Learn about Configs¶
MMDetection3D and other OpenMMLab repositories use MMEngine’s config system. It has a modular and inheritance design, which is convenient to conduct various experiments.
Config file content¶
MMDetection3D uses a modular design, all modules with different functions can be configured through the config. Taking PointPillars as an example, we will introduce each field in the config according to different function modules.
Model config¶
In MMDetection3D’s config, we use model to setup detection algorithm components. In addition to neural network components such as voxel_encoder, backbone etc, it also requires data_preprocessor, train_cfg, and test_cfg. data_preprocessor is responsible for processing a batch of data output by dataloader. train_cfg and test_cfg in the model config are training and testing hyperparameters of the components.
model = dict(
type='VoxelNet',
data_preprocessor=dict(
type='Det3DDataPreprocessor',
voxel=True,
voxel_layer=dict(
max_num_points=32,
point_cloud_range=[0, -39.68, -3, 69.12, 39.68, 1],
voxel_size=[0.16, 0.16, 4],
max_voxels=(16000, 40000))),
voxel_encoder=dict(
type='PillarFeatureNet',
in_channels=4,
feat_channels=[64],
with_distance=False,
voxel_size=[0.16, 0.16, 4],
point_cloud_range=[0, -39.68, -3, 69.12, 39.68, 1]),
middle_encoder=dict(
type='PointPillarsScatter', in_channels=64, output_shape=[496, 432]),
backbone=dict(
type='SECOND',
in_channels=64,
layer_nums=[3, 5, 5],
layer_strides=[2, 2, 2],
out_channels=[64, 128, 256]),
neck=dict(
type='SECONDFPN',
in_channels=[64, 128, 256],
upsample_strides=[1, 2, 4],
out_channels=[128, 128, 128]),
bbox_head=dict(
type='Anchor3DHead',
num_classes=3,
in_channels=384,
feat_channels=384,
use_direction_classifier=True,
assign_per_class=True,
anchor_generator=dict(
type='AlignedAnchor3DRangeGenerator',
ranges=[[0, -39.68, -0.6, 69.12, 39.68, -0.6],
[0, -39.68, -0.6, 69.12, 39.68, -0.6],
[0, -39.68, -1.78, 69.12, 39.68, -1.78]],
sizes=[[0.8, 0.6, 1.73], [1.76, 0.6, 1.73], [3.9, 1.6, 1.56]],
rotations=[0, 1.57],
reshape_out=False),
diff_rad_by_sin=True,
bbox_coder=dict(type='DeltaXYZWLHRBBoxCoder'),
loss_cls=dict(
type='mmdet.FocalLoss',
use_sigmoid=True,
gamma=2.0,
alpha=0.25,
loss_weight=1.0),
loss_bbox=dict(
type='mmdet.SmoothL1Loss',
beta=0.1111111111111111,
loss_weight=2.0),
loss_dir=dict(
type='mmdet.CrossEntropyLoss', use_sigmoid=False,
loss_weight=0.2)),
train_cfg=dict(
assigner=[
dict(
type='Max3DIoUAssigner',
iou_calculator=dict(type='BboxOverlapsNearest3D'),
pos_iou_thr=0.5,
neg_iou_thr=0.35,
min_pos_iou=0.35,
ignore_iof_thr=-1),
dict(
type='Max3DIoUAssigner',
iou_calculator=dict(type='BboxOverlapsNearest3D'),
pos_iou_thr=0.5,
neg_iou_thr=0.35,
min_pos_iou=0.35,
ignore_iof_thr=-1),
dict(
type='Max3DIoUAssigner',
iou_calculator=dict(type='BboxOverlapsNearest3D'),
pos_iou_thr=0.6,
neg_iou_thr=0.45,
min_pos_iou=0.45,
ignore_iof_thr=-1)
],
allowed_border=0,
pos_weight=-1,
debug=False),
test_cfg=dict(
use_rotate_nms=True,
nms_across_levels=False,
nms_thr=0.01,
score_thr=0.1,
min_bbox_size=0,
nms_pre=100,
max_num=50))
Dataset and evaluator config¶
Dataloaders are required for the training, validation, and testing of the runner. Dataset and data pipeline need to be set to build the dataloader. Due to the complexity of this part, we use intermediate variables to simplify the writing of dataloader configs.
dataset_type = 'KittiDataset'
data_root = 'data/kitti/'
class_names = ['Pedestrian', 'Cyclist', 'Car']
point_cloud_range = [0, -39.68, -3, 69.12, 39.68, 1]
input_modality = dict(use_lidar=True, use_camera=False)
metainfo = dict(classes=class_names)
db_sampler = dict(
data_root=data_root,
info_path=data_root + 'kitti_dbinfos_train.pkl',
rate=1.0,
prepare=dict(
filter_by_difficulty=[-1],
filter_by_min_points=dict(Car=5, Pedestrian=5, Cyclist=5)),
classes=class_names,
sample_groups=dict(Car=15, Pedestrian=15, Cyclist=15),
points_loader=dict(
type='LoadPointsFromFile', coord_type='LIDAR', load_dim=4, use_dim=4))
train_pipeline = [
dict(type='LoadPointsFromFile', coord_type='LIDAR', load_dim=4, use_dim=4),
dict(type='LoadAnnotations3D', with_bbox_3d=True, with_label_3d=True),
dict(type='ObjectSample', db_sampler=db_sampler, use_ground_plane=True),
dict(type='RandomFlip3D', flip_ratio_bev_horizontal=0.5),
dict(
type='GlobalRotScaleTrans',
rot_range=[-0.78539816, 0.78539816],
scale_ratio_range=[0.95, 1.05]),
dict(type='PointsRangeFilter', point_cloud_range=point_cloud_range),
dict(type='ObjectRangeFilter', point_cloud_range=point_cloud_range),
dict(type='PointShuffle'),
dict(
type='Pack3DDetInputs',
keys=['points', 'gt_labels_3d', 'gt_bboxes_3d'])
]
test_pipeline = [
dict(type='LoadPointsFromFile', coord_type='LIDAR', load_dim=4, use_dim=4),
dict(
type='MultiScaleFlipAug3D',
img_scale=(1333, 800),
pts_scale_ratio=1,
flip=False,
transforms=[
dict(
type='GlobalRotScaleTrans',
rot_range=[0, 0],
scale_ratio_range=[1., 1.],
translation_std=[0, 0, 0]),
dict(type='RandomFlip3D'),
dict(
type='PointsRangeFilter', point_cloud_range=point_cloud_range)
]),
dict(type='Pack3DDetInputs', keys=['points'])
]
eval_pipeline = [
dict(type='LoadPointsFromFile', coord_type='LIDAR', load_dim=4, use_dim=4),
dict(type='Pack3DDetInputs', keys=['points'])
]
train_dataloader = dict(
batch_size=6,
num_workers=4,
persistent_workers=True,
sampler=dict(type='DefaultSampler', shuffle=True),
dataset=dict(
type='RepeatDataset',
times=2,
dataset=dict(
type=dataset_type,
data_root=data_root,
ann_file='kitti_infos_train.pkl',
data_prefix=dict(pts='training/velodyne_reduced'),
pipeline=train_pipeline,
modality=input_modality,
test_mode=False,
metainfo=metainfo,
box_type_3d='LiDAR')))
val_dataloader = dict(
batch_size=1,
num_workers=1,
persistent_workers=True,
drop_last=False,
sampler=dict(type='DefaultSampler', shuffle=False),
dataset=dict(
type=dataset_type,
data_root=data_root,
data_prefix=dict(pts='training/velodyne_reduced'),
ann_file='kitti_infos_val.pkl',
pipeline=test_pipeline,
modality=input_modality,
test_mode=True,
metainfo=metainfo,
box_type_3d='LiDAR'))
test_dataloader = dict(
batch_size=1,
num_workers=1,
persistent_workers=True,
drop_last=False,
sampler=dict(type='DefaultSampler', shuffle=False),
dataset=dict(
type=dataset_type,
data_root=data_root,
data_prefix=dict(pts='training/velodyne_reduced'),
ann_file='kitti_infos_val.pkl',
pipeline=test_pipeline,
modality=input_modality,
test_mode=True,
metainfo=metainfo,
box_type_3d='LiDAR'))
Evaluators are used to compute the metrics of the trained model on the validation and testing datasets. The config of evaluators consists of one or a list of metric configs:
val_evaluator = dict(
type='KittiMetric',
ann_file=data_root + 'kitti_infos_val.pkl',
metric='bbox')
test_evaluator = val_evaluator
Since the test dataset has no annotation files, the test_dataloader and test_evaluator config in MMDetection3D are generally equal to the val’s. If you want to save the detection results on the test dataset, you can write the config like this:
# inference on test dataset and
# format the output results for submission.
test_dataloader = dict(
batch_size=1,
num_workers=1,
persistent_workers=True,
drop_last=False,
sampler=dict(type='DefaultSampler', shuffle=False),
dataset=dict(
type=dataset_type,
data_root=data_root,
data_prefix=dict(pts='testing/velodyne_reduced'),
ann_file='kitti_infos_test.pkl',
load_eval_anns=False,
pipeline=test_pipeline,
modality=input_modality,
test_mode=True,
metainfo=metainfo,
box_type_3d='LiDAR'))
test_evaluator = dict(
type='KittiMetric',
ann_file=data_root + 'kitti_infos_test.pkl',
metric='bbox',
format_only=True,
submission_prefix='results/kitti-3class/kitti_results')
Training and testing config¶
MMEngine’s runner uses Loop to control the training, validation, and testing processes. Users can set the maximum training epochs and validation intervals with these fields:
train_cfg = dict(
type='EpochBasedTrainLoop',
max_epochs=80,
val_interval=2)
val_cfg = dict(type='ValLoop')
test_cfg = dict(type='TestLoop')
Optimization config¶
optim_wrapper is the field to configure optimization-related settings. The optimizer wrapper not only provides the functions of the optimizer, but also supports functions such as gradient clipping, mixed precision training, etc. Find more in optimizer wrapper tutorial.
optim_wrapper = dict( # Optimizer wrapper config
type='OptimWrapper', # Optimizer wrapper type, switch to AmpOptimWrapper to enable mixed precision training.
optimizer=dict( # Optimizer config. Support all kinds of optimizers in PyTorch. Refer to https://pytorch.org/docs/stable/optim.html#algorithms
type='AdamW', lr=0.001, betas=(0.95, 0.99), weight_decay=0.01),
clip_grad=dict(max_norm=35, norm_type=2)) # Gradient clip option. Set None to disable gradient clip. Find usage in https://mmengine.readthedocs.io/en/latest/tutorials/optim_wrapper.html
param_scheduler is a field that configures methods of adjusting optimization hyperparameters such as learning rate and momentum. Users can combine multiple schedulers to create a desired parameter adjustment strategy. Find more in parameter scheduler tutorial and parameter scheduler API documents.
param_scheduler = [
dict(
type='CosineAnnealingLR',
T_max=32,
eta_min=0.01,
begin=0,
end=32,
by_epoch=True,
convert_to_iter_based=True),
dict(
type='CosineAnnealingLR',
T_max=48,
eta_min=1.0000000000000001e-07,
begin=32,
end=80,
by_epoch=True,
convert_to_iter_based=True),
dict(
type='CosineAnnealingMomentum',
T_max=32,
eta_min=0.8947368421052632,
begin=0,
end=32,
by_epoch=True,
convert_to_iter_based=True),
dict(
type='CosineAnnealingMomentum',
T_max=48,
eta_min=1,
begin=32,
end=80,
by_epoch=True,
convert_to_iter_based=True),
]
Hook config¶
Users can attach Hooks to training, validation, and testing loops to insert some operations during running. There are two different hook fields, one is default_hooks and the other is custom_hooks.
default_hooks is a dict of hook configs, and they are the hooks must be required at the runtime. They have default priority which should not be modified. If not set, runner will use the default values. To disable a default hook, users can set its config to None.
default_hooks = dict(
timer=dict(type='IterTimerHook'),
logger=dict(type='LoggerHook', interval=50),
param_scheduler=dict(type='ParamSchedulerHook'),
checkpoint=dict(type='CheckpointHook', interval=-1),
sampler_seed=dict(type='DistSamplerSeedHook'),
visualization=dict(type='Det3DVisualizationHook'))
custom_hooks is a list of all other hook configs. Users can develop their own hooks and insert them in this field.
custom_hooks = []
Runtime config¶
default_scope = 'mmdet3d' # The default registry scope to find modules. Refer to https://mmengine.readthedocs.io/en/latest/advanced_tutorials/registry.html
env_cfg = dict(
cudnn_benchmark=False, # Whether to enable cudnn benchmark
mp_cfg=dict( # Multi-processing config
mp_start_method='fork', # Use fork to start multi-processing threads. 'fork' usually faster than 'spawn' but maybe unsafe. See discussion in https://github.com/pytorch/pytorch/issues/1355
opencv_num_threads=0), # Disable opencv multi-threads to avoid system being overloaded
dist_cfg=dict(backend='nccl')) # Distribution configs
vis_backends = [dict(type='LocalVisBackend')] # Visualization backends. Refer to https://mmengine.readthedocs.io/en/latest/advanced_tutorials/visualization.html
visualizer = dict(
type='Det3DLocalVisualizer', vis_backends=vis_backends, name='visualizer')
log_processor = dict(
type='LogProcessor', # Log processor to process runtime logs
window_size=50, # Smooth interval of log values
by_epoch=True) # Whether to format logs with epoch type. Should be consistent with the train loop's type.
log_level = 'INFO' # The level of logging.
load_from = None # Load model checkpoint as a pre-trained model from a given path. This will not resume training.
resume = False # Whether to resume from the checkpoint defined in `load_from`. If `load_from` is None, it will resume the latest checkpoint in the `work_dir`.
Config file inheritance¶
There are 4 basic component types under configs/_base_, dataset, model, schedule, default_runtime.
Many methods could be easily constructed with one of these models like SECOND, PointPillars, PartA2, VoteNet.
The configs that are composed of components from _base_ are called primitive.
For all configs under the same folder, it is recommended to have only one primitive config. All other configs should inherit from the primitive config. In this way, the maximum of inheritance level is 3.
For easy understanding, we recommend contributors to inherit from existing methods.
For example, if some modification is made based on PointPillars, users may first inherit the basic PointPillars structure by specifying _base_ = '../pointpillars/pointpillars_hv_fpn_sbn-all_8xb4-2x_nus-3d.py', then modify the necessary fields in the config files.
If you are building an entirely new method that does not share the structure with any of the existing methods, you may create a folder xxx_rcnn under configs.
Please refer to MMEngine config tutorial for detailed documentation.
By setting the _base_ field, we can set which files the current configuration file inherits from.
When _base_ is a string of a file path, it means inheriting the contents from one config file.
_base_ = './pointpillars_hv_secfpn_8xb6-160e_kitti-3d-3class.py'
When _base_ is a list of multiple file paths, it means inheriting from multiple files.
_base_ = [
'../_base_/models/pointpillars_hv_secfpn_kitti.py',
'../_base_/datasets/kitti-3d-3class.py',
'../_base_/schedules/cyclic-40e.py', '../_base_/default_runtime.py'
]
If you wish to inspect the config file, you may run python tools/misc/print_config.py /PATH/TO/CONFIG to see the complete config.
Ignore some fields in the base configs¶
Sometimes, you may set _delete_=True to ignore some of the fields in base configs.
You may refer to MMEngine config tutorial for a simple illustration.
In MMDetection3D, for example, to change the neck of PointPillars with the following config:
model = dict(
type='MVXFasterRCNN',
data_preprocessor=dict(voxel_layer=dict(...)),
pts_voxel_encoder=dict(...),
pts_middle_encoder=dict(...),
pts_backbone=dict(...),
pts_neck=dict(
type='FPN',
norm_cfg=dict(type='naiveSyncBN2d', eps=1e-3, momentum=0.01),
act_cfg=dict(type='ReLU'),
in_channels=[64, 128, 256],
out_channels=256,
start_level=0,
num_outs=3),
pts_bbox_head=dict(...))
FPN and SECONDFPN use different keywords to construct:
_base_ = '../_base_/models/pointpillars_hv_fpn_nus.py'
model = dict(
pts_neck=dict(
_delete_=True,
type='SECONDFPN',
norm_cfg=dict(type='naiveSyncBN2d', eps=1e-3, momentum=0.01),
in_channels=[64, 128, 256],
upsample_strides=[1, 2, 4],
out_channels=[128, 128, 128]),
pts_bbox_head=dict(...))
The _delete_=True would replace all old keys in pts_neck field with new keys.
Use intermediate variables in configs¶
Some intermediate variables are used in the configs files, like train_pipeline/test_pipeline in datasets.
It’s worth noting that when modifying intermediate variables in the children configs, user needs to pass the intermediate variables into corresponding fields again.
For example, we would like to use a multi-scale strategy to train and test a PointPillars, train_pipeline/test_pipeline are intermediate variables we would like to modify.
_base_ = './nus-3d.py'
train_pipeline = [
dict(
type='LoadPointsFromFile',
load_dim=5,
use_dim=5,
backend_args=backend_args),
dict(
type='LoadPointsFromMultiSweeps',
sweeps_num=10,
backend_args=backend_args),
dict(type='LoadAnnotations3D', with_bbox_3d=True, with_label_3d=True),
dict(
type='GlobalRotScaleTrans',
rot_range=[-0.3925, 0.3925],
scale_ratio_range=[0.95, 1.05],
translation_std=[0, 0, 0]),
dict(type='RandomFlip3D', flip_ratio_bev_horizontal=0.5),
dict(type='PointsRangeFilter', point_cloud_range=point_cloud_range),
dict(type='ObjectRangeFilter', point_cloud_range=point_cloud_range),
dict(type='ObjectNameFilter', classes=class_names),
dict(type='PointShuffle'),
dict(
type='Pack3DDetInputs',
keys=['points', 'gt_labels_3d', 'gt_bboxes_3d'])
]
test_pipeline = [
dict(
type='LoadPointsFromFile',
load_dim=5,
use_dim=5,
backend_args=backend_args),
dict(
type='LoadPointsFromMultiSweeps',
sweeps_num=10,
backend_args=backend_args),
dict(
type='MultiScaleFlipAug3D',
img_scale=(1333, 800),
pts_scale_ratio=[0.95, 1.0, 1.05],
flip=False,
transforms=[
dict(
type='GlobalRotScaleTrans',
rot_range=[0, 0],
scale_ratio_range=[1., 1.],
translation_std=[0, 0, 0]),
dict(type='RandomFlip3D'),
dict(
type='PointsRangeFilter', point_cloud_range=point_cloud_range)
]),
dict(type='Pack3DDetInputs', keys=['points'])
]
train_dataloader = dict(dataset=dict(pipeline=train_pipeline))
val_dataloader = dict(dataset=dict(pipeline=test_pipeline))
test_dataloader = dict(dataset=dict(pipeline=test_pipeline))
We first define the new train_pipeline/test_pipeline and pass them into dataloader fields.
Reuse variables in _base_ file¶
If the users want to reuse the variables in the base file, they can get a copy of the corresponding variable by using {{_base_.xxx}}. E.g:
_base_ = './pointpillars_hv_secfpn_8xb6-160e_kitti-3d-3class.py'
a = {{_base_.model}} # variable `a` is equal to the `model` defined in `_base_`
Modify config through script arguments¶
When submitting jobs using tools/train.py or tools/test.py, you may specify --cfg-options to in-place modify the config.
Update config keys of dict chains
The config options can be specified following the order of the dict keys in the original config. For example,
--cfg-options model.backbone.norm_eval=Falsechanges the all BN modules in model backbones totrainmode.Update keys inside a list of configs
Some config dicts are composed as a list in your config. For example, the training pipeline
train_dataloader.dataset.pipelineis normally a list e.g.[dict(type='LoadPointsFromFile'), ...]. If you want to change'LoadPointsFromFile'to'LoadPointsFromDict'in the pipeline, you may specify--cfg-options data.train.pipeline.0.type=LoadPointsFromDict.Update values of list/tuple
If the value to be updated is a list or a tuple. For example, the config file normally sets
model.data_preprocessor.mean=[123.675, 116.28, 103.53]. If you want to change the mean values, you may specify--cfg-options model.data_preprocessor.mean="[127,127,127]". Note that the quotation mark"is necessary to support list/tuple data types, and that NO white space is allowed inside the quotation marks in the specified value.
Config Name Style¶
We follow the below style to name config files. Contributors are advised to follow the same style.
{algorithm name}_{model component names [component1]_[component2]_[...]}_{training settings}_{training dataset information}_{testing dataset information}.py
The file name is divided to five parts. All parts and components are connected with _ and words of each part or component should be connected with -.
{algorithm name}: The name of the algorithm. It can be a detector name such aspointpillars,fcos3d, etc.{model component names}: Names of the components used in the algorithm such as voxel_encoder, backbone, neck, etc. For example,second_secfpn_head-dcn-circlenmsmeans using SECOND’s SparseEncoder, SECONDFPN and a detection head with DCN and circle NMS.{training settings}: Information of training settings such as batch size, augmentations, loss trick, scheduler, and epochs/iterations. For example:8xb4-tta-cyclic-20emeans using 8-gpus x 4-samples-per-gpu, test time augmentation, cyclic annealing learning rate, and train 20 epochs. Some abbreviations:{gpu x batch_per_gpu}: GPUs and samples per GPU.bNindicates N batch size per GPU. E.g.4xb4is the short term of 4-GPUs x 4-samples-per-GPU.{schedule}: training schedule, options areschedule-2x,schedule-3x,cyclic-20e, etc.schedule-2xandschedule-3xmean 24 epochs and 36 epochs respectively.cyclic-20emeans 20 epochs respectively.
{training dataset information}: Training dataset names likekitti-3d-3class,nus-3d,s3dis-seg,scannet-seg,waymoD5-3d-car. Here3dmeans dataset used for 3D object detection, andsegmeans dataset used for point cloud segmentation.{testing dataset information}(optional): Testing dataset name for models trained on one dataset but tested on another. If not mentioned, it means the model was trained and tested on the same dataset type.