def get_warp_matrix(theta, size_input, size_dst, size_target):
    """This code is based on
        https://github.com/open-mmlab/mmpose/blob/master/mmpose/core/post_processing/post_transforms.py
        Calculate the transformation matrix under the constraint of unbiased.
    Paper ref: Huang et al. The Devil is in the Details: Delving into Unbiased
    Data Processing for Human Pose Estimation (CVPR 2020).
    Args:
        theta (float): Rotation angle in degrees.
        size_input (np.ndarray): Size of input image [w, h].
        size_dst (np.ndarray): Size of output image [w, h].
        size_target (np.ndarray): Size of ROI in input plane [w, h].
    Returns:
        matrix (np.ndarray): A matrix for transformation.
    """
    theta = np.deg2rad(theta)
    matrix = np.zeros((2, 3), dtype=np.float32)
    scale_x = size_dst[0] / size_target[0]
    scale_y = size_dst[1] / size_target[1]
    matrix[0, 0] = np.cos(theta) * scale_x
    matrix[0, 1] = -np.sin(theta) * scale_x
    matrix[0, 2] = scale_x * (
        -0.5 * size_input[0] * np.cos(theta) + 0.5 * size_input[1] *
        np.sin(theta) + 0.5 * size_target[0])
    matrix[1, 0] = np.sin(theta) * scale_y
    matrix[1, 1] = np.cos(theta) * scale_y
    matrix[1, 2] = scale_y * (
        -0.5 * size_input[0] * np.sin(theta) - 0.5 * size_input[1] *
        np.cos(theta) + 0.5 * size_target[1])
    return matrix
This code is based on
        https://github.com/open-mmlab/mmpose/blob/master/mmpose/core/post_processing/post_transforms.py
        Calculate the transformation matrix under the constraint of unbiased.
    Paper ref: Huang et al. The Devil is in the Details: Delving into Unbiased
    Data Processing for Human Pose Estimation (CVPR 2020).
    Args:
        theta (float): Rotation angle in degrees.
        size_input (np.ndarray): Size of input image [w, h].
        size_dst (np.ndarray): Size of output image [w, h].
        size_target (np.ndarray): Size of ROI in input plane [w, h].
    Returns:
        matrix (np.ndarray): A matrix for transformation.
    
deploy/third_engine/demo_onnx_trt/preprocess.py