Context Managers¶

Context managers can be used in order to avoid writing verbose boilerplate code like the following:

try:
    api.initialize()
    # User code.
except NxLibException as e:
    print(f"An NxLibException occured: Error Text: {e.get_error_text()}")
except Exception as e:
    print("Something bad happenend, that has been out of our control.\n")
    raise e

This can simplified with a context manager, who performs the initialization and takes care of the exception handling as follows:

with NxLib() as api:
    # User code.

See Examples for more on how the following classes can be used to simplify and beautify your code.

NxLib¶

class nxlib.context.NxLib¶

This class offers a simple to use interface for interacting with a normal NxLib. It implements the context manager protocol and thus can be used in a with statement, which automatically initializes the NxLib and takes care of the exception handling.

Parameters: path (str, optional) – The path to the NxLib shared library. Defaults to None.

NxLibRemote¶

class nxlib.context.NxLibRemote(hostname, port)¶

This class offers a simple to use interface for interacting with a remote NxLib. It implements the context manager protocol and thus can be used in a with statement, which automatically loads the remote NxLib, connects to the given hostname (and port) when entering the scope and automatically disconnects when exiting the scope. It also takes care of the exception handling.

Parameters

hostname (str) – The hostname of the remote NxLib.
port (int) – The port number of the remote NxLib.

MonoCamera¶

class nxlib.context.MonoCamera(serial, open_params={})¶

This class implements the context manager protocol and simplifies the handling of a mono camera.

It provides the camera tree node by calling get_node() or lets you directly access an NxLibItem within the camera node by using the [] operator.

Parameters

serial (str) – The serial number of the target camera.
open_params (dict) – Optional parameters for opening the target camera.

Raises

CameraTypeError – If the camera with the given serial number is not a monocular camera.
CameraNotFoundError – If no camera was found for the given serial number.
CameraOpenError – If the camera with the given serial cannot be opened.

capture()¶: Capture the image(s).

classmethod from_serial(serial, expected_types=None, open_params={})¶

get_node()¶

Get the camera tree node of the stereo camera the context object opens and represents.

Returns: The camera node of the stereo camera.
Return type: NxLibItem

rectify()¶: Rectify the captured images (requires capture() to be called first). Use this method only if you want to have the rectified raw images and no further data.

StereoCamera¶

class nxlib.context.StereoCamera(serial, open_params={})¶

This class implements the context manager protocol and simplifies the handling of an Ensenso stereo camera.

It provides the camera tree node by calling get_node() or lets you directly access an NxLibItem within the camera node by using the [] operator.

Parameters

serial (str) – The serial number of the target camera.
open_params (dict) – Optional parameters for opening the target camera.

Raises

CameraTypeError – If the camera with the given serial number is not a stereo camera.
CameraNotFoundError – If no camera was found for the given serial number.
CameraOpenError – If the camera with the given serial cannot be opened.

capture()¶: Capture the image(s).

compute_disparity_map()¶

Compute the disparity map (requires capture() to be called first).

Returns: The disparity map node.
Return type: NxLibItem

compute_point_map()¶

Compute the point map (requires compute_disparity_map() to be called first).

Returns: The point map node.
Return type: NxLibItem

compute_texture()¶

Compute the texture (requires compute_point_map() to be called first).

Returns: The texture node.
Return type: NxLibItem

classmethod from_serial(serial, expected_types=None, open_params={})¶

get_disparity_map()¶

The computed disparity map (requires compute_disparity_map()).

Returns: A byte buffer containing the disparity map.
Return type: Object

get_node()¶

Get the camera tree node of the stereo camera the context object opens and represents.

Returns: The camera node of the stereo camera.
Return type: NxLibItem

get_point_map()¶

The computed point map (requires compute_point_map()).

Returns: A byte buffer containing the point map.
Return type: Object

get_texture()¶

The computed texture (requires compute_texture()).

Returns: A byte buffer containing the texture.
Return type: Object

rectify()¶: Rectify the captured images (requires capture() to be called first). Use this method only if you want to have the rectified raw images and no further data.

StructuredLightCamera¶

class nxlib.context.StructuredLightCamera(serial, open_params={})¶

This class implements the context manager protocol and simplifies the handling of an Ensenso structured light camera and has the same functionality as a stereo camera except that it does not have a disparity map.

It provides the camera tree node by calling get_node() or lets you directly access an NxLibItem within the camera node by using the [] operator.

Parameters

serial (str) – The serial number of the target camera.
open_params (dict) – Optional parameters for opening the target camera.

Raises

CameraTypeError – If the camera with the given serial number is not a structured light camera.
CameraNotFoundError – If no camera was found for the given serial number.
CameraOpenError – If the camera with the given serial cannot be opened.
CameraDisparityMapError – If a disparity map is requested.

capture()¶: Capture the image(s).

compute_disparity_map()¶: Does nothing, because a structured light camera does not have a disparity map. Existing for compatibility reasons.

compute_point_map()¶

Compute the point map (requires capture() to be called first).

Returns: The point map node.
Return type: NxLibItem

compute_texture()¶

Compute the texture (requires compute_point_map() to be called first).

Returns: The texture node.
Return type: NxLibItem

get_node()¶

Get the camera tree node of the stereo camera the context object opens and represents.

Returns: The camera node of the stereo camera.
Return type: NxLibItem

get_point_map()¶

The computed point map (requires compute_point_map()).

Returns: A byte buffer containing the point map.
Return type: Object

get_texture()¶

The computed texture (requires compute_texture()).

Returns: A byte buffer containing the texture.
Return type: Object

rectify()¶: Rectify the captured images (requires capture() to be called first). Use this method only if you want to have the rectified raw images and no further data.

Exceptions¶

exception nxlib.context.CameraTypeError¶: Raised if camera has the wrong type (Mono/Stereo/StructuredLight).

exception nxlib.context.CameraNotFoundError¶: Raised if no camera is found for a given serial number.

exception nxlib.context.CameraOpenError¶: Raised if a camera cannot be opened.

exception nxlib.context.CameraDisparityMapError¶: Raised if a non-existing disparity map is requested.