[Fix] Fix bug in `BackgroundPointsFilter` (#760)

* set gravity center origin

* remove filter transform in 3DSSD cfg

configs/3dssd/3dssd_4x4_kitti-3d-car.py

@@ -50,7 +50,8 @@ train_pipeline = [
         type='GlobalRotScaleTrans',
         rot_range=[-0.78539816, 0.78539816],
         scale_ratio_range=[0.9, 1.1]),
-    dict(type='BackgroundPointsFilter', bbox_enlarge_range=(0.5, 2.0, 0.5)),
+    # 3DSSD can get a higher performance without this transform
+    # dict(type='BackgroundPointsFilter', bbox_enlarge_range=(0.5, 2.0, 0.5)),
     dict(type='IndoorPointSample', num_points=16384),
     dict(type='DefaultFormatBundle3D', class_names=class_names),
     dict(type='Collect3D', keys=['points', 'gt_bboxes_3d', 'gt_labels_3d'])

mmdet3d/datasets/pipelines/transforms_3d.py

@@ -1194,10 +1194,10 @@ class BackgroundPointsFilter(object):
         enlarged_gt_bboxes_3d = gt_bboxes_3d_np.copy()
         enlarged_gt_bboxes_3d[:, 3:6] += self.bbox_enlarge_range
         points_numpy = points.tensor.clone().numpy()
-        foreground_masks = box_np_ops.points_in_rbbox(points_numpy,
-                                                      gt_bboxes_3d_np)
+        foreground_masks = box_np_ops.points_in_rbbox(
+            points_numpy, gt_bboxes_3d_np, origin=(0.5, 0.5, 0.5))
         enlarge_foreground_masks = box_np_ops.points_in_rbbox(
-            points_numpy, enlarged_gt_bboxes_3d)
+            points_numpy, enlarged_gt_bboxes_3d, origin=(0.5, 0.5, 0.5))
         foreground_masks = foreground_masks.max(1)
         enlarge_foreground_masks = enlarge_foreground_masks.max(1)
         valid_masks = ~np.logical_and(~foreground_masks,