ROS topics empty

[isokar]

Hi,
I'm trying to use ORB_SLAM2 on Jetson Nano.
I managed to install it and to launch the ROS example. here is what I got:

`
isokar@ROSMain:~$ roslaunch /home/isokar/ORB_SLAM2_CUDA/Examples/ROS/ORB_SLAM2_CUDA/launch/ros_mono.launch
... logging to /home/isokar/.ros/log/0bbe5eda-9c6a-11ea-ae95-4ae0e495c825/roslaunch-ROSMain-22881.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://ROSMain:39619/

SUMMARY

PARAMETERS

• /rosdistro: melodic
• /rosversion: 1.14.3

NODES
/
ORB_SLAM2_CUDA (ORB_SLAM2_CUDA/Mono)

ROS_MASTER_URI=http://localhost:11311

process[ORB_SLAM2_CUDA-1]: started with pid [22898]

ORB-SLAM2 Copyright (C) 2014-2016 Raul Mur-Artal, University of Zaragoza.
This program comes with ABSOLUTELY NO WARRANTY;
This is free software, and you are welcome to redistribute it
under certain conditions. See LICENSE.txt.

Input sensor was set to: Monocular

Loading ORB Vocabulary. This could take a while...
Vocabulary loaded!

Camera Parameters:

• fx: 527.546
• fy: 528.822
• cx: 360.76
• cy: 225.48
• k1: 0.262383
• k2: -0.953104
• k3: 1.16331
• p1: -0.005358
• p2: 0.002628
• fps: 10
• color order: RGB (ignored if grayscale)

ORB Extractor Parameters:

• Number of Features: 2000
• Scale Levels: 8
• Scale Factor: 1.2
• Initial Fast Threshold: 20
• Minimum Fast Threshold: 7
  Image reading time = 7.0158e-05s
  Tracking time = 1.26621s, frequency = 0.78976Hz
  All cost time = 1.26628s, frequency = 0.789716Hz
  Avg. time = 1.26628s, frequency = 0.789716Hz

Image reading time = 8.646e-06s
Tracking time = 0.143114s, frequency = 6.98744Hz
All cost time = 0.143123s, frequency = 6.98702Hz
Avg. time = 0.7047s, frequency = 1.41904Hz

Image reading time = 7.084e-06s
Tracking time = 0.0886575s, frequency = 11.2794Hz
All cost time = 0.0886646s, frequency = 11.2785Hz
Avg. time = 0.499355s, frequency = 2.00258Hz

Image reading time = 8.229e-06s
Tracking time = 0.106942s, frequency = 9.35086Hz
All cost time = 0.10695s, frequency = 9.35014Hz
Avg. time = 0.401254s, frequency = 2.49219Hz

Image reading time = 8.334e-06s
Tracking time = 0.094746s, frequency = 10.5545Hz
All cost time = 0.0947543s, frequency = 10.5536Hz
Avg. time = 0.339954s, frequency = 2.94158Hz

^CImage reading time = 1.1771e-05s
Tracking time = 0.0983063s, frequency = 10.1723Hz
All cost time = 0.098318s, frequency = 10.1711Hz
Avg. time = 0.299681s, frequency = 3.33688Hz

[ORB_SLAM2_CUDA-1] killing on exit

Saving keyframe trajectory to /home/ubuntu/ORB_SLAM2_CUDA/test_results/Mono_KeyFrameTrajectory.txt ...

trajectory saved!
shutting down processing monitor...
... shutting down processing monitor complete
done
`

so it seems to works fine and detects images.
but when opening RVIZ(or doing rostopic echo), the topics are created but empty.
what am I doing wrong?

[thien94]

Hi @isokar , so sorry for the late reply.
Is the option to publish ROS topics enabled? If yes, can you verify the individual topic in this part of the code.

[isokar]

Hi,
I Just found out part of the reason of my problem.
by adding some logs to ros_mono I found out that "Tcw" variable is empty, which cause to stop.
Now I have to find out why it's empty. if any idea...

I calibrated the camera just to be sure but with no changes.

[nestormh]

Hello,

I was having the same issue, with no messages after the line https://github.com/thien94/ORB_SLAM2_CUDA/blob/master/Examples/ROS/ORB_SLAM2_CUDA/src/ros_mono.cc#L138.

I finally was able to start sending messages when I adjusted the configuration file so the threshold was lower, with the following parameters:

• ORBextractor.iniThFAST
• ORBextractor.minThFAST

and especially after increasing ORBextractor.nFeatures.

To begin, you can try to be as permissive as possible, just to check it works (by setting a large number of features and a low threshold. This will lead to a low frame rate and precision, but at least you can check it is working properly)

For instance, with this configuration:

# ORB Extractor: Number of features per image
ORBextractor.nFeatures: 10000

# ORB Extractor: Scale factor between levels in the scale pyramid       
ORBextractor.scaleFactor: 1.2

# ORB Extractor: Number of levels in the scale pyramid  
ORBextractor.nLevels: 8

# ORB Extractor: Fast threshold
# Image is divided in a grid. At each cell FAST are extracted imposing a minimum response.
# Firstly we impose iniThFAST. If no corners are detected we impose a lower value minThFAST
# You can lower these values if your images have low contrast                   
ORBextractor.iniThFAST: 20
ORBextractor.minThFAST: 7

I am being able to get a /posestamped topic at ~11Hz. These parameters are not ideal, of course, since 10K features seem to be too much, but you can try these a parameters as a baseline to check it is at least working, and from there try to find the best parameters for your specific case.

It looks like it was having some issues getting a match between frames. Try not to move the camera at the beginning for several seconds. Then you will start seeing messages in the /posestamped topic.

In my case, I am still losing many messages at certain frames but I guess it is a matter of refining the configuration (I still have not calibrated my camera, so this is to be expected). But what matters is that the problem is solved if you find a configuration in which you can ensure a match between frames given your current light conditions, image quality, etc.

I hope it helps.