how voxel is different from obstacle-layer and why it should be used with global costamp i also included it in the params but i noticed that nothing changes so what does ir represents ?
Hi @80601 ,
To understand a Voxel, you need to understand Pixel first.
Pixel is short for Picture Element, while Voxel is short for Volume Element.
Pixel is in 2D plane, while Voxel is in 3D Plane.
Now coming to ROS Navigation, Obstacle Layer and Voxel Layer are technically the same, when it comes to the functionality, but Obstacle layer operates in 2D using Pixels while Voxel Layer operates in 3D using 3D Pixels, also known as Voxel.
You would use Obstacle Layer when your Scanner operates in 2D, such as a Laser Scanner that utilizes LaserScan message type. You would use Voxel Layer when your Scanner operates in 3D, such as a Laser Scanner that utilizes PointCloud message type.
When you use both of them together, that is, if you have both of them enabled, only one of them will function - based on what type of sensor you have mounted on the robot. If you have a 2D laser scanner you may not have a 3D laser scanner, similarly when you have a 3D scanner, you will not have a 2D scanner. Therefore, you will not, in most cases, use both the Obstacle and Voxel Layer.
Since you have a 2D laser scanner and you have enabled Voxel Layer, you notice no significant changes because you do not have a 3D sensor. Thus your Global Costmap utilizes only the Obstacle Layer.
I hope this clarifies your doubt(s).
Regards,
Girish