lbw_detector.py

from ultralytics import YOLO
import cv2
import numpy as np
import os

# Load YOLO model (custom-trained or pretrained with compatible classes)
model = YOLO("yolov8n.pt")  # Replace with "lbw_yolov8.pt" if custom-trained

# Target class IDs — update based on your custom model class mapping
CLASS_NAMES = {
    0: "ball",
    1: "bat",
    2: "pad",
    3: "stump",
    4: "player"
}

def detect_lbw_event(frames):
    """
    Detects ball, bat, stump, and pad in each frame.
    Identifies impact and prepares coordinates for trajectory modeling.

    Returns:
        dict: {
            "ball_positions": [x, y] list per frame,
            "impact_frame": int,
            "impact_type": str,
            "objects_per_frame": [
                {"ball": (x, y), "pad": (x, y), ...}
            ]
        }
    """
    ball_positions = []
    impact_frame = -1
    impact_type = None
    objects_per_frame = []

    for idx, frame in enumerate(frames):
        results = model(frame)[0]
        frame_objects = {}

        for det in results.boxes.data:
            x1, y1, x2, y2, conf, cls = det.cpu().numpy()
            class_id = int(cls)
            class_name = CLASS_NAMES.get(class_id, "unknown")
            center_x = int((x1 + x2) / 2)
            center_y = int((y1 + y2) / 2)
            frame_objects[class_name] = (center_x, center_y)

            if class_name == "ball":
                ball_positions.append((idx, center_x, center_y))

        objects_per_frame.append(frame_objects)

        # Basic impact logic: ball overlaps pad or bat
        if "ball" in frame_objects and ("pad" in frame_objects or "bat" in frame_objects):
            bx, by = frame_objects["ball"]
            if "pad" in frame_objects:
                px, py = frame_objects["pad"]
                if abs(bx - px) < 30 and abs(by - py) < 30:
                    impact_frame = idx
                    impact_type = "pad"
                    break
            if "bat" in frame_objects:
                tx, ty = frame_objects["bat"]
                if abs(bx - tx) < 30 and abs(by - ty) < 30:
                    impact_frame = idx
                    impact_type = "bat"
                    break

    return {
        "ball_positions": ball_positions,
        "impact_frame": impact_frame,
        "impact_type": impact_type,
        "objects_per_frame": objects_per_frame
    }