static_transform_publisher - coordinate transformation

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Good morning. I am currently working on a project to extract lanes from LiDAR scan (currently from a bag file) using PCL library. The main issue is that LiDAR is angled and picking up extra stuff (e.g. road barrels). I added static_transform_publisher node to have the point cloud leveled and was thinking of basically slicing it down to get rid of most of the extra noise. I can see transformation successfully in Rviz, but when I try to adjust the Cropbox, it looks like original coordinates are being used. At this point I am confused about what I am missing so that not only I have transformed point cloud, but also updated coordinates after transformation. Do I need to do conversion of coordinates separately?