[Feature] Generate ann_file for flyingchairs (#121)

* [Feature] Generate ann_file for flyingchairs

* del debug code

* add subdit

* dir

* add flow dir

* img info ann info

* lint

tools/prepare_datasets/prepare_flyingchairs.py

@@ -0,0 +1,78 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import argparse
+import json
+import os.path as osp
+
+import mmcv
+import numpy as np
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(
+        description='FlyingChairs dataset preparation')
+    parser.add_argument(
+        '--data-root',
+        type=str,
+        default='data/FlyingChairs_release',
+        help='Directory for dataset.')
+    parser.add_argument(
+        '--split-file',
+        type=str,
+        default='data/FlyingChairs_release/FlyingChairs_train_val.txt',
+        help='File name of '
+        'train-validation split file for FlyingChairs.')
+    args = parser.parse_args()
+
+    return args
+
+
+def main():
+    args = parse_args()
+
+    split = np.loadtxt(args.split_file, dtype=np.int32).tolist()
+    # unpack FlyingChairs directly, will see `data` subdirctory.
+    img1_dir = osp.join(args.data_root, 'data')
+    img2_dir = osp.join(args.data_root, 'data')
+    flow_dir = osp.join(args.data_root, 'data')
+
+    # data in FlyingChairs dataset has specific suffix
+    img1_suffix = '_img1.ppm'
+    img2_suffix = '_img2.ppm'
+    flow_suffix = '_flow.flo'
+
+    img1_filenames = [f for f in mmcv.scandir(img1_dir, suffix=img1_suffix)]
+    img2_filenames = [f for f in mmcv.scandir(img2_dir, suffix=img2_suffix)]
+    flow_filenames = [f for f in mmcv.scandir(flow_dir, suffix=flow_suffix)]
+    img1_filenames.sort()
+    img2_filenames.sort()
+    flow_filenames.sort()
+
+    train_list = []
+    test_list = []
+    train_meta = dict(dataset='FlyingChairs', subset='train')
+    test_meta = dict(dataset='FlyingChairs', subset='test')
+
+    for i, flag in enumerate(split):
+
+        data_info = dict(
+            img1_dir='data',
+            img2_dir='data',
+            flow_dir='data',
+            img_info=dict(
+                filename1=img1_filenames[i], filename2=img2_filenames[i]),
+            ann_info=dict(filename_flow=flow_filenames[i]))
+
+        if flag == 1:
+            train_list.append(data_info)
+        else:
+            test_list.append(data_info)
+
+    with open('FlyingChairs_train.json', 'w') as jsonfile:
+        json.dump({'data_list': train_list, 'metainfo': train_meta}, jsonfile)
+
+    with open('FlyingChairs_test.json', 'w') as jsonfile:
+        json.dump({'data_list': test_list, 'metainfo': test_meta}, jsonfile)
+
+
+if __name__ == '__main__':
+    main()