# How to label 2D laser based map with some objects (door, bed, .... etc)

Hello

Im trying to put some labels of object like doors or beds in my yaml map. I have the map,its already created. Just want to define a object like for example door or bed in the map. The door should be label with some frame and coordinate, that later my laser scan can find them and give me some parameters like distance to this door or bed.

The “GMapping” package, which implements a simultaneous localization and mapping algorithm, has been employed to effectively learn occupancy grid maps from the 2D laser range data. The generated map can then be re-used to localize the platform in the learned environment producing the trajectories followed by the user.

Two dimensional map of the environment is already built from the laser range finder and IMU data. So I have that map.

This is my object node. So I put the object labels , coordinates here yes?

# include <vector>

sensor_msgs::LaserScan laser_scan; float min_range;

void scanCallback(const sensor_msgs::LaserScan::ConstPtr& msg) {

std::vector<float> laser;
laser = msg->ranges;

int size_laser = laser.size();
for (int i=0;i<size_laser;i++){
if (laser[i] < 0.01){
laser[i] = 99999;
}
if (laser[i] > 45){
laser[i] = 99999;
}
}

min_range = 2;
int index_min;
for (int i=0;i<size_laser;i++){
if (laser[i] < min_range){
min_range = laser[i];
index_min = i;
ROS_INFO("Minimum Range = %f", min_range);
}
}

for (int j=0;j<size_laser;j++){
if (laser[j] > min_range + 0.5){
laser[j] = 0;
}
}

laser_scan = *msg;
laser_scan.ranges.clear();
laser_scan.ranges = laser;


}

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

ros::init(argc, argv, "object_node");

ros::NodeHandle n;
ROS_INFO("Minimum Range = %f", min_range);
ros::Subscriber sub = n.subscribe("scan", 1000, scanCallback);

ros::Rate loop_rate(10);

while (ros::ok())
{

laser_pub.publish(laser_scan);

ros::spinOnce();

loop_rate.sleep();
}

return 0;


}

And this is the yaml map file

image: pow_real_time.pgm resolution: 0.050000 origin: [-100.000000, -100.000000, 0.000000] negate: 0 occupied_thresh: 0.65 free_thresh: 0.196

and this is my launch file

Perform AMCL localisation: runs several nodes to generate odometry from laser scans (ICP) & IMU, loads a map of the POW assessment area, runs AMCL, plays back a dataset for localisation, and runs the visualiser with the correct visualisation parameters configured. -->

<launch>

<node name="rosplay" pkg="rosbag" type="play" args="/home/Data/13-48-20.bag  --clock"/>

<node pkg="tf" type="static_transform_publisher" name="baselink_laser" args="0 0 0 0 0 0 /base_link /laser 10"/>
<node pkg="tf" type="static_transform_publisher" name="laser_imu" args="0 0 0 0 0 0 /laser /base_imu 10"/>
<node pkg="tf" type="static_transform_publisher" name="baselink_camera" args="0 0 0 0 0 0 /base_link /camera 10"/>

<!-- Start the map server node and specify the map file (*.pgm) and the map resolution in metres/pixel -->
<node name="map_server" pkg="map_server" type="map_server" args="\$(find amcl_listener)/maps/pow_real_time.yaml"         output="screen"/>

<!--Start the Laser_scan_matcher package, to provide odometry from laser data (ICP)-->
<node pkg="laser_scan_matcher" type ...
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@Astronaut Hi my name is Cris and im working on labeling obstacles and add semantic value to the map, could you finally manage to ad the labels to the map? And if you did how did you do it?? any help would be really helpful and appreciated

( 2013-08-22 09:33:01 -0600 )edit

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I think this strongly depends on what you are going to do. If you plan to use more knowledge about you environment and you also want to to reasoning about it, you could think of using a knowledge base like KnowRob ( http://www.ros.org/wiki/knowrob ) to store e.g. semantic environment information (in a so called semantic map) and also any other kind of information you want to use. A big advantage of this approach is that you can do reasoning about objects and the environment with ot like e.g. finding the most likely storage location of an object or similar (check the Knowrob Wiki: http://ias.cs.tum.edu/kb/wiki/index.php/Main_Page )

But if you just want to have some locations of objects in your environment, this might be a bit of an overkill, so in this case you might just stick with a list of objects and coordinates...

more

At the beginning I just want to have some locations of objects in my environment. So very very basic stuff. So how to put one object for beginning and label it with coordinate? Any tutorials about that? So just label an object with coordinates and frame in my environment.

( 2012-08-08 22:24:51 -0600 )edit

I guess in this case guess I would just write a ROS node that takes a list ob objects with coordinates and posts a TF transform for every object... You can check the TF tutorials about how to add transforms: http://www.ros.org/wiki/tf/Tutorials

( 2012-08-09 00:24:27 -0600 )edit

ok. So in that case i will have this object on the laser scan map and than can calculate some parameters like minimal distance to these objects. Wright?

( 2012-08-09 02:44:07 -0600 )edit

You will have tf transforms which can be in relation to every coordinate system known to tf (like e.g. the /map-frame). Thus you can easily calculate distances from the object poses to other coordinate systems (like e.g. that of the current robot pose) by just using the functions offered by TF

( 2012-08-09 03:11:52 -0600 )edit

Plus you can visualize your map and object positions using RVIZ

( 2012-08-09 03:21:35 -0600 )edit

ok. also can visualize single beams, like minimal distance to that object?

( 2012-08-09 03:32:28 -0600 )edit

So I can visualize the objects of my yaml map , right?

( 2012-08-09 03:35:40 -0600 )edit

And these object have to be put in the map. So have to fill my yaml map file with the object parameters?Or how it is?

( 2012-08-09 16:55:23 -0600 )edit