[Enhance] Sampling points based on distance metric (#667)

* [Enhance] Sampling points based on distance metric

* fix typo

* refine unittest

* refine unittest

* refine details & add unittest & refine configs

* remove __repr__ & rename arg

* fix unittest

* add unitest

* refine unittest

* refine code

* refine code

* refine depth calculation

* refine code

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

@@ -52,7 +52,7 @@ train_pipeline = [
         scale_ratio_range=[0.9, 1.1]),
     # 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='PointSample', num_points=16384),
     dict(type='DefaultFormatBundle3D', class_names=class_names),
     dict(type='Collect3D', keys=['points', 'gt_bboxes_3d', 'gt_labels_3d'])
 ]
@@ -78,7 +78,7 @@ test_pipeline = [
             dict(type='RandomFlip3D'),
             dict(
                 type='PointsRangeFilter', point_cloud_range=point_cloud_range),
-            dict(type='IndoorPointSample', num_points=16384),
+            dict(type='PointSample', num_points=16384),
             dict(
                 type='DefaultFormatBundle3D',
                 class_names=class_names,

configs/_base_/datasets/sunrgbd-3d-10class.py

@@ -20,7 +20,7 @@ train_pipeline = [
         rot_range=[-0.523599, 0.523599],
         scale_ratio_range=[0.85, 1.15],
         shift_height=True),
-    dict(type='IndoorPointSample', num_points=20000),
+    dict(type='PointSample', num_points=20000),
     dict(type='DefaultFormatBundle3D', class_names=class_names),
     dict(type='Collect3D', keys=['points', 'gt_bboxes_3d', 'gt_labels_3d'])
 ]
@@ -47,7 +47,7 @@ test_pipeline = [
                 sync_2d=False,
                 flip_ratio_bev_horizontal=0.5,
             ),
-            dict(type='IndoorPointSample', num_points=20000),
+            dict(type='PointSample', num_points=20000),
             dict(
                 type='DefaultFormatBundle3D',
                 class_names=class_names,

configs/imvotenet/imvotenet_stage2_16x8_sunrgbd-3d-10class.py

@@ -187,7 +187,7 @@ train_pipeline = [
         rot_range=[-0.523599, 0.523599],
         scale_ratio_range=[0.85, 1.15],
         shift_height=True),
-    dict(type='IndoorPointSample', num_points=20000),
+    dict(type='PointSample', num_points=20000),
     dict(type='DefaultFormatBundle3D', class_names=class_names),
     dict(
         type='Collect3D',
@@ -225,7 +225,7 @@ test_pipeline = [
                 sync_2d=False,
                 flip_ratio_bev_horizontal=0.5,
             ),
-            dict(type='IndoorPointSample', num_points=20000),
+            dict(type='PointSample', num_points=20000),
             dict(
                 type='DefaultFormatBundle3D',
                 class_names=class_names,

docs/tutorials/config.md

@@ -203,7 +203,7 @@ train_pipeline = [  # Training pipeline, refer to mmdet3d.datasets.pipelines for
         valid_cat_ids=(3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 24, 28, 33, 34,
                        36, 39),  # all valid categories ids
         max_cat_id=40),  # max possible category id in input segmentation mask
-    dict(type='IndoorPointSample',  # Sample indoor points, refer to mmdet3d.datasets.pipelines.indoor_sample for more details
+    dict(type='PointSample',  # Sample points, refer to mmdet3d.datasets.pipelines.transforms_3d for more details
             num_points=40000),  # Number of points to be sampled
     dict(type='IndoorFlipData',  # Augmentation pipeline that flip points and 3d boxes
         flip_ratio_yz=0.5,  # Probability of being flipped along yz plane
@@ -232,7 +232,7 @@ test_pipeline = [  # Testing pipeline, refer to mmdet3d.datasets.pipelines for m
         shift_height=True,  # Whether to use shifted height
         load_dim=6,  # The dimension of the loaded points
         use_dim=[0, 1, 2]),  # Which dimensions of the points to be used
-    dict(type='IndoorPointSample',  # Sample indoor points, refer to mmdet3d.datasets.pipelines.indoor_sample for more details
+    dict(type='PointSample',  # Sample points, refer to mmdet3d.datasets.pipelines.transforms_3d for more details
         num_points=40000),  # Number of points to be sampled
     dict(
         type='DefaultFormatBundle3D',  # Default format bundle to gather data in the pipeline, refer to mmdet3d.datasets.pipelines.formating for more details
@@ -286,7 +286,7 @@ data = dict(
                     valid_cat_ids=(3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 24,
                                    28, 33, 34, 36, 39),
                     max_cat_id=40),
-                dict(type='IndoorPointSample', num_points=40000),
+                dict(type='PointSample', num_points=40000),
                 dict(
                     type='IndoorFlipData',
                     flip_ratio_yz=0.5,
@@ -325,7 +325,7 @@ data = dict(
                 shift_height=True,
                 load_dim=6,
                 use_dim=[0, 1, 2]),
-            dict(type='IndoorPointSample', num_points=40000),
+            dict(type='PointSample', num_points=40000),
             dict(
                 type='DefaultFormatBundle3D',
                 class_names=('cabinet', 'bed', 'chair', 'sofa', 'table',
@@ -350,7 +350,7 @@ data = dict(
                 shift_height=True,
                 load_dim=6,
                 use_dim=[0, 1, 2]),
-            dict(type='IndoorPointSample', num_points=40000),
+            dict(type='PointSample', num_points=40000),
             dict(
                 type='DefaultFormatBundle3D',
                 class_names=('cabinet', 'bed', 'chair', 'sofa', 'table',

mmdet3d/core/points/base_points.py

@@ -281,6 +281,8 @@ class BasePoints(object):
                 Nonzero elements in the vector will be selected.
             4. `new_points = points[3:11, vector]`:
                 return a slice of points and attribute dims.
+            5. `new_points = points[4:12, 2]`:
+                return a slice of points with single attribute.
             Note that the returned Points might share storage with this Points,
             subject to Pytorch's indexing semantics.
 
@@ -303,6 +305,10 @@ class BasePoints(object):
                 item = list(item)
                 item[1] = list(range(start, stop, step))
                 item = tuple(item)
+            elif isinstance(item[1], int):
+                item = list(item)
+                item[1] = [item[1]]
+                item = tuple(item)
             p = self.tensor[item[0], item[1]]
 
             keep_dims = list(

mmdet3d/datasets/__init__.py

@@ -7,14 +7,17 @@ from .kitti_mono_dataset import KittiMonoDataset
 from .lyft_dataset import LyftDataset
 from .nuscenes_dataset import NuScenesDataset
 from .nuscenes_mono_dataset import NuScenesMonoDataset
+# yapf: disable
 from .pipelines import (BackgroundPointsFilter, GlobalAlignment,
                         GlobalRotScaleTrans, IndoorPatchPointSample,
                         IndoorPointSample, LoadAnnotations3D,
                         LoadPointsFromFile, LoadPointsFromMultiSweeps,
                         NormalizePointsColor, ObjectNameFilter, ObjectNoise,
-                        ObjectRangeFilter, ObjectSample, PointShuffle,
-                        PointsRangeFilter, RandomDropPointsColor, RandomFlip3D,
-                        RandomJitterPoints, VoxelBasedPointSampler)
+                        ObjectRangeFilter, ObjectSample, PointSample,
+                        PointShuffle, PointsRangeFilter, RandomDropPointsColor,
+                        RandomFlip3D, RandomJitterPoints,
+                        VoxelBasedPointSampler)
+# yapf: enable
 from .s3dis_dataset import S3DISSegDataset
 from .scannet_dataset import ScanNetDataset, ScanNetSegDataset
 from .semantickitti_dataset import SemanticKITTIDataset
@@ -30,9 +33,10 @@ __all__ = [
     'ObjectNoise', 'GlobalRotScaleTrans', 'PointShuffle', 'ObjectRangeFilter',
     'PointsRangeFilter', 'Collect3D', 'LoadPointsFromFile', 'S3DISSegDataset',
     'NormalizePointsColor', 'IndoorPatchPointSample', 'IndoorPointSample',
-    'LoadAnnotations3D', 'GlobalAlignment', 'SUNRGBDDataset', 'ScanNetDataset',
-    'ScanNetSegDataset', 'SemanticKITTIDataset', 'Custom3DDataset',
-    'Custom3DSegDataset', 'LoadPointsFromMultiSweeps', 'WaymoDataset',
-    'BackgroundPointsFilter', 'VoxelBasedPointSampler', 'get_loading_pipeline',
-    'RandomDropPointsColor', 'RandomJitterPoints', 'ObjectNameFilter'
+    'PointSample', 'LoadAnnotations3D', 'GlobalAlignment', 'SUNRGBDDataset',
+    'ScanNetDataset', 'ScanNetSegDataset', 'SemanticKITTIDataset',
+    'Custom3DDataset', 'Custom3DSegDataset', 'LoadPointsFromMultiSweeps',
+    'WaymoDataset', 'BackgroundPointsFilter', 'VoxelBasedPointSampler',
+    'get_loading_pipeline', 'RandomDropPointsColor', 'RandomJitterPoints',
+    'ObjectNameFilter'
 ]

mmdet3d/datasets/pipelines/__init__.py

@@ -9,10 +9,10 @@ from .test_time_aug import MultiScaleFlipAug3D
 from .transforms_3d import (BackgroundPointsFilter, GlobalAlignment,
                             GlobalRotScaleTrans, IndoorPatchPointSample,
                             IndoorPointSample, ObjectNameFilter, ObjectNoise,
-                            ObjectRangeFilter, ObjectSample, PointShuffle,
-                            PointsRangeFilter, RandomDropPointsColor,
-                            RandomFlip3D, RandomJitterPoints,
-                            VoxelBasedPointSampler)
+                            ObjectRangeFilter, ObjectSample, PointSample,
+                            PointShuffle, PointsRangeFilter,
+                            RandomDropPointsColor, RandomFlip3D,
+                            RandomJitterPoints, VoxelBasedPointSampler)
 
 __all__ = [
     'ObjectSample', 'RandomFlip3D', 'ObjectNoise', 'GlobalRotScaleTrans',
@@ -20,8 +20,9 @@ __all__ = [
     'Compose', 'LoadMultiViewImageFromFiles', 'LoadPointsFromFile',
     'DefaultFormatBundle', 'DefaultFormatBundle3D', 'DataBaseSampler',
     'NormalizePointsColor', 'LoadAnnotations3D', 'IndoorPointSample',
-    'PointSegClassMapping', 'MultiScaleFlipAug3D', 'LoadPointsFromMultiSweeps',
-    'BackgroundPointsFilter', 'VoxelBasedPointSampler', 'GlobalAlignment',
-    'IndoorPatchPointSample', 'LoadImageFromFileMono3D', 'ObjectNameFilter',
-    'RandomDropPointsColor', 'RandomJitterPoints'
+    'PointSample', 'PointSegClassMapping', 'MultiScaleFlipAug3D',
+    'LoadPointsFromMultiSweeps', 'BackgroundPointsFilter',
+    'VoxelBasedPointSampler', 'GlobalAlignment', 'IndoorPatchPointSample',
+    'LoadImageFromFileMono3D', 'ObjectNameFilter', 'RandomDropPointsColor',
+    'RandomJitterPoints'
 ]

mmdet3d/datasets/pipelines/transforms_3d.py

@@ -838,23 +838,26 @@ class ObjectNameFilter(object):
 
 
 @PIPELINES.register_module()
-class IndoorPointSample(object):
-    """Indoor point sample.
+class PointSample(object):
+    """Point sample.
 
     Sampling data to a certain number.
 
     Args:
-        name (str): Name of the dataset.
         num_points (int): Number of points to be sampled.
+        sample_range (float, optional): The range where to sample points.
     """
 
-    def __init__(self, num_points):
+    def __init__(self, num_points, sample_range=None, replace=False):
         self.num_points = num_points
+        self.sample_range = sample_range
+        self.replace = replace
 
-    def points_random_sampling(self,
+    def _points_random_sampling(self,
                                 points,
                                 num_samples,
-                               replace=None,
+                                sample_range=None,
+                                replace=False,
                                 return_choices=False):
         """Points random sampling.
 
@@ -863,20 +866,33 @@ class IndoorPointSample(object):
         Args:
             points (np.ndarray | :obj:`BasePoints`): 3D Points.
             num_samples (int): Number of samples to be sampled.
-            replace (bool): Whether the sample is with or without replacement.
+            sample_range (float, optional): Indicating the range where the
+                points will be sampled.
                 Defaults to None.
-            return_choices (bool): Whether return choice. Defaults to False.
-
+            replace (bool, optional): Sampling with or without replacement.
+                Defaults to None.
+            return_choices (bool, optional): Whether return choice.
+                Defaults to False.
         Returns:
             tuple[np.ndarray] | np.ndarray:
-
                 - points (np.ndarray | :obj:`BasePoints`): 3D Points.
                 - choices (np.ndarray, optional): The generated random samples.
         """
-        if replace is None:
+        if not replace:
             replace = (points.shape[0] < num_samples)
-        choices = np.random.choice(
-            points.shape[0], num_samples, replace=replace)
+        point_range = range(len(points))
+        if sample_range is not None and not replace:
+            # Only sampling the near points when len(points) >= num_samples
+            depth = np.linalg.norm(points.tensor, axis=1)
+            far_inds = np.where(depth > sample_range)[0]
+            near_inds = np.where(depth <= sample_range)[0]
+            point_range = near_inds
+            num_samples -= len(far_inds)
+        choices = np.random.choice(point_range, num_samples, replace=replace)
+        if sample_range is not None and not replace:
+            choices = np.concatenate((far_inds, choices))
+            # Shuffle points after sampling
+            np.random.shuffle(choices)
         if return_choices:
             return points[choices], choices
         else:
@@ -887,14 +903,23 @@ class IndoorPointSample(object):
 
         Args:
             input_dict (dict): Result dict from loading pipeline.
-
         Returns:
             dict: Results after sampling, 'points', 'pts_instance_mask' \
                 and 'pts_semantic_mask' keys are updated in the result dict.
         """
+        from mmdet3d.core.points import CameraPoints
         points = results['points']
-        points, choices = self.points_random_sampling(
-            points, self.num_points, return_choices=True)
+        # Points in Camera coord can provide the depth information.
+        # TODO: Need to suport distance-based sampling for other coord system.
+        if self.sample_range is not None:
+            assert isinstance(points, CameraPoints), \
+                'Sampling based on distance is only appliable for CAMERA coord'
+        points, choices = self._points_random_sampling(
+            points,
+            self.num_points,
+            self.sample_range,
+            self.replace,
+            return_choices=True)
         results['points'] = points
 
         pts_instance_mask = results.get('pts_instance_mask', None)
@@ -913,10 +938,29 @@ class IndoorPointSample(object):
     def __repr__(self):
         """str: Return a string that describes the module."""
         repr_str = self.__class__.__name__
-        repr_str += f'(num_points={self.num_points})'
+        repr_str += f'(num_points={self.num_points},'
+        repr_str += f' sample_range={self.sample_range})'
+
         return repr_str
 
 
+@PIPELINES.register_module()
+class IndoorPointSample(PointSample):
+    """Indoor point sample.
+
+    Sampling data to a certain number.
+    NOTE: IndoorPointSample is deprecated in favor of PointSample
+
+    Args:
+        num_points (int): Number of points to be sampled.
+    """
+
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            'IndoorPointSample is deprecated in favor of PointSample')
+        super(IndoorPointSample, self).__init__(*args, **kwargs)
+
+
 @PIPELINES.register_module()
 class IndoorPatchPointSample(object):
     r"""Indoor point sample within a patch. Modified from `PointNet++ <https://

tests/test_data/test_datasets/test_scannet_dataset.py

@@ -32,7 +32,7 @@ def test_getitem():
             type='PointSegClassMapping',
             valid_cat_ids=(3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 24, 28, 33,
                            34, 36, 39)),
-        dict(type='IndoorPointSample', num_points=5),
+        dict(type='PointSample', num_points=5),
         dict(
             type='RandomFlip3D',
             sync_2d=False,

tests/test_data/test_datasets/test_sunrgbd_dataset.py

@@ -28,7 +28,7 @@ def _generate_sunrgbd_dataset_config():
             rot_range=[-0.523599, 0.523599],
             scale_ratio_range=[0.85, 1.15],
             shift_height=True),
-        dict(type='IndoorPointSample', num_points=5),
+        dict(type='PointSample', num_points=5),
         dict(type='DefaultFormatBundle3D', class_names=class_names),
         dict(
             type='Collect3D',
@@ -73,7 +73,7 @@ def _generate_sunrgbd_multi_modality_dataset_config():
             rot_range=[-0.523599, 0.523599],
             scale_ratio_range=[0.85, 1.15],
             shift_height=True),
-        dict(type='IndoorPointSample', num_points=5),
+        dict(type='PointSample', num_points=5),
         dict(type='DefaultFormatBundle3D', class_names=class_names),
         dict(
             type='Collect3D',

tests/test_data/test_pipelines/test_augmentations/test_test_augment_utils.py

@@ -17,7 +17,7 @@ def test_multi_scale_flip_aug_3D():
         'sync_2d': False,
         'flip_ratio_bev_horizontal': 0.5
     }, {
-        'type': 'IndoorPointSample',
+        'type': 'PointSample',
         'num_points': 5
     }, {
         'type':

tests/test_data/test_pipelines/test_augmentations/test_transforms_3d.py

@@ -5,11 +5,12 @@ import torch
 
 from mmdet3d.core import (Box3DMode, CameraInstance3DBoxes,
                           DepthInstance3DBoxes, LiDARInstance3DBoxes)
+from mmdet3d.core.bbox import Coord3DMode
 from mmdet3d.core.points import DepthPoints, LiDARPoints
 from mmdet3d.datasets import (BackgroundPointsFilter, GlobalAlignment,
                               GlobalRotScaleTrans, ObjectNameFilter,
                               ObjectNoise, ObjectRangeFilter, ObjectSample,
-                              PointShuffle, PointsRangeFilter,
+                              PointSample, PointShuffle, PointsRangeFilter,
                               RandomDropPointsColor, RandomFlip3D,
                               RandomJitterPoints, VoxelBasedPointSampler)
 
@@ -705,3 +706,36 @@ def test_voxel_based_point_filter():
     assert pts_instance_mask.min() >= 0
     assert pts_semantic_mask.max() < 6
     assert pts_semantic_mask.min() >= 0
+
+
+def test_points_sample():
+    np.random.seed(0)
+    points = np.fromfile(
+        './tests/data/kitti/training/velodyne_reduced/000000.bin',
+        np.float32).reshape(-1, 4)
+    annos = mmcv.load('./tests/data/kitti/kitti_infos_train.pkl')
+    info = annos[0]
+    rect = torch.tensor(info['calib']['R0_rect'].astype(np.float32))
+    Trv2c = torch.tensor(info['calib']['Tr_velo_to_cam'].astype(np.float32))
+
+    points = LiDARPoints(
+        points.copy(), points_dim=4).convert_to(Coord3DMode.CAM, rect @ Trv2c)
+    num_points = 20
+    sample_range = 40
+    input_dict = dict(points=points)
+
+    point_sample = PointSample(
+        num_points=num_points, sample_range=sample_range)
+    sampled_pts = point_sample(input_dict)['points']
+
+    select_idx = np.array([
+        622, 146, 231, 444, 504, 533, 80, 401, 379, 2, 707, 562, 176, 491, 496,
+        464, 15, 590, 194, 449
+    ])
+    expected_pts = points.tensor.numpy()[select_idx]
+    assert np.allclose(sampled_pts.tensor.numpy(), expected_pts)
+
+    repr_str = repr(point_sample)
+    expected_repr_str = f'PointSample(num_points={num_points},'\
+                        + f' sample_range={sample_range})'
+    assert repr_str == expected_repr_str

tests/test_data/test_pipelines/test_indoor_pipeline.py

@@ -32,7 +32,7 @@ def test_scannet_pipeline():
             type='PointSegClassMapping',
             valid_cat_ids=(3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 24, 28, 33,
                            34, 36, 39)),
-        dict(type='IndoorPointSample', num_points=5),
+        dict(type='PointSample', num_points=5),
         dict(
             type='RandomFlip3D',
             sync_2d=False,
@@ -278,7 +278,7 @@ def test_sunrgbd_pipeline():
             rot_range=[-0.523599, 0.523599],
             scale_ratio_range=[0.85, 1.15],
             shift_height=True),
-        dict(type='IndoorPointSample', num_points=5),
+        dict(type='PointSample', num_points=5),
         dict(type='DefaultFormatBundle3D', class_names=class_names),
         dict(
             type='Collect3D', keys=['points', 'gt_bboxes_3d', 'gt_labels_3d']),

tests/test_data/test_pipelines/test_indoor_sample.py

 import numpy as np
 
 from mmdet3d.core.points import DepthPoints
-from mmdet3d.datasets.pipelines import (IndoorPatchPointSample,
-                                        IndoorPointSample,
+from mmdet3d.datasets.pipelines import (IndoorPatchPointSample, PointSample,
                                         PointSegClassMapping)
 
 
 def test_indoor_sample():
     np.random.seed(0)
-    scannet_sample_points = IndoorPointSample(5)
+    scannet_sample_points = PointSample(5)
     scannet_results = dict()
     scannet_points = np.array([[1.0719866, -0.7870435, 0.8408122, 0.9196809],
                                [1.103661, 0.81065744, 2.6616862, 2.7405548],
@@ -39,7 +38,7 @@ def test_indoor_sample():
                   scannet_semantic_labels_result)
 
     np.random.seed(0)
-    sunrgbd_sample_points = IndoorPointSample(5)
+    sunrgbd_sample_points = PointSample(5)
     sunrgbd_results = dict()
     sunrgbd_point_cloud = np.array(
         [[-1.8135729e-01, 1.4695230e+00, -1.2780589e+00, 7.8938007e-03],
@@ -58,7 +57,7 @@ def test_indoor_sample():
     sunrgbd_choices = np.array([2, 8, 4, 9, 1])
     sunrgbd_points_result = sunrgbd_results['points'].tensor.numpy()
     repr_str = repr(sunrgbd_sample_points)
-    expected_repr_str = 'IndoorPointSample(num_points=5)'
+    expected_repr_str = 'PointSample(num_points=5, sample_range=None)'
     assert repr_str == expected_repr_str
     assert np.allclose(sunrgbd_point_cloud[sunrgbd_choices],
                        sunrgbd_points_result)

tests/test_utils/test_points.py

@@ -193,6 +193,8 @@ def test_base_points():
         [[9.0722, 47.3678, -2.5382, 0.6666, 0.1956, 0.4974, 0.9409],
          [6.8547, 42.2509, -2.5955, 0.6565, 0.6248, 0.6954, 0.2538]])
     assert torch.allclose(expected_tensor, base_points[mask].tensor, 1e-4)
+    expected_tensor = torch.tensor([[0.6666], [0.1502], [0.6565], [0.2803]])
+    assert torch.allclose(expected_tensor, base_points[:, 3].tensor, 1e-4)
 
     # test length
     assert len(base_points) == 4
@@ -451,6 +453,8 @@ def test_cam_points():
         [[9.0722, 47.3678, -2.5382, 0.6666, 0.1956, 0.4974, 0.9409],
          [6.8547, 42.2509, -2.5955, 0.6565, 0.6248, 0.6954, 0.2538]])
     assert torch.allclose(expected_tensor, cam_points[mask].tensor, 1e-4)
+    expected_tensor = torch.tensor([[0.6666], [0.1502], [0.6565], [0.2803]])
+    assert torch.allclose(expected_tensor, cam_points[:, 3].tensor, 1e-4)
 
     # test length
     assert len(cam_points) == 4
@@ -725,6 +729,8 @@ def test_lidar_points():
         [[9.0722, 47.3678, -2.5382, 0.6666, 0.1956, 0.4974, 0.9409],
          [6.8547, 42.2509, -2.5955, 0.6565, 0.6248, 0.6954, 0.2538]])
     assert torch.allclose(expected_tensor, lidar_points[mask].tensor, 1e-4)
+    expected_tensor = torch.tensor([[0.6666], [0.1502], [0.6565], [0.2803]])
+    assert torch.allclose(expected_tensor, lidar_points[:, 3].tensor, 1e-4)
 
     # test length
     assert len(lidar_points) == 4
@@ -999,6 +1005,8 @@ def test_depth_points():
         [[9.0722, 47.3678, -2.5382, 0.6666, 0.1956, 0.4974, 0.9409],
          [6.8547, 42.2509, -2.5955, 0.6565, 0.6248, 0.6954, 0.2538]])
     assert torch.allclose(expected_tensor, depth_points[mask].tensor, 1e-4)
+    expected_tensor = torch.tensor([[0.6666], [0.1502], [0.6565], [0.2803]])
+    assert torch.allclose(expected_tensor, depth_points[:, 3].tensor, 1e-4)
 
     # test length
     assert len(depth_points) == 4