Python-openCV: Extracting (x,y) coordinates of point features on an image
Hi all, I am trying to extract the (x,y) coordinates of the the four corners of a wooden rectangular plank image and apply that to a real-time video feed. What I have in mind is: 1) read image and...
View ArticleResidual error from fundamental matrix
Hi guys, as in the previous topics I made I'm still working on self calibration stuff. I'm generating the data for the evaluation but I end out with some strange error computing the residual error as...
View ArticleCoordinate system for P1, P2 in triangulatepoint
Hey, looking at the mathematics is it correct that if P1 and P2 (projection matrices for camera 1 and 2) are both defined in reference to some world coordinate frame, then the output of...
View ArticleLoading a .yml file in a SVM
Hi everyone, I trained an SVM and saved the result in a .yml file thanks to svm->save(filename). However when on the second run I use Ptr svm = SVM::load(filename); the whole program doesn't give...
View Articlein opencv.js function cv.findTransformECC what is inputMask?
How do you represent "inputMask=None" 6th argument in Javascript? "null" does not work. The argument IS NOT optional as it outlines in docs. [findTransformECC]...
View Articleandroid opencv optical mark recognition
I want to use opencv for OMR sheet or Bubble sheet .I dont have fix number of questions or columns in my omr sheet so i am trying to detetct rows and column (also i need to detect the title of the...
View ArticleLink error cannot open input file opencv_world440.lib when trying to install...
I am following this tutorial to install OpenCV with extra modules and CUDA: https://jamesbowley.co.uk/accelerate-opencv-4-2-0-build-with-cuda-and-python-bindings/ I got to the step where I see the...
View Article"no element rtspsrc" gstreamer+opencv in win10
Hello, I'm trying to receive rtsp source from gstreamer, it can shows video stream correctly by enter this command line: ./gst-launch-1.0.exe -v rtspsrc location=rtsp://192.168.1.2:8554/test latency=0...
View ArticleVideoCapture.read blocking Java thread in RUNNING state
I'm using OpenCV's Java bindings with Gstreamer as a backend API for the VideoCapture class. As expected `VideoCapture#read(Mat)` is a blocking call but using the VisualVM profiler I can see that the...
View ArticleHow to install openCV in Android Studio 4.0.0?
Hello Since there is no Android download link for either of the 4.0.0 versions of openCV, which one do I install for my Android Studio? 
View ArticleWhat does the history of this function “createBackgroundSubtractorMOG2” means?
I only see this description in this [link](https://docs.opencv.org/master/de/de1/group__video__motion.html#ga2beb2dee7a073809ccec60f145b6b29c), it hasn't a very detailed explanation, so I'd like to...
View ArticleAppropriate combination of Aruco markers for small sizes
Hello! I am trying to track the pose of an object that is relatively small. It has a flat surface of about 3cm x 3cm on which I can stick an Aruco marker of size 2.5cm x 2.5cm and perform detection and...
View ArticleAndroid dnn in native C++
Hello, i succesfully linked opencv to my android c++ native app.. now I encountered a problem where i cannot read my models (ex. YOLO) I pasted them here: */storage/emulated/0/DCIM/ * but when running...
View ArticleHow to use contours and Harris corners Functions in solvePnP?
Hi I have code to extract the 2D coordinates from prior knowledge, using e.g. Harris Corners and contour of the object. I'm using these features because the objects are without textures so ORB or SIFT...
View Articleerror VideoCapture cap.open(), opencv4.1 Android C++
This is my code： ``` cv::VideoCapture cap; cap.open(0); if (!cap.isOpened()) ``` The following exception will appear and i tried the way given on the official website ``` Traceback (most recent call...
View Articlebody height measurement and length of arm with OpenCV from a single still...
hi, I'm working for my final year project which required to measure height of human and length of arm using single still image capture on raspberry pi camera with known reference distance from the...
View ArticleWhy are the coordinates of each crack not steady
I am trying to get the coordinates to keep still but when measure the x distance from the reference point (0,0) to the centroid of the crack (or contour) it would decrease as it is moving from left to...
View ArticleConverting ArUco axis-angle to Unity3D Quaternion
I'm interested in comparing the quaternions of an object presented in the real-world (with ArUco marker on top of it) and its simulated version in Unity3D. To do this, I generated different scenes in...
View ArticleOpenCV - OpenGL - OpenCL Interop
Hi guys I'm writing a very basic program to monitor performance when copying from a cv::ogl::Texture2D to a cv::ogl::Buffer (using the copyTo function), and from there to an OpenCL cv::UMat (using...
View ArticleTransform gray image to create a pattern effect on while pixels given a mask
I need to create a pattern on white pixels that basically turn whites into blacks or a given brightness (50 of 255 for example) given a mask, it need to follow some rules: 1) Have a margin, for example...
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