[Enhance] Dataset browse for multiple dataset types (#467)

* fix small bug in get_loading_pipeline()

* adopt eval_pipeline & support seg visualization

* support multi-modality vis

* fix small bugs

* add multi-modality args & support S3DIS vis

* update docs with imgs

* fix typos

docs/useful_tools.md

@@ -86,21 +86,29 @@ Or you can use 3D visualization software such as the [MeshLab](http://www.meshla
 
 ## Dataset
 
-To browse the KITTI directly without inference, you can run the following command
+We also provide scripts to visualize the dataset without inference. You can use `tools/misc/browse_dataset.py` to show loaded data and ground-truth online and save them on the disk. Currently we support single-modality 3D detection and 3D segmentation on all the datasets, as well as multi-modality 3D detection on KITTI and SUN RGB-D. To browse the KITTI dataset, you can run the following command
 
 ```shell
-python tools/misc/browse_dataset.py ${CONFIG_FILE} --output-dir ${OUTPUT_DIR}
+python tools/misc/browse_dataset.py configs/_base_/datasets/kitti-3d-3class.py --output-dir ${OUTPUT_DIR} --online
 ```
 
-Sample config can be found in `configs/_base_/datasets/` folder.
+**Notice**: Once specifying `--output-dir`, the images of views specified by users will be saved when pressing `_ESC_` in open3d window. If you don't have a monitor, you can remove the `--online` flag to only save the visualization results and browse them offline.
 
-E.g.,
+If you also want to show 2D images with 3D bounding boxes projected onto them, you need to find a config that supports multi-modality data loading, and then add the `--multi-modality` flag to the command. An example is showed below
+
+```shell
+python tools/misc/browse_dataset.py configs/mvxnet/dv_mvx-fpn_second_secfpn_adamw_2x8_80e_kitti-3d-3class.py --output-dir ${OUTPUT_DIR} --online --multi-modality
+```
+
+![Open3D_visualization](../resources/browse_dataset_multi_modality.png)
+
+You can simply browse different datasets using different configs, e.g. visualizing the ScanNet dataset in 3D semantic segmentation task
 
 ```shell
-python tools/misc/browse_dataset.py configs/_base_/datasets/kitti-3d-3class.py
+python tools/misc/browse_dataset.py configs/_base_/datasets/scannet_seg-3d-20class.py --output-dir ${OUTPUT_DIR} --online
 ```
 
-**Notice**: Once specifying `--output-dir`, the images of views specified by users will be saved when pressing _ESC_ in open3d window.
+![Open3D_visualization](../resources/browse_dataset_seg.png)
 
  
 

mmdet3d/datasets/utils.py

@@ -15,6 +15,9 @@ from mmdet.datasets.pipelines import LoadImageFromFile
 def is_loading_function(transform):
     """Judge whether a transform function is a loading function.
 
+    Note: `MultiScaleFlipAug3D` is a wrapper for multiple pipeline functions,
+    so we need to search if its inner transforms contain any loading function.
+
     Args:
         transform (dict | :obj:`Pipeline`): A transform config or a function.
 
@@ -34,7 +37,7 @@ def is_loading_function(transform):
             return False
         if obj_cls in loading_functions:
             return True
-        if obj_cls in (MultiScaleFlipAug3D):
+        if obj_cls in (MultiScaleFlipAug3D, ):
             return None
     elif callable(transform):
         if isinstance(transform, loading_functions):

tools/misc/browse_dataset.py

 import argparse
+import numpy as np
+import warnings
 from mmcv import Config, DictAction, mkdir_or_exist, track_iter_progress
 from os import path as osp
 
-from mmdet3d.core.bbox import Box3DMode, Coord3DMode
-from mmdet3d.core.visualizer.open3d_vis import Visualizer
-from mmdet3d.datasets import build_dataset, get_loading_pipeline
+from mmdet3d.core.bbox import (Box3DMode, Coord3DMode, DepthInstance3DBoxes,
+                               LiDARInstance3DBoxes)
+from mmdet3d.core.visualizer import (show_multi_modality_result, show_result,
+                                     show_seg_result)
+from mmdet3d.datasets import build_dataset
 
 
 def parse_args():
@@ -21,6 +25,17 @@ def parse_args():
         default=None,
         type=str,
         help='If there is no display interface, you can save it')
+    parser.add_argument(
+        '--multi-modality',
+        action='store_true',
+        help='Whether to visualize multi-modality data. If True, we will show '
+        'both 3D point clouds with 3D bounding boxes and 2D images with '
+        'projected bounding boxes.')
+    parser.add_argument(
+        '--online',
+        action='store_true',
+        help='Whether to perform online visualization. Note that you often '
+        'need a monitor to do so.')
     parser.add_argument(
         '--cfg-options',
         nargs='+',
@@ -35,7 +50,8 @@ def parse_args():
     return args
 
 
-def retrieve_data_cfg(config_path, skip_type, cfg_options):
+def build_data_cfg(config_path, skip_type, cfg_options):
+    """Build data config for loading visualization data."""
     cfg = Config.fromfile(config_path)
     if cfg_options is not None:
         cfg.merge_from_dict(cfg_options)
@@ -43,64 +59,173 @@ def retrieve_data_cfg(config_path, skip_type, cfg_options):
     if cfg.get('custom_imports', None):
         from mmcv.utils import import_modules_from_strings
         import_modules_from_strings(**cfg['custom_imports'])
+    # extract inner dataset of `RepeatDataset` as `cfg.data.train`
+    # so we don't need to worry about it later
     if cfg.data.train['type'] == 'RepeatDataset':
-        train_data_cfg = cfg.data.train.dataset
-    else:
+        cfg.data.train = cfg.data.train.dataset
     train_data_cfg = cfg.data.train
+    # eval_pipeline purely consists of loading functions
+    # use eval_pipeline for data loading
     train_data_cfg['pipeline'] = [
-        x for x in train_data_cfg.pipeline if x['type'] not in skip_type
+        x for x in cfg.eval_pipeline if x['type'] not in skip_type
     ]
 
     return cfg
 
 
+def to_depth_mode(points, bboxes):
+    """Convert points and bboxes to Depth Coord and Depth Box mode."""
+    if points is not None:
+        points = Coord3DMode.convert_point(points.copy(), Coord3DMode.LIDAR,
+                                           Coord3DMode.DEPTH)
+    if bboxes is not None:
+        bboxes = Box3DMode.convert(bboxes.clone(), Box3DMode.LIDAR,
+                                   Box3DMode.DEPTH)
+    return points, bboxes
+
+
+def show_det_data(idx, dataset, out_dir, filename, show=False):
+    """Visualize 3D point cloud and 3D bboxes."""
+    example = dataset.prepare_train_data(idx)
+    points = example['points']._data.numpy()
+    gt_bboxes = dataset.get_ann_info(idx)['gt_bboxes_3d'].tensor
+    if dataset.box_mode_3d != Box3DMode.DEPTH:
+        points, gt_bboxes = to_depth_mode(points, gt_bboxes)
+    show_result(
+        points,
+        gt_bboxes.clone(),
+        None,
+        out_dir,
+        filename,
+        show=show,
+        snapshot=True)
+
+
+def show_seg_data(idx, dataset, out_dir, filename, show=False):
+    """Visualize 3D point cloud and segmentation mask."""
+    example = dataset.prepare_train_data(idx)
+    points = example['points']._data.numpy()
+    gt_seg = example['pts_semantic_mask']._data.numpy()
+    show_seg_result(
+        points,
+        gt_seg.copy(),
+        None,
+        out_dir,
+        filename,
+        np.array(dataset.PALETTE),
+        dataset.ignore_index,
+        show=show,
+        snapshot=True)
+
+
+def show_proj_bbox_img(idx, dataset, out_dir, filename, show=False):
+    """Visualize 3D bboxes on 2D image by projection."""
+    example = dataset.prepare_train_data(idx)
+    gt_bboxes = dataset.get_ann_info(idx)['gt_bboxes_3d']
+    img_metas = example['img_metas']._data
+    img = example['img']._data.numpy()
+    # need to transpose channel to first dim
+    img = img.transpose(1, 2, 0)
+    # no 3D gt bboxes, just show img
+    if gt_bboxes.tensor.shape[0] == 0:
+        gt_bboxes = None
+    if isinstance(gt_bboxes, DepthInstance3DBoxes):
+        show_multi_modality_result(
+            img,
+            gt_bboxes,
+            None,
+            example['calib'],
+            out_dir,
+            filename,
+            depth_bbox=True,
+            img_metas=img_metas,
+            show=show)
+    elif isinstance(gt_bboxes, LiDARInstance3DBoxes):
+        show_multi_modality_result(
+            img,
+            gt_bboxes,
+            None,
+            img_metas['lidar2img'],
+            out_dir,
+            filename,
+            depth_bbox=False,
+            img_metas=img_metas,
+            show=show)
+    else:
+        # can't project, just show img
+        show_multi_modality_result(
+            img, None, None, None, out_dir, filename, show=show)
+
+
+def is_multi_modality(dataset):
+    """Judge whether a dataset loads multi-modality data (points+img)."""
+    if not hasattr(dataset, 'modality') or dataset.modality is None:
+        return False
+    if dataset.modality['use_camera']:
+        # even dataset with `use_camera=True` may not load img
+        # should check its loaded data
+        example = dataset.prepare_train_data(0)
+        if 'img' in example.keys():
+            return True
+    return False
+
+
 def main():
     args = parse_args()
 
     if args.output_dir is not None:
         mkdir_or_exist(args.output_dir)
 
-    cfg = retrieve_data_cfg(args.config, args.skip_type, args.cfg_options)
-    if cfg.data.train['type'] == 'RepeatDataset':
-        cfg.data.train.dataset['pipeline'] = get_loading_pipeline(
-            cfg.train_pipeline)
-    else:
-        cfg.data.train['pipeline'] = get_loading_pipeline(cfg.train_pipeline)
+    cfg = build_data_cfg(args.config, args.skip_type, args.cfg_options)
+    try:
         dataset = build_dataset(
             cfg.data.train, default_args=dict(filter_empty_gt=False))
-    # For RepeatDataset type, the infos are stored in dataset.dataset
-    if cfg.data.train['type'] == 'RepeatDataset':
-        dataset = dataset.dataset
+    except TypeError:  # seg dataset doesn't have `filter_empty_gt` key
+        dataset = build_dataset(cfg.data.train)
     data_infos = dataset.data_infos
+    dataset_type = cfg.dataset_type
+
+    # configure visualization mode
+    vis_type = 'det'  # single-modality detection
+    if dataset_type in ['ScanNetSegDataset', 'S3DISSegDataset']:
+        vis_type = 'seg'  # segmentation
+    multi_modality = args.multi_modality
+    if multi_modality:
+        # check whether dataset really supports multi-modality input
+        if not is_multi_modality(dataset):
+            warnings.warn(
+                f'{dataset_type} with current config does not support multi-'
+                'modality data loading, only show point clouds here')
+            multi_modality = False
 
     for idx, data_info in enumerate(track_iter_progress(data_infos)):
-        if cfg.dataset_type in ['KittiDataset', 'WaymoDataset']:
+        if dataset_type in ['KittiDataset', 'WaymoDataset']:
             pts_path = data_info['point_cloud']['velodyne_path']
-        elif cfg.dataset_type in ['ScanNetDataset', 'SUNRGBDDataset']:
+        elif dataset_type in [
+                'ScanNetDataset', 'SUNRGBDDataset', 'ScanNetSegDataset',
+                'S3DISSegDataset'
+        ]:
             pts_path = data_info['pts_path']
-        elif cfg.dataset_type in ['NuScenesDataset', 'LyftDataset']:
+        elif dataset_type in ['NuScenesDataset', 'LyftDataset']:
             pts_path = data_info['lidar_path']
         else:
             raise NotImplementedError(
-                f'unsupported dataset type {cfg.dataset_type}')
-        file_name = osp.splitext(osp.basename(pts_path))[0]
-        save_path = osp.join(args.output_dir,
-                             f'{file_name}.png') if args.output_dir else None
+                f'unsupported dataset type {dataset_type}')
 
-        example = dataset.prepare_train_data(idx)
-        points = example['points']._data.numpy()
-        points = Coord3DMode.convert_point(points, Coord3DMode.LIDAR,
-                                           Coord3DMode.DEPTH)
-        gt_bboxes = dataset.get_ann_info(idx)['gt_bboxes_3d'].tensor
-        if gt_bboxes is not None:
-            gt_bboxes = Box3DMode.convert(gt_bboxes, Box3DMode.LIDAR,
-                                          Box3DMode.DEPTH)
-
-        vis = Visualizer(points, save_path='./show.png')
-        vis.add_bboxes(bbox3d=gt_bboxes, bbox_color=(0, 0, 1))
+        file_name = osp.splitext(osp.basename(pts_path))[0]
 
-        vis.show(save_path)
-        del vis
+        if vis_type == 'det':
+            # show 3D bboxes on 3D point clouds
+            show_det_data(
+                idx, dataset, args.output_dir, file_name, show=args.online)
+            if multi_modality:
+                # project 3D bboxes to 2D image
+                show_proj_bbox_img(
+                    idx, dataset, args.output_dir, file_name, show=args.online)
+        elif vis_type == 'seg':
+            # show 3D segmentation mask on 3D point clouds
+            show_seg_data(
+                idx, dataset, args.output_dir, file_name, show=args.online)
 
 
 if __name__ == '__main__':