Derived Cameras Docstrings

MetashapeCameraSet

Bases: PhotogrammetryCameraSet

Source code in geograypher/cameras/derived_cameras.py

class MetashapeCameraSet(PhotogrammetryCameraSet):
    def __init__(
        self,
        camera_file: PATH_TYPE,
        image_folder: PATH_TYPE,
        validate_images: bool = False,
        default_sensor_params: dict = {},
    ):
        """Parse the information about the camera intrinsics and extrinsics

        Args:
            camera_file (PATH_TYPE): Path to metashape .xml export
            image_folder: (PATH_TYPE): Path to image folder root

        Raises:
            ValueError: If camera calibration does not contain the f, cx, and cy params
        """
        # Load the xml file
        # Taken from here https://rowelldionicio.com/parsing-xml-with-python-minidom/
        tree = ET.parse(camera_file)
        root = tree.getroot()
        # first level
        chunk = root.find("chunk")
        # second level
        sensors = chunk.find("sensors")
        # Parse the sensors representation
        sensors_dict = parse_sensors(sensors, default_sensor_dict=default_sensor_params)

        # Set up the lists to populate
        image_filenames = []
        cam_to_world_transforms = []
        sensor_IDs = []

        cameras = chunk[2]
        # Iterate over metashape cameras and fill out required information
        for cam_or_group in cameras:
            if cam_or_group.tag == "group":
                for cam in cam_or_group:
                    update_lists(
                        cam,
                        image_folder,
                        cam_to_world_transforms,
                        image_filenames,
                        sensor_IDs,
                    )
            else:
                # 4x4 transform
                update_lists(
                    cam_or_group,
                    image_folder,
                    cam_to_world_transforms,
                    image_filenames,
                    sensor_IDs,
                )

        # Compute the lat lon using the transforms, because the reference values recorded in the file
        # reflect the EXIF values, not the optimized ones

        # Get the transform from the chunk to the earth-centered, earth-fixed (ECEF) frame
        chunk_to_epsg4327 = parse_transform_metashape(camera_file=camera_file)

        if chunk_to_epsg4327 is not None:
            # Compute the location of each camera in ECEF
            cam_locs_in_epsg4327 = []
            for cam_to_world_transform in cam_to_world_transforms:
                cam_loc_in_chunk = cam_to_world_transform[:, 3:]
                cam_locs_in_epsg4327.append(chunk_to_epsg4327 @ cam_loc_in_chunk)
            cam_locs_in_epsg4327 = np.concatenate(cam_locs_in_epsg4327, axis=1)[:3].T
            # Transform these points into lat-lon-alt
            transformer = pyproj.Transformer.from_crs(
                EARTH_CENTERED_EARTH_FIXED_CRS, LAT_LON_CRS
            )
            lat, lon, _ = transformer.transform(
                xx=cam_locs_in_epsg4327[:, 0],
                yy=cam_locs_in_epsg4327[:, 1],
                zz=cam_locs_in_epsg4327[:, 2],
            )
            lon_lats = list(zip(lon, lat))
        else:
            # TODO consider trying to parse from the xml
            lon_lats = None

        # Actually construct the camera objects using the base class
        super().__init__(
            cam_to_world_transforms=cam_to_world_transforms,
            intrinsic_params_per_sensor_type=sensors_dict,
            image_filenames=image_filenames,
            lon_lats=lon_lats,
            image_folder=image_folder,
            sensor_IDs=sensor_IDs,
            validate_images=validate_images,
            local_to_epsg_4978_transform=chunk_to_epsg4327,
        )

Functions

__init__(camera_file, image_folder, validate_images=False, default_sensor_params={})

Parse the information about the camera intrinsics and extrinsics

Parameters:

Name	Type	Description	Default
camera_file	PATH_TYPE	Path to metashape .xml export	required
image_folder	PATH_TYPE	(PATH_TYPE): Path to image folder root	required

Raises:

Type	Description
ValueError	If camera calibration does not contain the f, cx, and cy params

Source code in geograypher/cameras/derived_cameras.py

def __init__(
    self,
    camera_file: PATH_TYPE,
    image_folder: PATH_TYPE,
    validate_images: bool = False,
    default_sensor_params: dict = {},
):
    """Parse the information about the camera intrinsics and extrinsics

    Args:
        camera_file (PATH_TYPE): Path to metashape .xml export
        image_folder: (PATH_TYPE): Path to image folder root

    Raises:
        ValueError: If camera calibration does not contain the f, cx, and cy params
    """
    # Load the xml file
    # Taken from here https://rowelldionicio.com/parsing-xml-with-python-minidom/
    tree = ET.parse(camera_file)
    root = tree.getroot()
    # first level
    chunk = root.find("chunk")
    # second level
    sensors = chunk.find("sensors")
    # Parse the sensors representation
    sensors_dict = parse_sensors(sensors, default_sensor_dict=default_sensor_params)

    # Set up the lists to populate
    image_filenames = []
    cam_to_world_transforms = []
    sensor_IDs = []

    cameras = chunk[2]
    # Iterate over metashape cameras and fill out required information
    for cam_or_group in cameras:
        if cam_or_group.tag == "group":
            for cam in cam_or_group:
                update_lists(
                    cam,
                    image_folder,
                    cam_to_world_transforms,
                    image_filenames,
                    sensor_IDs,
                )
        else:
            # 4x4 transform
            update_lists(
                cam_or_group,
                image_folder,
                cam_to_world_transforms,
                image_filenames,
                sensor_IDs,
            )

    # Compute the lat lon using the transforms, because the reference values recorded in the file
    # reflect the EXIF values, not the optimized ones

    # Get the transform from the chunk to the earth-centered, earth-fixed (ECEF) frame
    chunk_to_epsg4327 = parse_transform_metashape(camera_file=camera_file)

    if chunk_to_epsg4327 is not None:
        # Compute the location of each camera in ECEF
        cam_locs_in_epsg4327 = []
        for cam_to_world_transform in cam_to_world_transforms:
            cam_loc_in_chunk = cam_to_world_transform[:, 3:]
            cam_locs_in_epsg4327.append(chunk_to_epsg4327 @ cam_loc_in_chunk)
        cam_locs_in_epsg4327 = np.concatenate(cam_locs_in_epsg4327, axis=1)[:3].T
        # Transform these points into lat-lon-alt
        transformer = pyproj.Transformer.from_crs(
            EARTH_CENTERED_EARTH_FIXED_CRS, LAT_LON_CRS
        )
        lat, lon, _ = transformer.transform(
            xx=cam_locs_in_epsg4327[:, 0],
            yy=cam_locs_in_epsg4327[:, 1],
            zz=cam_locs_in_epsg4327[:, 2],
        )
        lon_lats = list(zip(lon, lat))
    else:
        # TODO consider trying to parse from the xml
        lon_lats = None

    # Actually construct the camera objects using the base class
    super().__init__(
        cam_to_world_transforms=cam_to_world_transforms,
        intrinsic_params_per_sensor_type=sensors_dict,
        image_filenames=image_filenames,
        lon_lats=lon_lats,
        image_folder=image_folder,
        sensor_IDs=sensor_IDs,
        validate_images=validate_images,
        local_to_epsg_4978_transform=chunk_to_epsg4327,
    )

COLMAPCameraSet

Bases: PhotogrammetryCameraSet

Source code in geograypher/cameras/derived_cameras.py

class COLMAPCameraSet(PhotogrammetryCameraSet):

    def __init__(
        self,
        cameras_file: PATH_TYPE,
        images_file: PATH_TYPE,
        image_folder: typing.Union[None, PATH_TYPE] = None,
        validate_images: bool = False,
    ):
        """
        Create a camera set from the files exported by the open-source structure-from-motion
        software COLMAP as defined here: https://colmap.github.io/format.html

        Args:
            cameras_file (PATH_TYPE):
                Path to the file containing the camera models definitions
            images_file (PATH_TYPE):
                Path to the per-image information, including the pose and which camera model is used
            image_folder (typing.Union[None, PATH_TYPE], optional):
                Path to the folder of images used to generate the reconstruction. Defaults to None.
            validate_images (bool, optional):
                Ensure that the images described in images_file are present in image_folder.
                Defaults to False.

        Raises:
            NotImplementedError: If the camera is not a Simple radial model
        """
        # Parse the csv representation of the camera models
        cameras_data = pd.read_csv(
            cameras_file,
            sep=" ",
            skiprows=[0, 1, 2],
            header=None,
            names=(
                "CAMERA_ID",
                "MODEL",
                "WIDTH",
                "HEIGHT",
                "PARAMS_F",
                "PARAMS_CX",
                "PARAMS_CY",
                "PARAMS_RADIAL",
            ),
        )
        # Parse the csv of the per-image information
        # Note that every image has first the useful information on one row and then unneeded
        # keypoint information on the following row. Therefore, the keypoints are discarded.
        images_data = pd.read_csv(
            images_file,
            sep=" ",
            skiprows=lambda x: (x in (0, 1, 2, 3) or x % 2),
            header=None,
            names=(
                "IMAGE_ID",
                "QW",
                "QX",
                "QY",
                "QZ",
                "TX",
                "TY",
                "TZ",
                "CAMERA_ID",
                "NAME",
            ),
            usecols=list(range(10)),
        )

        # TODO support more camera models
        if np.any(cameras_data["MODEL"] != "SIMPLE_RADIAL"):
            raise NotImplementedError("Not a supported camera model")

        # Parse the camera parameters, creating a dict for each distinct camera model
        sensors_dict = {}
        for _, row in cameras_data.iterrows():
            # Note that the convention in this tool is for cx, cy to be defined from the center
            # not the corner so it must be shifted
            sensor_dict = {
                "image_width": row["WIDTH"],
                "image_height": row["HEIGHT"],
                "f": row["PARAMS_F"],
                "cx": row["PARAMS_CX"] - row["WIDTH"] / 2,
                "cy": row["PARAMS_CY"] - row["HEIGHT"] / 2,
                "distortion_params": {"r": row["PARAMS_RADIAL"]},
            }
            sensors_dict[row["CAMERA_ID"]] = sensor_dict

        # Parse the per-image information
        cam_to_world_transforms = []
        sensor_IDs = []
        image_filenames = []

        for _, row in images_data.iterrows():
            # Convert from the quaternion representation to the matrix one. Note that the W element
            # is the first one in the COLMAP convention but the last one in scipy.
            rot_mat = Rotation.from_quat(
                (row["QX"], row["QY"], row["QZ"], row["QW"])
            ).as_matrix()
            # Get the camera translation
            translation_vec = np.array([row["TX"], row["TY"], row["TZ"]])

            # Create a 4x4 homogenous matrix representing the world_to_cam transform
            world_to_cam = np.eye(4)
            # Populate the sub-elements
            world_to_cam[:3, :3] = rot_mat
            world_to_cam[:3, 3] = translation_vec
            # We need the cam to world transform. Since we're using a 4x4 representation, we can
            # just invert the matrix
            cam_to_world = np.linalg.inv(world_to_cam)
            cam_to_world_transforms.append(cam_to_world)

            # Record which camera model is used and the image filename
            sensor_IDs.append(row["CAMERA_ID"])
            image_filenames.append(Path(image_folder, row["NAME"]))

        # Instantiate the camera set
        super().__init__(
            cam_to_world_transforms=cam_to_world_transforms,
            intrinsic_params_per_sensor_type=sensors_dict,
            image_filenames=image_filenames,
            sensor_IDs=sensor_IDs,
            image_folder=image_folder,
            validate_images=validate_images,
        )

Functions

__init__(cameras_file, images_file, image_folder=None, validate_images=False)

Create a camera set from the files exported by the open-source structure-from-motion software COLMAP as defined here: https://colmap.github.io/format.html

Parameters:

Name	Type	Description	Default
cameras_file	PATH_TYPE	Path to the file containing the camera models definitions	required
images_file	PATH_TYPE	Path to the per-image information, including the pose and which camera model is used	required
image_folder	Union[None, PATH_TYPE]	Path to the folder of images used to generate the reconstruction. Defaults to None.	None
validate_images	bool	Ensure that the images described in images_file are present in image_folder. Defaults to False.	False

Raises:

Type	Description
NotImplementedError	If the camera is not a Simple radial model

Source code in geograypher/cameras/derived_cameras.py

def __init__(
    self,
    cameras_file: PATH_TYPE,
    images_file: PATH_TYPE,
    image_folder: typing.Union[None, PATH_TYPE] = None,
    validate_images: bool = False,
):
    """
    Create a camera set from the files exported by the open-source structure-from-motion
    software COLMAP as defined here: https://colmap.github.io/format.html

    Args:
        cameras_file (PATH_TYPE):
            Path to the file containing the camera models definitions
        images_file (PATH_TYPE):
            Path to the per-image information, including the pose and which camera model is used
        image_folder (typing.Union[None, PATH_TYPE], optional):
            Path to the folder of images used to generate the reconstruction. Defaults to None.
        validate_images (bool, optional):
            Ensure that the images described in images_file are present in image_folder.
            Defaults to False.

    Raises:
        NotImplementedError: If the camera is not a Simple radial model
    """
    # Parse the csv representation of the camera models
    cameras_data = pd.read_csv(
        cameras_file,
        sep=" ",
        skiprows=[0, 1, 2],
        header=None,
        names=(
            "CAMERA_ID",
            "MODEL",
            "WIDTH",
            "HEIGHT",
            "PARAMS_F",
            "PARAMS_CX",
            "PARAMS_CY",
            "PARAMS_RADIAL",
        ),
    )
    # Parse the csv of the per-image information
    # Note that every image has first the useful information on one row and then unneeded
    # keypoint information on the following row. Therefore, the keypoints are discarded.
    images_data = pd.read_csv(
        images_file,
        sep=" ",
        skiprows=lambda x: (x in (0, 1, 2, 3) or x % 2),
        header=None,
        names=(
            "IMAGE_ID",
            "QW",
            "QX",
            "QY",
            "QZ",
            "TX",
            "TY",
            "TZ",
            "CAMERA_ID",
            "NAME",
        ),
        usecols=list(range(10)),
    )

    # TODO support more camera models
    if np.any(cameras_data["MODEL"] != "SIMPLE_RADIAL"):
        raise NotImplementedError("Not a supported camera model")

    # Parse the camera parameters, creating a dict for each distinct camera model
    sensors_dict = {}
    for _, row in cameras_data.iterrows():
        # Note that the convention in this tool is for cx, cy to be defined from the center
        # not the corner so it must be shifted
        sensor_dict = {
            "image_width": row["WIDTH"],
            "image_height": row["HEIGHT"],
            "f": row["PARAMS_F"],
            "cx": row["PARAMS_CX"] - row["WIDTH"] / 2,
            "cy": row["PARAMS_CY"] - row["HEIGHT"] / 2,
            "distortion_params": {"r": row["PARAMS_RADIAL"]},
        }
        sensors_dict[row["CAMERA_ID"]] = sensor_dict

    # Parse the per-image information
    cam_to_world_transforms = []
    sensor_IDs = []
    image_filenames = []

    for _, row in images_data.iterrows():
        # Convert from the quaternion representation to the matrix one. Note that the W element
        # is the first one in the COLMAP convention but the last one in scipy.
        rot_mat = Rotation.from_quat(
            (row["QX"], row["QY"], row["QZ"], row["QW"])
        ).as_matrix()
        # Get the camera translation
        translation_vec = np.array([row["TX"], row["TY"], row["TZ"]])

        # Create a 4x4 homogenous matrix representing the world_to_cam transform
        world_to_cam = np.eye(4)
        # Populate the sub-elements
        world_to_cam[:3, :3] = rot_mat
        world_to_cam[:3, 3] = translation_vec
        # We need the cam to world transform. Since we're using a 4x4 representation, we can
        # just invert the matrix
        cam_to_world = np.linalg.inv(world_to_cam)
        cam_to_world_transforms.append(cam_to_world)

        # Record which camera model is used and the image filename
        sensor_IDs.append(row["CAMERA_ID"])
        image_filenames.append(Path(image_folder, row["NAME"]))

    # Instantiate the camera set
    super().__init__(
        cam_to_world_transforms=cam_to_world_transforms,
        intrinsic_params_per_sensor_type=sensors_dict,
        image_filenames=image_filenames,
        sensor_IDs=sensor_IDs,
        image_folder=image_folder,
        validate_images=validate_images,
    )