grounded_sam2_tracking_demo.py

import os
import cv2
import torch
import numpy as np
import supervision as sv
from PIL import Image
from sam2.build_sam import build_sam2_video_predictor, build_sam2
from sam2.sam2_image_predictor import SAM2ImagePredictor
from transformers import AutoProcessor, AutoModelForZeroShotObjectDetection 
from utils.track_utils import sample_points_from_masks
from utils.video_utils import create_video_from_images


"""
Step 1: Environment settings and model initialization
"""
# use bfloat16 for the entire notebook
torch.autocast(device_type="cuda", dtype=torch.bfloat16).__enter__()

if torch.cuda.get_device_properties(0).major >= 8:
    # turn on tfloat32 for Ampere GPUs (https://pytorch.org/docs/stable/notes/cuda.html#tensorfloat-32-tf32-on-ampere-devices)
    torch.backends.cuda.matmul.allow_tf32 = True
    torch.backends.cudnn.allow_tf32 = True

# init sam image predictor and video predictor model
sam2_checkpoint = "./checkpoints/sam2.1_hiera_large.pt"
model_cfg = "configs/sam2.1/sam2.1_hiera_l.yaml"

video_predictor = build_sam2_video_predictor(model_cfg, sam2_checkpoint)
sam2_image_model = build_sam2(model_cfg, sam2_checkpoint)
image_predictor = SAM2ImagePredictor(sam2_image_model)


# init grounding dino model from huggingface
model_id = "IDEA-Research/grounding-dino-tiny"
device = "cuda" if torch.cuda.is_available() else "cpu"
processor = AutoProcessor.from_pretrained(model_id)
grounding_model = AutoModelForZeroShotObjectDetection.from_pretrained(model_id).to(device)


# setup the input image and text prompt for SAM 2 and Grounding DINO
# VERY important: text queries need to be lowercased + end with a dot
text = "car."

# `video_dir` a directory of JPEG frames with filenames like `<frame_index>.jpg`  

video_dir = "notebooks/videos/car"

# scan all the JPEG frame names in this directory
frame_names = [
    p for p in os.listdir(video_dir)
    if os.path.splitext(p)[-1] in [".jpg", ".jpeg", ".JPG", ".JPEG"]
]
frame_names.sort(key=lambda p: int(os.path.splitext(p)[0]))

# init video predictor state
inference_state = video_predictor.init_state(video_path=video_dir)

ann_frame_idx = 0  # the frame index we interact with
ann_obj_id = 1  # give a unique id to each object we interact with (it can be any integers)


"""
Step 2: Prompt Grounding DINO and SAM image predictor to get the box and mask for specific frame
"""

# prompt grounding dino to get the box coordinates on specific frame
img_path = os.path.join(video_dir, frame_names[ann_frame_idx])
image = Image.open(img_path)

# run Grounding DINO on the image
inputs = processor(images=image, text=text, return_tensors="pt").to(device)
with torch.no_grad():
    outputs = grounding_model(**inputs)

results = processor.post_process_grounded_object_detection(
    outputs,
    inputs.input_ids,
    box_threshold=0.25,
    text_threshold=0.3,
    target_sizes=[image.size[::-1]]
)

# prompt SAM image predictor to get the mask for the object
image_predictor.set_image(np.array(image.convert("RGB")))

# process the detection results
input_boxes = results[0]["boxes"].cpu().numpy()
OBJECTS = results[0]["labels"]

# prompt SAM 2 image predictor to get the mask for the object
masks, scores, logits = image_predictor.predict(
    point_coords=None,
    point_labels=None,
    box=input_boxes,
    multimask_output=False,
)

# convert the mask shape to (n, H, W)
if masks.ndim == 3:
    masks = masks[None]
    scores = scores[None]
    logits = logits[None]
elif masks.ndim == 4:
    masks = masks.squeeze(1)

"""
Step 3: Register each object's positive points to video predictor with seperate add_new_points call
"""

PROMPT_TYPE_FOR_VIDEO = "box" # or "point"

assert PROMPT_TYPE_FOR_VIDEO in ["point", "box", "mask"], "SAM 2 video predictor only support point/box/mask prompt"

# If you are using point prompts, we uniformly sample positive points based on the mask
if PROMPT_TYPE_FOR_VIDEO == "point":
    # sample the positive points from mask for each objects
    all_sample_points = sample_points_from_masks(masks=masks, num_points=10)

    for object_id, (label, points) in enumerate(zip(OBJECTS, all_sample_points), start=1):
        labels = np.ones((points.shape[0]), dtype=np.int32)
        _, out_obj_ids, out_mask_logits = video_predictor.add_new_points_or_box(
            inference_state=inference_state,
            frame_idx=ann_frame_idx,
            obj_id=object_id,
            points=points,
            labels=labels,
        )
# Using box prompt
elif PROMPT_TYPE_FOR_VIDEO == "box":
    for object_id, (label, box) in enumerate(zip(OBJECTS, input_boxes), start=1):
        _, out_obj_ids, out_mask_logits = video_predictor.add_new_points_or_box(
            inference_state=inference_state,
            frame_idx=ann_frame_idx,
            obj_id=object_id,
            box=box,
        )
# Using mask prompt is a more straightforward way
elif PROMPT_TYPE_FOR_VIDEO == "mask":
    for object_id, (label, mask) in enumerate(zip(OBJECTS, masks), start=1):
        labels = np.ones((1), dtype=np.int32)
        _, out_obj_ids, out_mask_logits = video_predictor.add_new_mask(
            inference_state=inference_state,
            frame_idx=ann_frame_idx,
            obj_id=object_id,
            mask=mask
        )
else:
    raise NotImplementedError("SAM 2 video predictor only support point/box/mask prompts")


"""
Step 4: Propagate the video predictor to get the segmentation results for each frame
"""
video_segments = {}  # video_segments contains the per-frame segmentation results
for out_frame_idx, out_obj_ids, out_mask_logits in video_predictor.propagate_in_video(inference_state):
    video_segments[out_frame_idx] = {
        out_obj_id: (out_mask_logits[i] > 0.0).cpu().numpy()
        for i, out_obj_id in enumerate(out_obj_ids)
    }

"""
Step 5: Visualize the segment results across the video and save them
"""

save_dir = "./tracking_results"

if not os.path.exists(save_dir):
    os.makedirs(save_dir)

ID_TO_OBJECTS = {i: obj for i, obj in enumerate(OBJECTS, start=1)}
for frame_idx, segments in video_segments.items():
    img = cv2.imread(os.path.join(video_dir, frame_names[frame_idx]))
    
    object_ids = list(segments.keys())
    masks = list(segments.values())
    masks = np.concatenate(masks, axis=0)
    
    detections = sv.Detections(
        xyxy=sv.mask_to_xyxy(masks),  # (n, 4)
        mask=masks, # (n, h, w)
        class_id=np.array(object_ids, dtype=np.int32),
    )
    box_annotator = sv.BoxAnnotator()
    annotated_frame = box_annotator.annotate(scene=img.copy(), detections=detections)
    label_annotator = sv.LabelAnnotator()
    annotated_frame = label_annotator.annotate(annotated_frame, detections=detections, labels=[ID_TO_OBJECTS[i] for i in object_ids])
    mask_annotator = sv.MaskAnnotator()
    annotated_frame = mask_annotator.annotate(scene=annotated_frame, detections=detections)
    cv2.imwrite(os.path.join(save_dir, f"annotated_frame_{frame_idx:05d}.jpg"), annotated_frame)


"""
Step 6: Convert the annotated frames to video
"""

output_video_path = "./children_tracking_demo_video.mp4"
create_video_from_images(save_dir, output_video_path)