Hi there, I tried to use message_filters in order to synchronize a tfMessage and an Image messages in code like this:
message_filters::Subscriber<Image> image_sub;
message_filters::Subscriber<tf::tfMessage> tf_sub;
tf_sub.subscribe(nh_, "/tf", 1);
image_sub.subscribe(nh_, "image", 1);
TimeSynchronizer <Image, tf::tfMessage> sync(image_sub, tf_sub, 10);
Unfortunately it turns out that the compilation fails because the tfMessage has no Header block. Here is the error message: """ /opt/ros/diamondback/stacks/ros_comm/utilities/message_filters/include/message_filters/sync_policies/exact_time.h:126: error: ‘value’ is not a member of ‘ros::message_traits::TimeStamp<tf::tfmessage_<std::allocator<void> >, void>’ """
Would anyone know of an alternative to what I am trying to achieve above? Does tf_listener maybe support an option of returning the whole TF tree (tfMessage)?
thx and best, D.
Hey Dejan,
I found this solution to work for synchronizing point clouds and tf frames. I didn't try with Images but I don't see why the synchronization mechanism would be different. Note that I need to indicate the frame on which I synchronize (map in my case).
class PointReader
{
//Variables
tf::TransformListener tf_;
tf::MessageFilter<sensor_msgs::PointCloud2> * tf_filter_;
message_filters::Subscriber<sensor_msgs::PointCloud2> cloud2_sub_;
//initialisation
cloud2_sub_.subscribe(n, "/kinect/rgb/points2", 10);
tf_filter_ = new tf::MessageFilter<sensor_msgs::PointCloud2>(cloud2_sub_, tf_, "/map", 10);
tf_filter_->registerCallback( boost::bind(&PointReader::pointCloudCallback, this, _1) );
//callback
void pointCloudCallback(const sensor_msgs::PointCloud2::ConstPtr& sensor_msg)
{
ROS_INFO("Message received");
cloud_ = sensor_msg;
pcl::fromROSMsg (*cloud_, original_pcl_cloud_);
pcl::transformPointCloud("/map", original_pcl_cloud_, transformed_pcl_cloud_, tf_);
ROS_INFO("Message passed");
//transformed_pcl_cloud_ contains the projected cloud
}
}
Hope it helps
Raph
tully-
what we are trying to do in overall is to mask out parts of the robot in a view of a given camera. For that we have written a service server that takes in a tf tree, reads robot's urdf from a parameter server and essentially returns the robot's parts in white and everything else in black (see below). In a client program (http://tum-ros-pkg.svn.sourceforge.net/svnroot/tum-ros-pkg/perception/model_completion/src/getMask_ServiceClient.cpp) we would like to get a tf tree to pass it on as a request to the server and a time corresponding original image from the camera to obviously mask out the robot's parts.
Service server response:
Asked: 2011-03-02 11:26:17 -0500
Seen: 890 times
Last updated: Mar 04 '11
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