def METHOD_NAME(img_data, depth_data, NDVI_data=None):
    """Combine the various source of imagery into a multi-channel image
    """
    if NDVI_data is None:
        img = np.zeros([1, img_data.shape[0], img_data.shape[1], 4], dtype=np.float32)
    else:
        img = np.zeros([1, img_data.shape[0], img_data.shape[1], 5], dtype=np.float32)
    float_img = (np.float32(img_data.copy())/255.0-0.5)*2.0
    float_depth = (np.float32(depth_data.copy())/255.0 - 0.5)*2.0
    img[0, :, :, :3] = float_img
    img[0, :, :, 3] = float_depth
    if NDVI_data is not None:
        float_NDVI = (np.float32(NDVI_data.copy())/255.0-0.5)*2.0
        img[0, :, :, 4] = float_NDVI
    return img