Source code for Finding Action Tubes, created by Georgia Gkioxari at UC Berkeley.

1. Requirements
2. Usage
3. Instructions
4. Downloads

You need Caffe. Please refer to Caffe installation instructions

The pipeline consists of multiple steps. For simplicity, we break them down to independent procedures.

1. In startup.m, add the paths and resolve the dependencies

2. Selective search boxes need to be stored in the following format
   /ss_dir/motion/action/video/0000f.mat
   Video frames need to be stored in the following format
   /img_dir/action/video/0000f.png

3. Optical flow computation

    compute_OF/compute_flow.m	for a pair of images computes flow as described in the paper.	im1, im2: input images	optical flow images need to be stored in the format `/flow_dir/action/video/0000f.png` 

4. Motion saliency

    motion_saliency/get_motion_salient_boxes.m	for each frame, prunes boxes (e.g. from Selective Search) based the optical flow signal within each box. annot: set of videos and actions, jhmdb_annot.mat ss_dir: directory containing the boxes flow_dir: directory containing the optical flow images (as computed by A.) 

5. Extract fc7 features

    extract_features/rcnn_cache_fc7_features_jhmdb.m	extracts fc7 features type: 'spatial' or 'motion' net_def_file: prototxts, `models/jhmdb/extract_fc7.prototxt`. Same for any type net_file: models, use pretrained models for JHMDB as provided in the project page output_dir: cache directory, the features are cached in output_dir/type/action/video/frame.mat 

6. Train SVM models

    train_svm/train_jhmdb.m	trains SVM models, one for each action	annot: ground truth information and boxes (after pruning), jhmdb_motion_sal_annot.mat	feat_dir: directory with cached features	save_dir: cache directory 

7. Action Tubes

    train_svm/compute_tubes.m	scores and links detections to create the final action tubes	annot: source of boxes, `jhmdb_motion_sal_annot.mat`	rcnn_model: the models as computed by train_jhmdb.m 

8. Precomputed tubes

    test_tubes/	tubes for all three splits of J-HMDB and UCF sports test_tubes/UCFsports_benchmark/	AUC and ROC numbers for UCFSports and plots (see ipython notebook) 

9. Evaluate/ROC curves

    evaluate/get_ROC_curve_JHMDB.m	computes ROC and AUC for JHMDB	annot: ground truth annotation (annot_jhdmb.mat)	tubes: tubes on the test set	actions: list of actions	iou_thresh: threshold for intersection over union	draw: true to draw the curves (For UCF sports the same function was used with some small adjustments regarding the format of the data) 

To train action tubes from scratch, you need to train two networks.

Training spatial-CNN and motion-CNN

1. Compute the optical flow as in A. 2. Create `window_train(val).txt` with the window data (similar to R-CNN detection) 3. Use Caffe to train (train prototxt is given in `models/jhmdb/train.prototxt`), and initialize with the proper model 4. In the case of motion-CNN, you need to make two changes in `window_data_layer.cpp`	a. The image mean is for all channels 128 (instead of the image mean provided)	b. During training, when flipping of the input image occurs the flow in x needs to also change sign 

Download pretrained models from the project's webpage