The Z-axis range of the point cloud does not match the Z-axis range of the BEV grid in occ related configs

[chenchen235]

I observed that point_cloud_range = [-51.2, -51.2, -5.0, 51.2, 51.2, 3.0], but grid_config = { 'x': [-40, 40, 0.4], 'y': [-40, 40, 0.4], 'z': [-1, 5.4, 6.4], 'depth': [1.0, 45.0, 0.5], } in occ related configs. Based on my understanding, the units for the Z-axis here should all be in meters. So what is the Z-axis offset between the point cloud coordinate system and the BEV coordinate system in physical space? Or, to be more precise: What is the corresponding range of the BEV grid's Z-axis in the point cloud space's Z-axis? Looking forward to your help.