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2016-06-02 04:56:51 -0600 asked a question How to Block all publishers

Hi I currently have a mobile platform, would like to create a publisher to latch on at the velocity topic of the platform, and prevent all other nodes from publishing to it, effectively creating a kill switch to the platform. As the platform will perform the latest twist msg sent to it, so I'm hoping to flood it with it with an infinite loops of zeros twist to get the platform to stop moving.

Best regards Jhlim6

2016-05-23 22:34:08 -0600 asked a question Could not find "tf_conversions" package configuration file


I was compiling a ROS node in my raspberry pi (fresh install) and there is a cmake error. I'm using the raspberry in headless mode. The node complied successfully in my computer though.

CMake Error at /opt/ros/indigo/share/catkin/cmake/catkinConfig.cmake:83 (find_package) :
Could not find a package configuration file provided by "tf_conversions" with any of the following names:

Call Stack
    maven_odo/CMakeLists.tst:4 (find_package)

Thank you for helping

Much appreciated. James

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2016-02-17 23:54:12 -0600 commented question camerainfo different from the definition ros document

hi ahendrix, the document i'm referring to is

2016-02-17 21:44:55 -0600 asked a question camerainfo different from the definition ros document


I notice that when I echo out the camerainfo, left and right, I received a different Projection matrix than what is expected from ros doc.

P: [1.470061237672634, 0.0, 0.558421063485309, 0.0,
1.470061237672634, 0.5224868333963834, 0.0, 0.0,
1.0, 0.0, 0.0, 0.0]
P [fx' 0 cx' Tx]
= [ 0 fy' cy' Ty]
[ 0 0 1 0]

also what is the do_rectify under the section ROI of camerainfo

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2016-02-11 06:37:30 -0600 commented answer PCL removing outliers using radius as condition

I used rviz to note that the pointcloud was present prior to filtering. It output the cloud details before filtering, but after that it hangs.

2016-02-11 06:04:42 -0600 commented answer PCL removing outliers using radius as condition

Mistake when pasting the code. Statistical outlier removal works for me. But it doesn't fully remove all the noise.

2016-02-11 03:43:39 -0600 asked a question PCL removing outliers using radius as condition

Hi I'm using a radius filter to remove outliers from my pointcloud, however the code hangs while creating the filtering object. The code never gotten to the point of outputting the message "cloud after filtering".

   std::cerr << "Cloud before statistical filtering: " << std::endl;
   std::cerr << PCL1_temp_cloud << std::endl;
   // Create the filtering object
   pcl::RadiusOutlierRemoval<pcl::pointxyz> outrem;
   outrem.setMinNeighborsInRadius (2);
   outrem.filter (PCL1_cloud_filtered);
   std::cerr << "Cloud after filtering: " << std::endl;   // code stops before this point
   std::cerr << PCL1_cloud_filtered << std::endl;
   pcl::toROSMsg    (PCL1_cloud_filtered, output);

2016-02-11 02:10:10 -0600 asked a question Filtering pointcloud with voxel grid giving different number of data points

Hi, I try using the voxel grid filter on a pointcloud generated by the Ensenso camera. While the camera is held stationary, it gives a constant number of data points, however with a voxel grid filter of 0.01f (1cm). I've been received different number of data points back. Why is this the case.

      std::cerr << "PointCloud before filtering: " << cloud_blob->width * cloud_blob->height << " data points." << std::endl;
      // Create the filtering object: downsample the dataset using a leaf size of 1cm
      pcl::VoxelGrid<pcl::pclpointcloud2> sor;
      sor.setInputCloud (cloud_blob);
      sor.setLeafSize (0.01f, 0.01f, 0.01f);
      sor.filter (cloud_filtered_blob);           //pcd saved in cloud_filtered_blob
      pcl::fromPCLPointCloud2 (cloud_filtered_blob, *cloud_filtered); 
std::cerr << "PointCloud after filtering: " << cloud_filtered->width * cloud_filtered->height << " data points." << std::endl;

2016-02-11 01:53:01 -0600 commented answer memory corruption

Thanks, I just realized that line 3 is the critical line, not line 4. That solved my problem of double freeing pointers.

2016-02-11 01:32:13 -0600 commented answer memory corruption

hi, I have the same error msg. How do you use CloudConstPtr cloud () ? I got CloudConstPtr was not declared when i tried to use it

2016-02-10 00:20:01 -0600 commented answer subscribe to sensor_msg::PointCloud2

Hi, Its not obvious to me, but why does the ros subscriber fails in the while loop?

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2016-02-04 03:27:51 -0600 commented question Trouble subscribing to pointclouds

Hi NEngelhard,

I realized that my code is not so comprehensible here, so I asked another qns where i posted the test code.

2016-02-04 03:24:34 -0600 asked a question subscribe to sensor_msg::PointCloud2

Hi, my ros subscriber is having trouble entering the callback. I'm using ROS_INFO to tell me if the callback is in. In the rqt_graph, it shows that the subscriber node is subscribed to the topic that the publisher is publishing. Using rostopic echo "topic", it is displaying a lots of numbers that i'm presuming that it is the pointcloud.

below is my code.


typedef pcl::PointCloud<pcl::PointXYZ> PointCloud;

int main(int argc, char** argv) {
 ros::init (argc, argv, "pub_pcl");
 ros::Publisher pub;
 pub = nh.advertise<sensor_msgs::PointCloud2> ("input_cloud", 1);
 pcl::PCLPointCloud2::Ptr cloud_blob (new pcl::PCLPointCloud2);
 pcl::PCDReader reader; (argv[1], *cloud_blob);
 sensor_msgs::PointCloud2 output;
 pcl_conversions::fromPCL(*cloud_blob, output);
 ros::Rate loop_rate(10);
 while (nh.ok())
   pub.publish (output);
   ros::spinOnce ();
   loop_rate.sleep ();


void cloud_callback (const sensor_msgs::PointCloud2ConstPtr& cloud_msg){
 ROS_INFO("inside callback");

int main (int argc, char** argv) {
 ros::init (argc, argv, "cloud_sub");
 ros::NodeHandle nh;
 ros::Rate loop_rate(10);
 ros::Subscriber sub;
 while (nh.ok()) {
   sub = nh.subscribe ("input_cloud", 1, cloud_callback);
   ros::spinOnce ();
   loop_rate.sleep ();
2016-02-04 02:12:59 -0600 asked a question Trouble subscribing to pointclouds

Hi, I am having troubling using the ROS's sensor_msg to send pointclouds over nodes. From RVIS, i can see the pointcloud being published, and the rqt_graph shows that the subscriber has subscribed to the publisher, but the subscriber is not entering the subscriber callback function.

Please help. I've also tried sending pointclouds directly following example, but the same issue arises.

Below is my code using sensor_msgs

ros::Subscriber sub = nh.subscribe<sensor_msgs::pointcloud2>("/ensenso/depth/points", 2, callback); void callback(const sensor_msgs::PointCloud2ConstPtr& cloud) { ROS_INFO ("inside callback"); }

void sender ( const boost::shared_ptr<pcl::pointcloud<pcl::pointxyz> >& cloud) { sensor_msgs::PointCloud2 cloud_msg; pcl::toROSMsg (* cloud, cloud_msg); cloud_pub_.publish(cloud_msg); }