Don´t understand ROS::nodehandler [closed]

asked 2016-08-15 10:00:34 -0600

I have the following code.

double globalResizingFactor; ros::init(argc, argv, "image_listener"); ros::NodeHandle nh; ...

if (!nh.getParam("resizing_factor", globalResizingFactor)) { ROS_ERROR (" .... "); ros::shutdown(); }

This code compiles with no problems, but it is a transition from a old ROS distribution to a more recente one, this is, Fuerte to Hydro, both are very diferent, a made a huge problem to be solved, the fact is that I was able to change e few things and compile.

When Runing It stops here, at this if, since the globalResizingFactor isn´t got, it fails. Please some help understanding what´s hapening in this code.

Rodrigo

Closed for the following reason duplicate question by Rodrigo Lourenço
close date 2016-08-23 06:17:51.689651

answered 2016-08-15 15:32:37 -0600

ghkraju
80 ●9 ●10 ●15

nh.getParam("variable", variable in class) will get the values from your launch file or you have to pass the value when you launch your node something like rosrun [package_name] [node_name] [variable="resizing_factor"] (don't use [] that is just for your understanding)

In your case, probably the values are not getting passed while launching the node so it falls in ROS_ERROR. Please try the above method or use a launch file.

For launch file, follow this link: http://wiki.ros.org/roslaunch/XML Refer 5.1 and 5.3 I hope this will help to solve your problem.