A maximum of 3 markers can only be detect

[gotecq-thudang]

Thank you for sharing. i tried your demo test but only up to 3 markers can be detect Hope you could help

[ValYouW]

I don't recall such limitation, did you try to debug it?

[gotecq-thudang]

I don't recall such limitation, did you try to debug it?

I checked and found this code limits the number of markers that can be detected res.size() < 3

`vector<ArucoResult> ArucoDetector::detectArucos(Mat frame, int misses) { vector<ArucoResult> res; vector<vector<Point2f>> cands = findSquares(frame);

for (int i = 0; i < cands.size() && res.size() < 3; ++i) {
	vector<Point2f> cnt = cands[i];
	vector<int> sig = getContoursBits(frame, cnt, 36);
	for (int j = 0; j < m_dict.sigs.size(); ++j) {
		if (equalSig(sig, m_dict.sigs[j], misses)) {
			ArucoResult ar;
			ar.corners = cnt;
			ar.index = j;
			res.push_back(ar);
			break;
		}
	}
}

return res;

}`

I tried increasing the size, it worked but it seemed unstable, Is there anything I can do to make it run more stable?, thank you

[ValYouW]

What do you mean more stable? If you want the detection to be more "flexible" you can increase the "misses" parameter I think (how many aruco "bits" can be missed and still consider the marker valid)

[gotecq-thudang]

In my case there are 4 markers, but the detection will change back and forth between 3 and 4 markers. What can I do to detect 4 fixed markers? Hope you could help

[ValYouW]

I don't think it's the number of markers that matter but the location of the marker in the frame and its angle that makes a marker to "flicker"

[gotecq-thudang]

yes, it flicker, but I don't think it's a matter of location and angle

https://github.com/ValYouW/flutter-opencv-stream-processing/assets/126755528/68b22c36-d195-4bdc-8831-184648fa3318

[ValYouW]

It actually looks pretty good I think, my experience with image processing is that there is always some noise when processing live camera feed. In the video I see the printed marker is not fully black, there are some white spots, try to paint then black and test.

[angelru]

@ValYouW I'm trying to use your example, but I'm using the library https://pub.dev/packages/opencv_dart. Do you think I could make a migration?. Why do you use an image as a detector? My detector is black squares but I look for them in the photo taken with the camera

[ValYouW]

@angelru I am not familiar with that library, it seems like a relatively new library. But if it provides all the OpenCV methods that you need easily and efficiently that would be cool. Not I understand you question "Why do you use an image as a detector", if I remember correctly I use an aruco marker.

[angelru]

@ValYouW

I'm trying to follow your example and load the marker.png from the assets in principle, I don't know which dictionary the aruco marker uses.

 final markedData = await rootBundle.load('assets/images/marker.png');
   final markedbytes = markedData.buffer.asUint8List();
   var imgMarked = await cv.imdecodeAsync(markedbytes, cv.IMREAD_COLOR);

   final detector = cv.ArucoDetector.create(
     cv.ArucoDictionary.predefined(cv.PredefinedDictionaryType.DICT_4X4_250),
     cv.ArucoDetectorParameters.empty(),
   );

   final (_, ids, _) = detector.detectMarkers(imgMarked);
   int idMarked = ids.first;

There are never ids

[ValYouW]

Ah, I don't know how the builtin aruco detector of ooencv works, I created my own market. I would guess they have a set of predefined markers, or you should initialize a dictionary with your own market(s). You will have to rear ooencv docs...