BEV grid resolution

Hello dear blogger, thank you very much for your great work. I modified the corresponding parameters in the bev_stereo_lss_r50_256x704_128x128_24e_2key.py file according to this #146 for get 256x256 bev grid resolution. Specifically include
`backbone_conf：
1，x_bound: [-51.2, 51.2, 0.8]-->:[-51.2, 51.2, 0.4];
2, y_bound: [-51.2, 51.2, 0.8]-->:[-51.2, 51.2, 0.4];
bbox_coder：
1， out_size_factor=4 --> 2,
2, voxel_size=[0.2, 0.2, 8] --> [0.1, 0.1, 8];
train_cfg：
1， out_size_factor=4 --> 2,
2, voxel_size=[0.2, 0.2, 8] --> [0.1, 0.1, 8];
test_cfg：
1， out_size_factor=4 --> 2,
2, voxel_size=[0.2, 0.2, 8] --> [0.1, 0.1, 8];',Other than that there are no changes.
But there is no result at all, that is, mAP=0. In addition to this, do you need to modify the parameters? Or is there still something in the test code that needs to be modified?

Start with configs/bev_stereo_lss_r50_256x704_128x128_24e_2key.py and compare the changed backbone_conf, bbox_coder, train_cfg, and test_cfg values with issue #146. Then trace the test configuration and evaluation path to determine which settings affect the zero mAP result. Done means identifying the additional required changes or confirming the correct configuration for a 256x256 BEV grid.