CODEWITHSUNDEEP
opencvimplementationsift
Ria George
Ria George

Reputation: 393

Opencv:Run time error in SIFT implementation

I am an entry level programmer in Opencv2.3 and playing around with codes available in the internet and various useful resources. There is a code implemented by Stack User User:Froyo in his website website. When I tried executing the code, the program exits as soon as I drag and draw a bounding box around the region of interest. The Runtime error is

Unhandled exception at 0x7509c41f (KernelBase.dll) in SIFT_Track.exe: Microsoft C++ exception: cv::Exception at memory location 0x0036f144..
Bad argument: <img is empty or has an incorrect type) in unknown function , file c:\Users\vp\work\ocv\opencv\modules\features2d\src\sift.cpp line 1681
Opencv Error: Assertion failed <0< =roi.x && <roi.width && roi.x+roi.width etc...c:\Users\vp\work\ocv\opencv\modules\core\src\matrix.cpp line 303

The source code is available for download github. Can somebody please help in resolving what is the error so that the program may run at my end. I have no clue what seems to be the problem!

Upvotes: 2

Views: 390

Answers (1)

shanqsys
shanqsys

Reputation: 148

Does the error occur after the mouse button up?

Can you check if the ROI is selected correctly by just outputting the position of the point1 and point2?

std::cout << "point1" << point1 << std::endl;

just bellow the mouse callback function in the main() function?

I am not able to test the code at the moment. For understanding the principle and using OpenCV for tracking feature, I suggest you start from 2D images. Please refer to Features2D + Homography to find a known object

I tested the code. Here is the problem: the new position of ROI could cause error when its value is larger than the resolution of your webcam. So I modify the newPoint() function as bellow and it works properly

void newPoints(vector<double> diff, Point cen, double rad)
{
printf("rad = %lf\tcen=(%d, %d)\n",rad, cen.x, cen.y);
printf("%f %f %f %f\n",diff[0], diff[1], diff[2], diff[3]);
point1.x = cen.x - rad - diff[0] >= 0 ? cen.x - rad - diff[0]:0;
point1.x = cen.x - rad - diff[0] <= img.cols ? cen.x - rad - diff[0]:img.cols;

point1.y = cen.y - rad - diff[1] >= 0 ? cen.y - rad - diff[1]:0;
point1.y = cen.y - rad - diff[1] <= img.rows ? cen.y - rad - diff[1]:img.rows;

point2.x = cen.x + rad + diff[2] >= 0 ? cen.x + rad + diff[2]:0;
point2.x = cen.x + rad + diff[2] <= img.cols ? cen.x + rad + diff[2]:img.cols;

point2.y = cen.y + rad + diff[3] >= 0 ? cen.y + rad + diff[3]:0;
point2.y = cen.y + rad + diff[3] <= img.rows ? cen.y + rad + diff[3]:img.rows;

printf("(%d, %d), (%d, %d)\n", point1.x, point1.y, point2.x, point2.y);
}

Upvotes: 1

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