kam3k / laser_line_extraction Goto Github PK

Could you please add to the repo the laser scan messages from which you created that example gif? If you do not have those messages, then can you please add any laser scan message that produces a nice set of walls given the default parameters? I am playing with your code, and having known working laser scan messages would greatly help debug issues that I am encountering. Thanks!

Hi!

I'm using your algorithm to detect lines in a factory environment for a graduation project on robotics. The code works very nice, so my compliments for that! Nevertheless, one problem I have is that I cannot seem to detect a line when only one line is present in the laserscan data. Can you advise me on which settings to change or where to adapt the code?

Best,
Sebas

Hi, when I have an angular increment higher than 0.01 rad, the algorithm publishes the line markers in a circle at the max range of the scan message (I have a resolution of 0.0022 rad from my scanner, with a 270 degrees field of view). This problem can be easily reproduced both in simulation and on actual laser data. I tried all parameters, but apart from getting one small segment converging into line, nothing works. Any idea what I can try?

Hi!

I put 2 obstacles (Gazbo box obstacles in the same dimension), one of them in front side of the robot (and its ), the other in the rear side.

Unfortunately the rear one has not been recognized and in my case I need the rear side lines.

Is there any method to deal with it?

Hello,

Thank you for sharing the example. I am newbie on ROS. I want to try this algorithm on my project. When i launch "example.launch" there is no error but want to see lines on Rviz. I will be glad how to implement it. I searched files but nothing found about Rviz package.

My system:
Hardware: Nvdia Jetson Nano
OS: Ubuntu 18.4
ROS: Melodic version
Lidar: Slamtec Rplidar S1

what exactly the function distToPoint from the Line class does?

• calculate the distance of a point to is orthogonal projection on the line segment?
• calculate the distance of a point to the start of the line segment?

thanks in advance

Hello!
I managed to run the package and visualize the lines from /marker topic through rviz. But when I am trying to access the topic /line_segments to get the list of lines I get the following error:

ERROR: Cannot load message class for [laser_line_extraction/LineSegmentList]. Are your messages built?

The topic appears in the list of active topics with rostopic lists, but rqt_graph does not include it. When I try to see the published messages with rostopic echo I get the error above. I tried to clean the workspace with catkin_make clean and rebuild it with catkin_make, then source again the environment but still, I get the same error. I think I am missing something here. Can you please provide any hint?

Thanks in advance!

Hi,
I want to use your package to create a wall following algorithm where instead of checking directly the distance to the wall through the laserscanner points, I want to just compute the distance to the line. I see that the output of the line_segment topic is the polar coordinates. which angle of the robot does the r value given corresponds to ? Thanks in advance.

Hi!

I am a Msc student in China, and trying to use a UAV, assembled with a 2D-lidar, to flying in a tunnel. Lidar is using to detect the surface of the tunnel ,which can be treated as a line in 2D-lidar data.
By searching, I found your code in the github and it seems works very well. So I download and catkin_make it.
But what confuse me is, I see no segments output data from the /line_segments. I play around the parameters but nothing change, then I trying to use printf to print the data and fail again. I am new to C++ ROS coding， so can you give some advices on how to deal with this problem or usually how you debug the code?

I leave my parameter below, and my rosbag link. By the way, I am using the /scan_filtered topic.

Best,
Lin

bag file:
https://github.com/eleboss/UAV/blob/master/2018-01-22-15-28-43.bag

tunnel:
https://github.com/eleboss/UAV/blob/master/Screenshot%20from%202018-01-22%2015-10-25.png

Hello. I just saw that you added the max_range parameter in the example.launch (it was mentioned in the readme but not included in the file). I installed the package yesterday, so I tried to add the parameter in the launch file but it didn't work. Did you make any changes in the other files to make the max_range work? should I install the package from the beginning?

Thanks in advance!

Do you plan to migrate the package to ROS2?

Hello!
I'm newbie in ROS, and trying to save lines coordinates, (published in map fixed frame), and export to a dxf file format. But the result got wrong. It looks like lines are in laser frame, so they are "rotating".

I checked frame_id via rostopic echo /line_markers or /line_segments and it says "map" as changed in launch file.

Can you give some tip on how to get the line coordinates correctly?

I can save point cloud coordinates and create a dxf file with this points (add_point), and then draw lines over it; but if I could use line coordinates, I could create lines directly (add_line) and it would give a lot less data (since i would have just 2 points - start|end, and not all the wall points)

The first and second images shows the result using line markers and line coordinates start-end points.
Last image shows the result using point cloud coordinates, transformed to frame "map".

Thank you!

I'm using the package with the above parameters to get line segments from laser data. I want to extract my lines as closer to the real length as possible, but the parameters I use don't correspond to the segment I get. I was playing with the parameters for a week and I found out that, maybe because of some reflections, some of the measurements return "nan" instead of a range number. How does the algorithm deals with this "nan" data? Is this why the segment in the image is shorter than the whole length of the measurements? Or maybe there is a better combination of parameters that solves the problem? Any help will be appreciated. Thanks in advance!

ERROR: cannot launch node of type [laser_line_extraction/line_extraction_node]: can't locate node [line_extraction_node] in package [laser_line_extraction]

Thanks for sharing the useful repository, I just wonder will work for 3D lines in case of 3D lidar?

Appreciate any response.