How to set arg to a node from launch file?

asked 2012-10-16 05:06:35 -0600

aldo85ita
252 ●17 ●18 ●31

Hi everybody, I can't set the args of my gscam node by launch file (this node is different from the original,because I modified it). This is the most important piece of source of my modified gscam node:

int main(int argc, char** argv) {
    if (argc != 2)
     {
        ROS_WARN("WARNING: you should specify camera info properties!");
     }else{
         ROS_INFO("INFO: you have set camera properties file: %s\n",argv[1]);
         camera_info_file=g_string_new(argv[1]);
     }

This is a piece of my launch file:

<node pkg="gscam" type="gscam"
      name="gscam"
      cwd="node"
args="/home/aldo/Projects/4thRC/BergamoComponents/services_caller/camera_parameters_to_set.txt">
  <env name="GSCAM_CONFIG"
       value="multifilesrc location=&quot;/home/aldo/Documents/VISIONE/visual_odometry/libviso2/2010_03_09_drive_0019/I1_%06d.png&quot; index=0 num-buffers=-1  caps=&quot;image/png,framerate=\(fraction\)19/10\&quot; ! videorate framerate=19/10 ! pngdec ! ffmpegcolorspace"/>
</node>

this is the got message when I run "roslaunch my_file.launch --screen" :

[ WARN] [1350399215.805837395]: WARNING: you should specify camera info properties!

Note: If I run my gscam node without launch file it works properly (the argument is recognized):

rosrun gscam gscam /home/aldo/Projects/4thRC/BergamoComponents/services_caller/camera_parameters_to_set.txt
[ INFO] [1350399865.086125707]: INFO: you have set camera properties file: /home/aldo/Projects/4thRC/BergamoComponents/services_caller/camera_parameters_to_set.txt

How to fix it?

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Comments

Have you tried printing out how many and what arguments are passed? It might be that you're receiving more than 2 arguments from the launch file.

Ivan Dryanovski ( 2012-10-16 05:14:08 -0600 )edit

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answered 2012-10-16 05:13:47 -0600

dornhege

31395 ●134 ●284 ●498

updated 2012-10-16 06:28:55 -0600

Your argc condition is wrong. You don't account for the additional parameters that roslaunch gives the node.

Either change your condition or call ros::init before your code, if possible. That should filter out ROS arguments.

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answered 2012-10-16 05:26:06 -0600

aldo85ita
252 ●17 ●18 ●31

updated 2012-10-16 05:54:04 -0600

The solution is to count the number of arguments after ros::init :

ros::init(argc, argv, "gscam_publisher");
    if (argc != 2)
         {
            ROS_WARN("WARNING: you should specify camera info properties!");
         }else{
             ROS_INFO("INFO: you have set camera properties file: %s\n",argv[1]);
             camera_info_file=g_string_new(argv[1]);
         }

Because ROS add 2 further arguments to the node if you start it from the launch file. (I mean two arguments more than the basic rosnode command).

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You will need to elaborate on this condition. If you use roslaunch without args your condition will trigger the second case and assume __name:=gscam is the file. Better try calling ros::init before to remove the ROS arguments.

dornhege ( 2012-10-16 05:37:09 -0600 )edit

Thank you @dornhege, you're right! If you run condition code after ros::int I get the same number of arguments both in roslaunch and in rosnode executions. I'll public the code with solution, you can copy it in a new answer and I'll give you points for the right answer.

aldo85ita ( 2012-10-16 05:50:17 -0600 )edit

1

Please do not open answers for discussion or comments. This is not a forum. Instead, please either edit your original question or use the comment functionality.

Lorenz ( 2012-10-16 06:30:13 -0600 )edit

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answered 2018-01-24 15:10:49 -0600

Jacob
1

You can use ros::removeROSArgs(argc,argv,args) to strip out the command-line options added by ROS. It returns args, an std::vector<std::string> which should contain the program name followed by whatever arguments you passed.

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How to set arg to a node from launch file?

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