lucaluca's profile - activity

Yeah you're right, I got confused, but if the tree is connected there's no need to tell ROS anything. Sorry :)

@syaz nyp fyp could you solve that?

I have another hypothesis: it could be that you have to somehow tell ROS that the transformation from /rgb_optical_frame to /map is the transformation /rgb_optical_frame->/odom->/map

It seems quite reasonable to me, because of the need I told you about before. Thanks a lot for the help ;)

@dornhege right, but after reading them from the parameter server I could delete them, right?

Yeah, but I don't want to force the user to insert also unnecessary values. So the two alternatives should be the one you suggested or using the parameter server, so that he can only set on the parameter server only the parameters he needs, right?

But in this way the user should set to "undefined" all the parameters he doesn't want to use.. Actually I thought about passing only the node handle as a parameter, so that using getParam() I can check which parameters the user decided to pass, but it doesn't seem a very clean solution..

So I have to add them to the service request? But I think in this case they become necessary, while I'd like to have a series of optional parameters, that the user can decide to pass or not..

@dornhege Ok, I was actually a little bit confused. So, I would like to allow the user to pass parameters as part of the service call, so that he can run the service once and make some trials calling it with different parameters. But how do I do this?

Hi,

It may seem a trivial question, but I couldn't find a good answer in the internet. I would like to write a service (NOT a node) that receives some parameters in input, but I couldn't find a way to pass them that is similar to what you could do with a node (where you retrieve the parameters through the node handler). The only way seems to use the parameter server, but if possible I would prefer to avoid using those kind of "global variables". Any suggestions?

It modifies currentVelocityCommand accordingly to the parameters passed to the function, but it doesn't actually publish anything, it just modifies the content of currentVelocityCommand. In my opinion, there must be somewhere else some code that really publishes currentVelocityCommand to some rostopic: you could publish currentVelocityCommand at a publishing rate suitable for your goal and modify from time to time its content with this function.

@l0g1x this is reasonable but it didn't seem to solve my problem. However, I'm very busy right now, so I will let you know in few days ;)

Hi, I'm trying to get this package in order to use it or port it to the newest ROS version:

http://wiki.ros.org/polar_scan_matcher

However, I could only find this, which seems to be basically only the scan matching function without the wrapper, which could save me a lot of time:

http://www.irrc.monash.edu.au/adiosi/...

Do you know where I can find the wrapper? The github archive points to a library that only seems to be using CSM by Andrea Censi to do the scan matching and not polar scan matching.

@Orso since the help file of rosbag record says "Record a bag file with the contents of specified topics" and it seems there's not a topic with your data, I'm assuming this cannot be done directly. You can wait to see if some other user knows a direct approach :)

I don't know if this is the best approach, but it should work. I would write a node that publishes the transformations between /map and /base_link. In order to get the transformation you should use "lookupTransform" as you can see here:

http://wiki.ros.org/tf/Tutorials/Writ...

As you can see, the transformation can be published to a topic of your choice. Whatever it is, you can then use this command in order to record it:

rosbag record -O subset /chosentopic

@l0g1x that was what I was doing, but it didn't make any difference. But I have a couple news that I'm going to add right now at the bottom of the question

I added a couple details to the question

@l0g1x thought the same, but I don't know how to solve the problem. The parameter "use_sim_time" should have solved it. However, I'm not passing the timestamps from the bag file, but I'm just using "rosbag play". Should I change the way I'm working?

Hi, I'm following this tutorial: http://wiki.ros.org/laser_pipeline/Tu...

However, I cannot see the point cloud if I try to reproduce a bagfile and in the console in which I launched the node that should convert the laser scans into a point cloud I'm getting a lot of messages like:

TF_OLD_DATA ignoring data from the past

I already used this command that should have solved the problem:

rosparam set use_sim_time true

Any ideas about how to solve this problem?

EDIT: I want to add a couple details. This is the exact error:

at line 260 in /tmp/buildd/ros-hydro-tf2-0.4.10-0precise-20140304-0005/src/buffer_core.cpp Warning: TF_OLD_DATA ignoring data from the past for frame wide_stereo_optical_frame at time 1.275e+09 according to authority /play_1407416604376477595 Possible reasons are listed at http://wiki.ros.org/tf/Errors 1.336857e-312xplained

The bagfile I'm using is the bagfile of this tutorial: http://wiki.ros.org/laser_assembler/T...

Apart from setting use_sim_time to true, I also used the "--clock" parameter when playing the bagfile. I noticed a couple interesting things:

1) the first time I launch the bag file, no error pops out in the console window of the converting node. They come out from the second run on.

2) I launched the command "rosrun tf tf_monitor odom_combined base_link" and I saw that the results were "avg = 0.0826798: max = 0.155032" that seem a little bit too high, but raising the tolerance to 1 second didn't make any difference.

I'm trying to follow this tutorial using ROS hydro medusa:

/laser_pipeline/Tutorials/IntroductionToWorkingWithLaserScannerData

The code won't compile saying that:

/opt/ros/hydro/include/laser_geometry/laser_geometry.h:46:22: fatal error: Eigen/Core: No such file or directory

I could only find a guide for a migration to ROS fuerte, but those instructions didn't work for me. Does anybody know how to fix this?

EDIT to add details: I created a new package with dependences on roscpp, rospy (probably useless) and std_msgs. I'm using ROS hydro medusa. I then created a cpp source containing this code:

#include "ros/ros.h"
#include "tf/transform_listener.h"
#include "sensor_msgs/PointCloud.h"
#include "tf/message_filter.h"
#include "message_filters/subscriber.h"
#include "laser_geometry/laser_geometry.h"

class LaserScanToPointCloud{

public:

  ros::NodeHandle n_;
  laser_geometry::LaserProjection projector_;
  tf::TransformListener listener_;
  message_filters::Subscriber<sensor_msgs::LaserScan> laser_sub_;
  tf::MessageFilter<sensor_msgs::LaserScan> laser_notifier_;
  ros::Publisher scan_pub_;

  LaserScanToPointCloud(ros::NodeHandle n) : 
    n_(n),
    laser_sub_(n_, "base_scan", 10),
    laser_notifier_(laser_sub_,listener_, "base_link", 10)
  {
    laser_notifier_.registerCallback(
      boost::bind(&LaserScanToPointCloud::scanCallback, this, _1));
    laser_notifier_.setTolerance(ros::Duration(0.01));
    scan_pub_ = n_.advertise<sensor_msgs::PointCloud>("/my_cloud",1);
  }

  void scanCallback (const sensor_msgs::LaserScan::ConstPtr& scan_in)
  {
    sensor_msgs::PointCloud cloud;
    try
    {
        projector_.transformLaserScanToPointCloud(
          "base_link",*scan_in, cloud,listener_);
    }
    catch (tf::TransformException& e)
    {
        std::cout << e.what();
        return;
    }

    // Do something with cloud.

    scan_pub_.publish(cloud);

  }
};

int main(int argc, char** argv)
{

  ros::init(argc, argv, "my_scan_to_cloud");
  ros::NodeHandle n;
  LaserScanToPointCloud lstopc(n);

  ros::spin();

  return 0;
}

At this point, I added these two lines at the end of CMakeLists.txt as I always did with sources:

add_executable(laser_scan_to_point_cloud src/laser_scan_to_point_cloud.cpp)
target_link_libraries(laser_scan_to_point_cloud ${catkin_LIBRARIES})

However, I'm getting the error that I told you when I try to compile with catkin_make. I tried to use rosdep, but it says that all the dependencies have been correctly installed. I also tried with an offline roswtf, but it doesn't find anything. Here are the versions:

rosversion -d: hydro

rosversion roscpp: 1.10.2

rosversion laser_geometry: 1.5.15

rosversion std_msgs: 0.5.8

Please let me know if you need other information!

@allenh1 my fault, I forgot to import the tf library. Thanks a lot!! :)