -t <topic> -b <bag_name> -o <outout_raw_file> -c <camera_type> Converts bags with evt3 event_array_msgs to raw file. The camera_type argument is necessary to produce a valid header for the raw file.
rosrun event_array_tools raw_to_bag -t <topic> -b <bag_file> -i <input_raw_file> -w <sensor_width> -h <sensor_height> -B <buffer_size> Converts raw file into bag with evt3 event_array_msgs. The buffer size determines the size and number of ROS messages in the bag.
rosrun event_array_tools movie_maker -f <fps> -b <bag_name> -t <topic>: produces sequence of frame images.
rosrun event_array_tools legacy_to_bag -t <topic> -b <input_bag_file> -o <output_bag_file> ROS1 only: Converts bags with DVS or Prophesee messages to evt3 event_array_msgs.

License

This software is issued under the Apache License Version 2.0.

berndpfrommer/event_array_tools