# Apply Net

`apply_net` is a tool to print or visualize DensePose results on a set of images.
It has two modes: `dump` to save DensePose model results to a pickle file
and `show` to visualize them on images.

## Dump Mode

The general command form is:
```bash
python apply_net.py dump [-h] [-v] [--output <dump_file>] <config> <model> <input>
```

There are three mandatory arguments:
 - `<config>`, configuration file for a given model;
 - `<model>`, model file with trained parameters
 - `<input>`, input image file name, pattern or folder

One can additionally provide `--output` argument to define the output file name,
which defaults to `output.pkl`.


Examples:

1. Dump results of a DensePose model with ResNet-50 FPN backbone for images
   in a folder `images` to file `dump.pkl`:
```bash
python apply_net.py dump configs/densepose_rcnn_R_50_FPN_s1x.yaml DensePose_ResNet50_FPN_s1x-e2e.pkl images --output dump.pkl -v
```

2. Dump results of a DensePose model with ResNet-50 FPN backbone for images
   with file name matching a pattern `image*.jpg` to file `results.pkl`:
```bash
python apply_net.py dump configs/densepose_rcnn_R_50_FPN_s1x.yaml DensePose_ResNet50_FPN_s1x-e2e.pkl "image*.jpg" --output results.pkl -v
```

If you want to load the pickle file generated by the above command:
```
# make sure DensePose is in your PYTHONPATH, or use the following line to add it:
sys.path.append("/your_detectron2_path/detectron2_repo/projects/DensePose/")

f = open('/your_result_path/results.pkl', 'rb')
data = pickle.load(f)
```

The file `results.pkl` contains the list of results per image, for each image the result is a dictionary:
```
data: [{'file_name': '/your_path/image1.jpg',
        'scores': tensor([0.9884]),
        'pred_boxes_XYXY': tensor([[ 69.6114,   0.0000, 706.9797, 706.0000]]),
        'pred_densepose': <densepose.structures.DensePoseResult object at 0x7f791b312470>},
       {'file_name': '/your_path/image2.jpg',
        'scores': tensor([0.9999, 0.5373, 0.3991]),
        'pred_boxes_XYXY': tensor([[ 59.5734,   7.7535, 579.9311, 932.3619],
                                   [612.9418, 686.1254, 612.9999, 704.6053],
                                   [164.5081, 407.4034, 598.3944, 920.4266]]),
        'pred_densepose': <densepose.structures.DensePoseResult object at 0x7f7071229be0>}]
```

We can use the following code, to parse the outputs of the first
detected instance on the first image.
```
from densepose.data.structures import DensePoseResult
img_id, instance_id = 0, 0  # Look at the first image and the first detected instance
bbox_xyxy = data[img_id]['pred_boxes_XYXY'][instance_id]
result_encoded = data[img_id]['pred_densepose'].results[instance_id]
iuv_arr = DensePoseResult.decode_png_data(*result_encoded)
```
The array `bbox_xyxy` contains (x0, y0, x1, y1) of the bounding box.

The shape of `iuv_arr` is `[3, H, W]`, where (H, W) is the shape of the bounding box.
- `iuv_arr[0,:,:]`: The patch index of image points, indicating which of the 24 surface patches the point is on.
- `iuv_arr[1,:,:]`: The U-coordinate value of image points.
- `iuv_arr[2,:,:]`: The V-coordinate value of image points.


## Visualization Mode

The general command form is:
```bash
python apply_net.py show [-h] [-v] [--min_score <score>] [--nms_thresh <threshold>] [--output <image_file>] <config> <model> <input> <visualizations>
```

There are four mandatory arguments:
 - `<config>`, configuration file for a given model;
 - `<model>`, model file with trained parameters
 - `<input>`, input image file name, pattern or folder
 - `<visualizations>`, visualizations specifier; currently available visualizations are:
   * `bbox` - bounding boxes of detected persons;
   * `dp_segm` - segmentation masks for detected persons;
   * `dp_u` - each body part is colored according to the estimated values of the
     U coordinate in part parameterization;
   * `dp_v` - each body part is colored according to the estimated values of the
     V coordinate in part parameterization;
   * `dp_contour` - plots contours with color-coded U and V coordinates


One can additionally provide the following optional arguments:
 - `--min_score` to only show detections with sufficient scores that are not lower than provided value
 - `--nms_thresh` to additionally apply non-maximum suppression to detections at a given threshold
 - `--output` to define visualization file name template, which defaults to `output.png`.
   To distinguish output file names for different images, the tool appends 1-based entry index,
   e.g. output.0001.png, output.0002.png, etc...


The following examples show how to output results of a DensePose model
with ResNet-50 FPN backbone using different visualizations for image `image.jpg`:

1. Show bounding box and segmentation:
```bash
python apply_net.py show configs/densepose_rcnn_R_50_FPN_s1x.yaml DensePose_ResNet50_FPN_s1x-e2e.pkl image.jpg bbox,dp_segm -v
```
![Bounding Box + Segmentation Visualization](images/res_bbox_dp_segm.jpg)

2. Show bounding box and estimated U coordinates for body parts:
```bash
python apply_net.py show configs/densepose_rcnn_R_50_FPN_s1x.yaml DensePose_ResNet50_FPN_s1x-e2e.pkl image.jpg bbox,dp_u -v
```
![Bounding Box + U Coordinate Visualization](images/res_bbox_dp_u.jpg)

3. Show bounding box and estimated V coordinates for body parts:
```bash
python apply_net.py show configs/densepose_rcnn_R_50_FPN_s1x.yaml DensePose_ResNet50_FPN_s1x-e2e.pkl image.jpg bbox,dp_v -v
```
![Bounding Box + V Coordinate Visualization](images/res_bbox_dp_v.jpg)

4. Show bounding box and estimated U and V coordinates via contour plots:
```bash
python apply_net.py show configs/densepose_rcnn_R_50_FPN_s1x.yaml DensePose_ResNet50_FPN_s1x-e2e.pkl image.jpg dp_contour,bbox -v
```
![Bounding Box + Contour Visualization](images/res_bbox_dp_contour.jpg)