OpenCV.js unable to track coloured circle and draw circle on target.

asked 2019-05-15 02:09:26 -0500

updated 2019-05-16 02:35:21 -0500

berak gravatar image

Hi, I have a code to track a random input target and draw a rectangle on top of my target, but I need to track(Green colored circle and draw a circle on my target, I have searched for it in OpenCV.js but I couldn't find it, help me with any link which can help me, my rectangle code is below

let video = document.getElementById('videoInput');
let cap = new cv.VideoCapture(video);

// take first frame of the video
let frame = new cv.Mat(video.height, video.width, cv.CV_8UC4);
cap.read(frame);

// hardcode the initial location of window
let trackWindow = new cv.Rect(150, 60, 63, 125);

// set up the ROI for tracking
let roi = frame.roi(trackWindow);
let hsvRoi = new cv.Mat();
cv.cvtColor(roi, hsvRoi, cv.COLOR_RGBA2RGB);
cv.cvtColor(hsvRoi, hsvRoi, cv.COLOR_RGB2HSV);
let mask = new cv.Mat();
let lowScalar = new cv.Scalar(30, 30, 0);
let highScalar = new cv.Scalar(180, 180, 180);
let low = new cv.Mat(hsvRoi.rows, hsvRoi.cols, hsvRoi.type(), lowScalar);
let high = new cv.Mat(hsvRoi.rows, hsvRoi.cols, hsvRoi.type(), highScalar);
cv.inRange(hsvRoi, low, high, mask);
let roiHist = new cv.Mat();
let hsvRoiVec = new cv.MatVector();
hsvRoiVec.push_back(hsvRoi);
cv.calcHist(hsvRoiVec, [0], mask, roiHist, [180], [0, 180]);
cv.normalize(roiHist, roiHist, 0, 255, cv.NORM_MINMAX);

// delete useless mats.
roi.delete(); hsvRoi.delete(); mask.delete(); low.delete(); high.delete(); hsvRoiVec.delete();

// Setup the termination criteria, either 10 iteration or move by atleast 1 pt
let termCrit = new cv.TermCriteria(cv.TERM_CRITERIA_EPS | cv.TERM_CRITERIA_COUNT, 10, 1);

let hsv = new cv.Mat(video.height, video.width, cv.CV_8UC3);
let hsvVec = new cv.MatVector();
hsvVec.push_back(hsv);
let dst = new cv.Mat();
let trackBox = null;

const FPS = 30;
function processVideo() {
    try {
        if (!streaming) {
            // clean and stop.
            frame.delete(); dst.delete(); hsvVec.delete(); roiHist.delete(); hsv.delete();
            return;
        }
        let begin = Date.now();

        // start processing.
        cap.read(frame);
        cv.cvtColor(frame, hsv, cv.COLOR_RGBA2RGB);
        cv.cvtColor(hsv, hsv, cv.COLOR_RGB2HSV);
        cv.calcBackProject(hsvVec, [0], roiHist, dst, [0, 180], 1);

        // apply camshift to get the new location
        [trackBox, trackWindow] = cv.CamShift(dst, trackWindow, termCrit);

        // Draw it on image
        let pts = cv.rotatedRectPoints(trackBox);
        cv.line(frame, pts[0], pts[1], [255, 0, 0, 255], 3);
        cv.line(frame, pts[1], pts[2], [255, 0, 0, 255], 3);
        cv.line(frame, pts[2], pts[3], [255, 0, 0, 255], 3);
        cv.line(frame, pts[3], pts[0], [255, 0, 0, 255], 3);
        cv.imshow('canvasOutput', frame);

        // schedule the next one.
        let delay = 1000/FPS - (Date.now() - begin);
        setTimeout(processVideo, delay);
    } catch (err) {
        utils.printError(err);
    }
};

// schedule the first one.
setTimeout(processVideo, 0);
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