circle detection from drones camera

hello please who knows how can i write a matlab function that checks for rhe presence of a circle in a drones camera and then make the drone hover when it sees the circle

[Image Analyst]

You forgot to attach any images. It ranges from easy to very difficult depending on what the circles look like. Are they high contrast discs on a uniform background (very easy)? Are the faint rings with broken sections (very difficult)?

Anyway you have two tasks here: (1) locate the circle using image processing/computer vision software, and then once you've found it, (2) tell the drone somehow to move so that the circle is centered in the image (possibly, optional) and then stop moving (until further directions are given, not forever obviously).

[ugonna]

they are high contrast circles. thats the main issue how do i write a function that can take video from the camera as input in real time and time and track the circle as output. I dont really know much about image processing as i mostly use matlab for vehicle design. but i need it for the matlab mini drone competetion

Answer 1

[Image Analyst]

Since you have high contrast circles, see my Image Segmentation Tutorial in my File Exchange:

Image Analyst's File Exchange

It's a generic, general purpose demo of how to threshold an image to find blobs (high contrast circular coins on a dark uniform background), and then measure things about the blobs, and extract certain blobs based on their areas or diameters.

Get the web cam add-on from the Add-ons button on the tool ribbon.

help webcam

     WEBCAM creates webcam object to acquire frames from your webcam.
     CAMOBJ = WEBCAM returns a webcam object, CAMOBJ, that acquires images
     from the specified webcam. By default, this selects the first
     available webcam returned by WEBCAMLIST.
 
     CAMOBJ = WEBCAM(DEVICENAME) returns a webcam object, CAMOBJ, for
     webcam with the specified name, DEVICENAME. The webcam name can be
     found using the function WEBCAMLIST.
 
     CAMOBJ = WEBCAM(DEVICEINDEX) returns a webcam object, CAMOBJ, for
     webcam with the specified device index, DEVICEINDEX. The webcam device
     index is the index into the cell array returned by WEBCAMLIST.
 
     CAMOBJ = WEBCAM(..., P1, V1, P2, V2,...) constructs the webcam object,
     CAMOBJ, with the specified property values. If an invalid property
     name or property value is specified, the webcam object is not created.
 
     Creating WEBCAM object obtains exclusive access to the webcam.
 
     SNAPSHOT method syntax:
 
     IMG = snapshot(CAMOBJ) acquires a single frame from the webcam.
 
     [IMG, TIMESTAMP] = snapshot(CAMOBJ) returns the frame, IMG, and the
     acquisition timestamp, TIMESTAMP.
 
     WEBCAM methods:
 
     snapshot     - Acquire a single frame from the webcam.
     preview      - Activate a live image preview window.
     closePreview - Close live image preview window.
 
     WEBCAM properties:
 
     Name                 - Name of the webcam.
     Resolution           - Resolution of the acquired frame.
     AvailableResolutions - Cell array of list of available resolutions.
 
     The WEBCAM interface also supports the dynamic properties of the webcam
     that we can access programmatically. Some of these dynamic properties
     are Brightness, Contrast, Hue, Exposure etc. The presence of these
     properties in the WEBCAM object depends on the webcam that you connect
     to. Dynamic properties are not supported when using webcam in MATLAB
     Online.
 
     Example:
        % Construct a webcam object
        camObj = webcam;
 
        % Preview a stream of image frames.
        preview(camObj);
 
        % Acquire and display a single image frame.
        img = snapshot(camObj);
        imshow(img);
 
     See also WEBCAMLIST, SNAPSHOT, PREVIEW

    Documentation for webcam
       helpwin webcam

    Other uses of webcam

       webcam/webcam

[Jason Choo Chia Sheng]

Hi can i check how do we link a parrot minidrone camera for input to feed img into the matlab code?

[Vineeth Nair]

You can refer to these examples for image acquisition using the MATLAB Parrot sppkg.