camera - Connection to USB or CSI camera - MATLAB (original) (raw)

Connection to USB or CSI camera

Description

This object represents a connection from the MATLAB® software to a web camera attached to the NVIDIA DRIVE® or Jetson™ hardware. To create this object, use the camera function. To configure the web camera settings, use the object properties listed in Properties. To interact with the web camera, use this object with the functions listed in Object Functions.

Creation

Syntax

Description

[cam](#mw%5F2794e80c-1f2c-4897-bc79-bafd793b65a8) = camera([hwObj](#mw%5Ff09e7563-39cd-472d-9fab-660055854437%5Fsep%5Fmw%5Fbcc65819-faa5-4997-9bca-35a8da7d894a),[cameraName](#mw%5Fc253e712-8051-4d43-9baf-71bb30f53791),[resolution](#mw%5Fe8b3d1ac-8847-422e-956f-7f09d73338c0)) creates a camera object cam and connects to a camera that is attached to the NVIDIA DRIVE or Jetson hardware. The camera function supports cameras connected to USB and camera peripheral interfaces (CSI) of the target board. When thecamera object is created, it connects to the camera and establishes exclusive access to stream data. You can preview the data and acquire images by using the snapshot function.

Note

Because the software establishes exclusive access to the camera, you cannot associate more than one object to the same camera. Before code generation and execution, you must clear the camera object by using theclear function.

The CSI drivers on the NVIDIA® target do not support odd pixel values for the resolution.

example

[cam](#mw%5F2794e80c-1f2c-4897-bc79-bafd793b65a8) = camera(___,'VideoDevice',['VideoDeviceID'](#mw%5F55b1f62e-5c6d-4ec7-84d9-26a5051c3637)) creates a camera object cam and connects to a camera by using Linux® device number. If your target hardware is connected to multiple cameras with the same name, use the 'VideoDevice' argument to specify the camera to create a connection to.

[cam](#mw%5F2794e80c-1f2c-4897-bc79-bafd793b65a8) = camera(___,'PixelFormat',['Format'](#mw%5Fb87d97a3-4197-40ac-b9c8-e3ae6c92e882)) creates a camera object cam specifying the frame format of the incoming data.

Input Arguments

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Connection to a specific NVIDIA hardware board, specified as a jetson or drive object.

Name of the camera attached to the target hardware, specified as a string or character vector. This argument identifies a particular camera by its name. You can use the exact name that is returned by the getCameraList function, such as 'Microsoft LifeCam VX-2000'

The height and width of the image in pixels that the camera captures, specified as a 1-by-2 numeric array. Use the getCameraList function to get a list of the Available Resolutions supported by the cameras connected to the target board. You can specify height and width values that are multiples of the resolutions supported by the camera. The CSI drivers on the NVIDIA target do not support odd pixel values for the resolution.

Create a camera object by using the Linux device number of the camera, specified as a character vector. If your target hardware is connected to multiple cameras with the same name, use the'VideoDevice' argument along with a value to identify the camera to create the connection to. Use the getCameraList function to get the Video Device number of the cameras connected to the target board.

Example: camera(hwObj,"vi-output, ov5693 2-0036",[2592 1944],'VideoDevice','/dev/video0')

Specify the format of the frames from the camera.

Example: camera(hwObj,"vi-output, ov5693 2-0036",[2592 1944],'PixelFormat','MJPG')

Output Arguments

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Connection to a camera that is attached to the NVIDIA DRIVE or Jetson hardware. To capture images from the camera, use thecam object with the snapshot function.

Properties

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This property is read-only.

Camera name, returned as a character vector.

Example: 'vi-output, ov5693 2-0036'

This property is read-only.

The height and width of the image in pixels that the camera captures, returned as a 1-by-2 numeric array.

Example: [2592 1944]

This property is read-only.

This property is read-only.

The Linux device number of the camera, returned as a character vector.

Example: '/dev/video0'

Object Functions

Examples

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You can connect from the MATLAB software to the onboard CSI camera connected to an NVIDIA platform and capture images from this camera.

Create a live hardware connection from the MATLAB software to the NVIDIA hardware by using the jetson function. To create a live hardware connection object, provide the host name or IP address, user name, and password of the target board. For example,

hwobj = jetson('jetson-board-name','ubuntu','ubuntu');

To find the camera name, use the getCameraList function.

camlist = getCameraList(hwobj)

camlist =

2×3 table

         Camera Name              Video Device            Available Resolutions        
______________________________    _____________    ____________________________________

"vi-output, ov5693 2-0036"        "/dev/video0"    "[1280 720],[2592 1458],[2592 1944]"
"Microsoft LifeCam Cinema(TM)"    "/dev/video1"    "(View resolutions)"

If the function does not list a USB based camera, try reconnecting the USB webcam and run the updatePeripheralInfo function. This function tries to scan the available webcams on the target when there is an addition or deletion.

updatePeripheralInfo(hwobj);

Create a camera object, cam using the name of the camera from the list and a supported resolution. For multiple cameras with the same name, use the 'VideoDevice' argument to identify a camera by its Linux device number. The cam object has the following camera properties.

cam = camera(hwobj,"vi-output, ov5693 2-0036",[2592 1944])

cam =

camera with properties:

       Name: 'vi-output, ov5693 2-0036'
  ImageSize: [2592 1944]
VideoDevice: '/dev/video0'

To capture a frame of image from this camera and display it in MATLAB, use the following commands.

img = snapshot(cam); figure(); imagesc(img); drawnow;

To change the resolution of the image capture, you must clear thecamera object by using the clear function and then use thecamera function to connect to the camera again.

clear cam; cam = camera(hwobj,"vi-output, ov5693 2-0036",[1280 720]);

Extended Capabilities

Version History

Introduced in R2019a

See Also

Functions

Objects

Topics