How to Use Laser Data
I want to use laser data in my program(I want C++ code)
,
I can see ranges data of laser scanner with #rostopic echo /scan/ranges but how can i use it in my codes.
add a comment
Thanks Dear Stefan for your time... I want to read for example ranges[50], I do it by bellow code but it caused error: `Segmentation fault (core dumped)` "sensor_msgs:: LaserScan scan; std::cout<<scan.ranges[20]<<std::endl;" what's="" my="" problem?<="" p="">
1
You instantiate a empty LaserScan message and try to access element 50 of the ranges vector, which does not exist.
What i must to do Stefan to read for example ranges[20] ?? when i use "rostopic echo /scan/ranges" it print a lots of ranges, i think it was more than 200s...
1
Sorry to be blunt, but you will have to do some basic studying of C++ and the C++ ROS API. The code piece you posted just creates a empty message and tries to access (the non-existing) 20th or 50th range of it. You have to actually subscribe to the topic and use a callback to get the data coming in on a topic. See http://wiki.ros.org/ROS/Tutorials/WritingPublisherSubscriber(c%2B%2B) to get a basic understanding of how subscribing to topics works.
Thanks Dear Stefan, I had not read that tutorial... I'm was Stupid... sorry for my silly question. ;-)
