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2017-04-11 01:35:40 -0500 answered a question Opencv IP Camera Error

Compilethe latest version from github OpenCV (Master branch). It works fine.

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2017-01-24 06:24:56 -0500 asked a question Real-Time Multi-Object Tracking with Learning

My Goal is to have real-time MultiTracker with Learning.
I used Kalman filter to track an object but i found errors in the estimation while tracking.
The object was not been tracked continuously. I want to implement some learning mechanism along with Tracking.
One way i thought of doing this is,
1) calculate the average HSV of a particular roi then store that HSV value in a vector(Scalar or Vec3b)
2) Compare the new HSV value (average from some ROI) with all previous HSV values present in vector collection.
3)If the new HSV value did not match with the HSV values in vector then track this as a new separate object.
4) else if the new roi matched HSV values in vector, then it is said to be the same object present in the roi. continue tracking old object.
5) Have some regular time based checking to remove old HSV values in vector.

I tried KCF, MIL e.t.c they are not realtime. can you recommend any realtime learning mecahnism or ways to improve above proposed one.

2017-01-06 04:05:13 -0500 commented question Build OpenCV with OpenCL support

Thank you. I tried test opencl code and it gave excellent results. Can you please explain this line in testOCL_OCV32.cpp. I understood that m is the average time taken, but sqrt(v) has +/- what does the value indicate and why v is required?

2017-01-03 04:13:09 -0500 commented question Build OpenCV with OpenCL support

Thanks for your reply. I am using the latest version of OpenCV from github. I am using face_detection sample code and replaced Mat with UMat.The breakpoint at this line is triggered. but retval is 0.

I tried on both AMD processor + Carrizo also on Intel processor + Nvidea Graphics in windows 10 and windows 7. No performance improvement anywhere. How did you get nvcompiler.dll ? I installed AMD-APP-SDK like said in question above, but that didn't help me. also tried installing Intel OpenCL SDK & INtel OpenCL Runtimes..No luck with that as well.

2017-01-01 05:48:05 -0500 asked a question Build OpenCV with OpenCL support

in CMake, I built OpenCV with OpenCL Enable ON(It automatically detected the OPENCL_INCLUDE_DIR path but the OPENCL_LIBRARY was empty, even after clicking config. for OPENCL_LIBRARY i don't see browse button either .. after generating opencv binaries then i run the below code

#include <iostream>
#include <fstream>
#include <string>
#include <iterator>
#include <opencv2/opencv.hpp>
#include <opencv2/core/ocl.hpp>

int main()
  if (!cv::ocl::haveOpenCL())       
      cout << "OpenCL is not avaiable..." << endl;          
   else cout << "OpenCL is AVAILABLE! :) " << endl; //this is the output


   cout << context.ndevices() << " GPU devices are detected." << endl; 
   for (int i = 0; i < context.ndevices(); i++)
     cv::ocl::Device device = context.device(i);
     cout << "name:              " << << endl;
     cout << "available:         " << device.available() << endl;
     cout << "imageSupport:      " << device.imageSupport() << endl;
     cout << "OpenCL_C_Version:  " << device.OpenCL_C_Version() << endl;
     cout << endl;
    } //this works & i can see my video card name & opencl version

When i make use of UMat to measure the performance, the performance with(UMat) or without(Mat) OpenCL did not make any difference.

I downloaded AMD-APP-SDK from this link and tried to build but there was no OpenCL binaries (instead i saw opengl dll files[glew32.dll & glut32.dll]. How do i build OpenCV with OpenCL by linking the OPENCL_LIBRARY?

2016-11-25 09:47:52 -0500 commented question opencv_ffmpeg module crash (IP Camera)

cap.IsOpened() always returns true even when Wi-Fi is turned off.

2016-11-25 07:20:56 -0500 asked a question opencv_ffmpeg module crash (IP Camera)

I'm using IP webcam android app(It converts mobile camera into IP web camera).
I'm running below code in Visual Studio 2015 with OpenCV 3.1.

VideoCapture cap; Mat img;"");
        cap>>img;  //code crashes here
         cout<<"camera Closed"<<endl;
      } catch(...{}    

Getting below error. If the internet connection is slow or if the Wi-Fi is disconnected in my android device the program crashes

Exception thrown at 0x0BF2F6F0 (opencv_ffmpeg310.dll) in test.exe: 0xC0000005: Access violation reading location 0x00000020.

If there is a handler for this exception, the program may be safely continued.

even if the code is wrapped within try catch block, it crashes!

Should I use try {} catch (...) block in source file, if yes, then where should I use this?
I referred this link but did not find the right answer.

2016-11-24 01:05:09 -0500 asked a question CMake error while building MultiTarget-tracker library.

I'm trying to build Multitarget-tracker using CMake in windows. Initially i had the warning below,

You should manually point CMake variable OpenCV_DIR to your build of OpenCV library. Call Stack (most recent call first): CMakeLists.txt:57 (find_package)

I manually pointed out the directory of build version of OpenCV library and tried to build. I referred this link while building.


CMake Warning at CMakeLists.txt:23 (FIND_PACKAGE): Found package configuration file: C:/OpenCV/opencv/build/x86/vc12/lib/OpenCVConfig.cmake but it set OpenCV_FOUND to FALSE so package "OpenCV" is considered to be NOT FOUND.

I checked the OpenCV_FOUND, but after i press 'configure' again, it automatically unchecks.

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2016-11-11 22:38:47 -0500 asked a question Getting status of multiple objects.

I tried the tracker algorithms (MIL,BOOSTING,MEDIANFLOW,TLD and KCF) , apart from KCF the rest of the algorithms are very slow while tracking objects. Which is the best algorithm for tracking multiple objects?

I tried camshift as well, if we move the object is out of the frame, camshift still tracks(marks) somewhere within the frame. How to get the status of the tracker in Camshift or in any other algorithm. My Goal is to track multiple objects also check if object present within the frame.

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2016-11-11 00:37:42 -0500 commented answer Best method to track multiple objects?

I tried camshift, if move the object out of the frame, the object is still tracked(marked) within the frame(at some region). How to get the status of the tracker in Camshift ?

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2016-09-28 00:37:04 -0500 asked a question How to convert SFML image to OpenCV Mat in c++?

Below code is used to convert an OpenCV Mat image into SFML image. How to convert SFML image back to Mat image?

 cv::Mat frameBGR, frameBGRA;   
 sf::Image image;    
 frameRGBA.rows, frameRGBA.ptr());

If texture or sprite can't be converted to OpenCV Mat,then is it possible to convert sf::Image to OpenGL and convert it back to cv::Mat

    sf::Texture texture;
    sf::Event event;
    sf::Sprite sprite;

Update: I referred this post, but still was not able to convert.

    void* buffer = &image; 
    cv::Mat image_mat = cv::Mat(cvSize(500, 500),CV_8UC4, buffer, cv::Mat::AUTO_STEP);  
    cvtColor(image_mat, converted,CV_RGBA2BGR);

It crashes at below line of code (when i display image )

imshow("img", converted);