def __init__(self, root, split="train", pass_name="clean", camera="left", transforms=None):
        super().__init__(root=root, transforms=transforms)

        verify_str_arg(split, "split", valid_values=("train", "test"))
        split = split.upper()

        verify_str_arg(pass_name, "pass_name", valid_values=("clean", "final", "both"))
        passes = {
            "clean": ["frames_cleanpass"],
            "final": ["frames_finalpass"],
            "both": ["frames_cleanpass", "frames_finalpass"],
        }[pass_name]

        verify_str_arg(camera, "camera", valid_values=("left", "right", "both"))
        cameras = ["left", "right"] if camera == "both" else [camera]

        root = Path(root) / "FlyingThings3D"

        directions = ("into_future", "into_past")
        for pass_name, camera, direction in itertools.product(passes, cameras, directions):
            image_dirs = sorted(glob(str(root / pass_name / split / "*/*")))
            image_dirs = sorted(Path(image_dir) / camera for image_dir in image_dirs)

            flow_dirs = sorted(glob(str(root / "optical_flow" / split / "*/*")))
            flow_dirs = sorted(Path(flow_dir) / direction / camera for flow_dir in flow_dirs)

            if not image_dirs or not flow_dirs:
                raise FileNotFoundError(
                    "Could not find the FlyingThings3D flow images. "
                    "Please make sure the directory structure is correct."
                )

            for image_dir, flow_dir in zip(image_dirs, flow_dirs):
                images = sorted(glob(str(image_dir / "*.png")))
                flows = sorted(glob(str(flow_dir / "*.pfm")))
                for i in range(len(flows) - 1):
                    if direction == "into_future":
                        self._image_list += [[images[i], images[i + 1]]]
                        self._flow_list += [flows[i]]
                    elif direction == "into_past":
                        self._image_list += [[images[i + 1], images[i]]]
                        self._flow_list += [flows[i + 1]]