Q: Subscribe to a Gazebo topic and publish in a ROS node
A: If you are working with that [turtlebot3 simulation](https://turtlebot3.readthedocs.io/en/latest/simulation.html), you don’t have to subscribe a gazebo topic, since the simulation is configured already with ROS.
To subscribe the laser scanner and publish something else in the same node, you can do the following:
Create a pkg with these dependencies
More ROS Learning Resources: https://goo.gl/DuTPtK
Q: How to add takeoff and land to teleop_twist_keyboard Python script?
Original question here: https://answers.ros.org/question/273938/adding-take-off-and-landing-into-teleop_twist_keyboardpy/
A: Here you can see an example script that does that.
RELATED LINKS:
* ROS Development Studio: rds.theconstructsim.com
* Robot Ignite Academy: www.robotigniteacademy.com
Q: How to use ira_laser_tools package to merge laser data
A: the reason why you cannot see in the /scan_multi the obstacles of the back is because you are using the default configuration of the ira_laser_tool. By default, the ira_laser_toolpackage does not produce the /scan_multi from -PI to +PI, but some other weird values.
The solution, is to use the rqt_reconfigure tool to set the angle_min and angle_max parameters to -PI and +PI respectively. To do that, open the tool with the command:
rosrun rqt_reconfigure rqt_reconfigure
You should see something like in the picture attached. Then, just change the angle values. I recommend you change that while watching the scan in rviz so you will see clearly how the scan changes based on your values.
The original question can be found here: https://answers.ros.org/question/273572/how-to-use-ira_laser_tools-package-to-merge-laser-datas/#273809
Q: I’m trying to assemble some readings from a Hokuyo laser simulated in gazebo.
A: The following example can help you understand how to use the laser_assembler package in order to assemble the readings from a Hokuyo laser.
Learn how to publish a blob detection in 2D in RVIZ through markers : https://answers.ros.org/question/273792/hi-i-wanto-to-meake-a-program-that-give-the-position-of-a-red-ball-in-2d-with-rviz/
Q:Hi, i wanto to meake a program that give the position of a red ball in 2D with rviz
A: So here you have very rudimentary solution. Of course you will need to add calibration procedures, and take extra thing into account like the blob area to get the distance value, but this I hope gives you a starting point.
So essentially you need to publish a Marker topic , with a Sphere Type of colour red. This marker will have to be referenced to your camera link or similar. I’ve done this Video as an example of how it could be done.