Object Detection - Quick Start¶
Object detection is the process of identifying and localizing objects in an image and is an important task in computer vision. Follow this tutorial to learn how to use AutoGluon for object detection.
Tip: If you are new to AutoGluon, review Image Prediction - Quick Start first to learn the basics of the AutoGluon API.
Our goal is to detect motorbike in images by YOLOv3 model. A tiny dataset is collected from VOC dataset, which only contains the motorbike category. The model pretrained on the COCO dataset is used to fine-tune our small dataset. With the help of AutoGluon, we are able to try many models with different hyperparameters automatically, and return the best one as our final model.
To start, import ObjectDetector:
from autogluon.vision import ObjectDetector
/var/lib/jenkins/miniconda3/envs/autogluon-tutorial-object-detection-v3/lib/python3.9/site-packages/gluoncv/__init__.py:40: UserWarning: Both mxnet==1.9.1 and torch==1.12.0+cu102 are installed. You might encounter increased GPU memory footprint if both framework are used at the same time.
warnings.warn(f'Both mxnet=={mx.__version__} and torch=={torch.__version__} are installed. '
Tiny_motorbike Dataset¶
We collect a toy dataset for detecting motorbikes in images. From the VOC dataset, images are randomly selected for training, validation, and testing - 120 images for training, 50 images for validation, and 50 for testing. This tiny dataset follows the same format as VOC.
Using the commands below, we can download this dataset, which is only
23M. The name of unzipped folder is called tiny_motorbike. Anyway,
the task dataset helper can perform the download and extraction
automatically, and load the dataset according to the detection formats.
url = 'https://autogluon.s3.amazonaws.com/datasets/tiny_motorbike.zip'
dataset_train = ObjectDetector.Dataset.from_voc(url, splits='trainval')
Downloading /var/lib/jenkins/.gluoncv/archive/tiny_motorbike.zip from https://autogluon.s3.amazonaws.com/datasets/tiny_motorbike.zip...
21273KB [00:00, 38644.71KB/s]
tiny_motorbike/
├── Annotations/
├── ImageSets/
└── JPEGImages/
Fit Models by AutoGluon¶
In this section, we demonstrate how to apply AutoGluon to fit our detection models. We use mobilenet as the backbone for the YOLOv3 model. Two different learning rates are used to fine-tune the network. The best model is the one that obtains the best performance on the validation dataset. You can also try using more networks and hyperparameters to create a larger searching space.
We fit a classifier using AutoGluon as follows. In each experiment
(one trial in our searching space), we train the model for 5 epochs to
avoid bursting our tutorial runtime.
time_limit = 60*30 # at most 0.5 hour
detector = ObjectDetector()
hyperparameters = {'epochs': 5, 'batch_size': 8}
hyperparameter_tune_kwargs={'num_trials': 2}
detector.fit(dataset_train, time_limit=time_limit, hyperparameters=hyperparameters, hyperparameter_tune_kwargs=hyperparameter_tune_kwargs)
=============================================================================
WARNING: ObjectDetector is deprecated as of v0.4.0 and may contain various bugs and issues!
In a future release ObjectDetector may be entirely reworked to use Torch as a backend.
This future change will likely be API breaking.Users should ensure they update their code that depends on ObjectDetector when upgrading to future AutoGluon releases.
For more information, refer to ObjectDetector refactor GitHub issue: https://github.com/awslabs/autogluon/issues/1559
=============================================================================
The number of requested GPUs is greater than the number of available GPUs.Reduce the number to 1
Randomly split train_data into train[159]/validation[11] splits.
Starting HPO experiments
0%| | 0/2 [00:00<?, ?it/s]
modified configs(<old> != <new>): {
root.dataset_root ~/.mxnet/datasets/ != auto
root.valid.batch_size 16 != 8
root.num_workers 4 != 8
root.train.early_stop_max_value 1.0 != inf
root.train.seed 233 != 483
root.train.batch_size 16 != 8
root.train.epochs 20 != 5
root.train.early_stop_patience -1 != 10
root.train.early_stop_baseline 0.0 != -inf
root.ssd.base_network vgg16_atrous != resnet50_v1
root.ssd.data_shape 300 != 512
root.dataset voc_tiny != auto
root.gpus (0, 1, 2, 3) != (0,)
}
Saved config to /var/lib/jenkins/workspace/workspace/autogluon-tutorial-object-detection-v3/docs/_build/eval/tutorials/object_detection/337882c4/.trial_0/config.yaml
Using transfer learning from ssd_512_resnet50_v1_coco, the other network parameters are ignored.
Start training from [Epoch 0]
[Epoch 0] Training cost: 11.749964, CrossEntropy=3.693248, SmoothL1=1.057459
[Epoch 0] Validation:
cow=nan
motorbike=0.7498297157388065
person=0.457537053042671
boat=nan
bicycle=nan
dog=nan
car=nan
bus=nan
chair=nan
pottedplant=nan
mAP=0.6036833843907388
[Epoch 0] Current best map: 0.603683 vs previous 0.000000, saved to /var/lib/jenkins/workspace/workspace/autogluon-tutorial-object-detection-v3/docs/_build/eval/tutorials/object_detection/337882c4/.trial_0/best_checkpoint.pkl
[Epoch 1] Training cost: 7.528499, CrossEntropy=2.714168, SmoothL1=1.205790
[Epoch 1] Validation:
cow=nan
motorbike=0.9116161616161615
person=0.5745920745920747
boat=nan
bicycle=nan
dog=nan
car=nan
bus=nan
chair=nan
pottedplant=nan
mAP=0.7431041181041181
[Epoch 1] Current best map: 0.743104 vs previous 0.603683, saved to /var/lib/jenkins/workspace/workspace/autogluon-tutorial-object-detection-v3/docs/_build/eval/tutorials/object_detection/337882c4/.trial_0/best_checkpoint.pkl
[Epoch 2] Training cost: 7.556069, CrossEntropy=2.473619, SmoothL1=1.099612
[Epoch 2] Validation:
cow=nan
motorbike=0.7774104683195593
person=0.6260330578512396
boat=nan
bicycle=nan
dog=nan
car=nan
bus=nan
chair=nan
pottedplant=nan
mAP=0.7017217630853995
[Epoch 3] Training cost: 7.620344, CrossEntropy=2.426621, SmoothL1=1.102698
[Epoch 3] Validation:
cow=nan
motorbike=0.8367003367003367
person=0.6542346542346542
boat=nan
bicycle=nan
dog=nan
car=nan
bus=nan
chair=nan
pottedplant=nan
mAP=0.7454674954674955
[Epoch 3] Current best map: 0.745467 vs previous 0.743104, saved to /var/lib/jenkins/workspace/workspace/autogluon-tutorial-object-detection-v3/docs/_build/eval/tutorials/object_detection/337882c4/.trial_0/best_checkpoint.pkl
[Epoch 4] Training cost: 7.692455, CrossEntropy=2.423656, SmoothL1=1.115716
[Epoch 4] Validation:
cow=nan
motorbike=0.8181818181818183
person=0.5852487135506003
boat=nan
bicycle=nan
dog=nan
car=nan
bus=nan
chair=nan
pottedplant=nan
mAP=0.7017152658662094
Applying the state from the best checkpoint...
Finished, total runtime is 67.34 s
{ 'best_config': { 'dataset': 'auto',
'dataset_root': 'auto',
'estimator': <class 'gluoncv.auto.estimators.ssd.ssd.SSDEstimator'>,
'gpus': [0],
'horovod': False,
'num_workers': 8,
'resume': '',
'save_interval': 1,
'ssd': { 'amp': False,
'base_network': 'resnet50_v1',
'data_shape': 512,
'filters': None,
'nms_thresh': 0.45,
'nms_topk': 400,
'ratios': ( [1, 2, 0.5],
[1, 2, 0.5, 3, 0.3333333333333333],
[1, 2, 0.5, 3, 0.3333333333333333],
[1, 2, 0.5, 3, 0.3333333333333333],
[1, 2, 0.5],
[1, 2, 0.5]),
'sizes': (30, 60, 111, 162, 213, 264, 315),
'steps': (8, 16, 32, 64, 100, 300),
'syncbn': False,
'transfer': 'ssd_512_resnet50_v1_coco'},
'train': { 'batch_size': 8,
'dali': False,
'early_stop_baseline': -inf,
'early_stop_max_value': inf,
'early_stop_min_delta': 0.001,
'early_stop_patience': 10,
'epochs': 5,
'log_interval': 100,
'lr': 0.001,
'lr_decay': 0.1,
'lr_decay_epoch': (160, 200),
'momentum': 0.9,
'seed': 483,
'start_epoch': 0,
'wd': 0.0005},
'valid': { 'batch_size': 8,
'iou_thresh': 0.5,
'metric': 'voc07',
'val_interval': 1}},
'total_time': 67.33460140228271,
'train_map': 0.7934178386806936,
'valid_map': 0.7454674954674955}
<autogluon.vision.detector.detector.ObjectDetector at 0x7f205f68b6a0>
Note that num_trials=2 above is only used to speed up the tutorial.
In normal practice, it is common to only use time_limit and drop
num_trials. Also note that hyperparameter tuning defaults to random
search.
After fitting, AutoGluon automatically returns the best model among all models in the searching space. From the output, we know the best model is the one trained with the second learning rate. To see how well the returned model performed on test dataset, call detector.evaluate().
dataset_test = ObjectDetector.Dataset.from_voc(url, splits='test')
test_map = detector.evaluate(dataset_test)
print("mAP on test dataset: {}".format(test_map[1][-1]))
tiny_motorbike/
├── Annotations/
├── ImageSets/
└── JPEGImages/
mAP on test dataset: 0.12134800278101077
Below, we randomly select an image from test dataset and show the
predicted class, box and probability over the origin image, stored in
predict_class, predict_rois and predict_score columns,
respectively. You can interpret predict_rois as a dict of (xmin,
ymin, xmax, ymax) proportional to original image size.
image_path = dataset_test.iloc[0]['image']
result = detector.predict(image_path)
print(result)
predict_class predict_score 0 person 0.993079
1 motorbike 0.991182
2 motorbike 0.931126
3 person 0.184655
4 person 0.182142
.. ... ...
67 person 0.040077
68 person 0.039211
69 person 0.038838
70 person 0.038625
71 person 0.038397
predict_rois
0 {'xmin': 0.39837729930877686, 'ymin': 0.298079...
1 {'xmin': 0.31761884689331055, 'ymin': 0.412470...
2 {'xmin': 0.006848023738712072, 'ymin': 0.64291...
3 {'xmin': 0.03011605143547058, 'ymin': 0.0, 'xm...
4 {'xmin': 0.9170039892196655, 'ymin': 0.0, 'xma...
.. ...
67 {'xmin': 0.37754252552986145, 'ymin': 0.377631...
68 {'xmin': 0.763992965221405, 'ymin': 0.00346376...
69 {'xmin': 0.9517209529876709, 'ymin': 0.0644460...
70 {'xmin': 0.42817020416259766, 'ymin': 0.064593...
71 {'xmin': 0.9023417234420776, 'ymin': 0.0, 'xma...
[72 rows x 3 columns]
Prediction with multiple images is permitted:
bulk_result = detector.predict(dataset_test)
print(bulk_result)
predict_class predict_score 0 person 0.993079
1 motorbike 0.991182
2 motorbike 0.931126
3 person 0.184655
4 person 0.182142
... ... ...
4595 person 0.046932
4596 person 0.046826
4597 person 0.046801
4598 person 0.046699
4599 person 0.046650
predict_rois 0 {'xmin': 0.39837729930877686, 'ymin': 0.298079...
1 {'xmin': 0.31761884689331055, 'ymin': 0.412470...
2 {'xmin': 0.006848023738712072, 'ymin': 0.64291...
3 {'xmin': 0.03011605143547058, 'ymin': 0.0, 'xm...
4 {'xmin': 0.9170039892196655, 'ymin': 0.0, 'xma...
... ...
4595 {'xmin': 0.783810019493103, 'ymin': 0.05305084...
4596 {'xmin': 0.6564183235168457, 'ymin': 0.0752390...
4597 {'xmin': 0.801733136177063, 'ymin': 0.07280851...
4598 {'xmin': 0.3997936546802521, 'ymin': 0.0718678...
4599 {'xmin': 0.4224648177623749, 'ymin': 0.0068740...
image
0 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
1 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
2 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
3 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
4 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
... ...
4595 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
4596 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
4597 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
4598 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
4599 /var/lib/jenkins/.gluoncv/datasets/tiny_motorb...
[4600 rows x 4 columns]
We can also save the trained model, and use it later.
savefile = 'detector.ag'
detector.save(savefile)
new_detector = ObjectDetector.load(savefile)
/var/lib/jenkins/miniconda3/envs/autogluon-tutorial-object-detection-v3/lib/python3.9/site-packages/mxnet/gluon/block.py:1784: UserWarning: Cannot decide type for the following arguments. Consider providing them as input:
data: None
input_sym_arg_type = in_param.infer_type()[0]