How to crop the point cloud obtained by livox mid 360?

[BJHYZJ]

I mounted the mid360 horizontally on the chassis, and there is a robotic arm mounted behind the mid360, so I want to limit the point cloud output by mid360, for example, only the first 180 degrees of the point cloud, how can this be done?

[BJHYZJ]

I found a parameter called "fov degree" and tried changing it from 360 to 180, but it didn’t work. In the visualization interface, it still shows point clouds across almost all angles.