How to prepare dataset?

COCO
MPII
Training for other dataset

COCO

Preperation for COCO dataset

We provide a one-click script to automatically complete the download and preparation of the COCO2017 dataset. Please refer to COCO Download.

Description for COCO dataset（Keypoint):

In COCO, the indexes and corresponding keypoint name are:

COCO keypoint indexes:
        0: 'nose',
        1: 'left_eye',
        2: 'right_eye',
        3: 'left_ear',
        4: 'right_ear',
        5: 'left_shoulder',
        6: 'right_shoulder',
        7: 'left_elbow',
        8: 'right_elbow',
        9: 'left_wrist',
        10: 'right_wrist',
        11: 'left_hip',
        12: 'right_hip',
        13: 'left_knee',
        14: 'right_knee',
        15: 'left_ankle',
        16: 'right_ankle'

Being different from detection task, the annotation files for keyPoint task are person_keypoints_train2017.json and person_keypoints_val2017.json. In these two json files, the terms info、licenses and images are same with detection task. However, the annotations and categories are different.

In categories, in addition to the category, there are also the names of the keypoints and the connectivity among them.

In annotations, the ID and image of each instance are annotated, as well as segmentation information and keypoint information. Among them, terms related to the keypoints are:

keypoints: [x1,y1,v1 ...], which is a List with length 17*3=51. Each combination represents the coordinates and visibility of one keypoint. v=0, x=0, y=0 indicates this keypoint is not visible and unlabeled. v=1 indicates this keypoint is labeled but not visible. v=2 indicates this keypoint is labeled and visible.
bbox: [x1,y1,w,h], the bounding box of this instance.
num_keypoints: the number of labeled keypoints of this instance.

MPII

Preperation for MPII dataset

Please download MPII dataset images and corresponding annotation files from MPII Human Pose Dataset, and save them to dataset/mpii. You can use mpii_annotations, which are already converted to .json. The directory structure will be shown as:

mpii
|── annotations
|   |── mpii_gt_val.mat
|   |── mpii_test.json
|   |── mpii_train.json
|   |── mpii_trainval.json
|   `── mpii_val.json
`── images
    |── 000001163.jpg
    |── 000003072.jpg

Description for MPII dataset

In MPII, the indexes and corresponding keypoint name are:

MPII keypoint indexes:
        0: 'right_ankle',
        1: 'right_knee',
        2: 'right_hip',
        3: 'left_hip',
        4: 'left_knee',
        5: 'left_ankle',
        6: 'pelvis',
        7: 'thorax',
        8: 'upper_neck',
        9: 'head_top',
        10: 'right_wrist',
        11: 'right_elbow',
        12: 'right_shoulder',
        13: 'left_shoulder',
        14: 'left_elbow',
        15: 'left_wrist',

The following example takes a parsed annotation information to illustrate the content of the annotation, each annotation information represents a person instance:

{
    'joints_vis': [0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    'gt_joints': [
        [-1.0, -1.0],
        [-1.0, -1.0],
        [-1.0, -1.0],
        [-1.0, -1.0],
        [-1.0, -1.0],
        [-1.0, -1.0],
        [-1.0, -1.0],
        [1232.0, 288.0],
        [1236.1271, 311.7755],
        [1181.8729, -0.77553],
        [692.0, 464.0],
        [902.0, 417.0],
        [1059.0, 247.0],
        [1405.0, 329.0],
        [1498.0, 613.0],
        [1303.0, 562.0]
    ],
    'image': '077096718.jpg',
    'scale': 9.516749,
    'center': [1257.0, 297.0]
}

joints_vis: indicates whether the 16 keypoints are labeled respectively, if it is 0, the corresponding coordinate will be [-1.0, -1.0].
joints: the coordinates of 16 keypoints.
image: image file which this instance belongs to.
center: the coordinate of person instance center, which is used to locate instance in the image.
scale: scale of the instance, corresponding to 200px.

Training for other dataset

Here, we take AI Challenger dataset as example, to show how to align other datasets to COCO and add them into training of keypoint models.

In AI Challenger, the indexes and corresponding keypoint name are:

AI Challenger Description:
        0: 'Right Shoulder',
        1: 'Right Elbow',
        2: 'Right Wrist',
        3: 'Left Shoulder',
        4: 'Left Elbow',
        5: 'Left Wrist',
        6: 'Right Hip',
        7: 'Right Knee',
        8: 'Right Ankle',
        9: 'Left Hip',
        10: 'Left Knee',
        11: 'Left Ankle',
        12: 'Head top',
        13: 'Neck'

Align the indexes of the AI Challenger keypoint to be consistent with COCO. For example, the index of Right Shoulder should be adjusted from 0 to 13.
Unify the flags whether the keypoint is labeled/visible. For example, labeled and visible in AI Challenger needs to be adjusted from 1 to 2.
In this proprocess, we discard the unique keypoints in this dataset (like Neck). For keypoints not in this dataset but in COCO (like left_eye), we set v=0, x=0, y=0 to indicate these keypoints are not labeled.
To avoid the problem of ID duplication in different datasets, the image_id and annotation id need to be rearranged.
Rewrite the image path file_name, to make sure images can be accessed correctly.

We also provide an annotation file combining COCO trainset and AI Challenger trainset.

SUM010
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