OPENCV: PCA application error in image_proc - c++

Question

Base from this here.
I got this error and this is the only one left for almost 3 days of my trial and error in debugging:
Unhandled exception at 0x000007FEEC6315A4 (opencv_imgproc242.dll) in PCA.exe: 0xC0000005: Access violation reading location 0xFFFFFFFFFFFFFFFF.
Please can someone here who can help me with this. Im currently using VS2012 and my os is win7 64-bit. I configure my opencv 2.4.2 following this blog.
Please help!

Answer 1

I've corrected some minor bugs (and now it works perfect for me):
#include <iostream>
#include <opencv2/opencv.hpp>
using namespace cv;
using namespace std;
double getOrientation(vector<Point> &pts, Mat &img)
{
if (pts.size() == 0) return false;
//Construct a buffer used by the pca analysis
Mat data_pts = Mat(pts.size(), 2, CV_64FC1);
for (int i = 0; i < data_pts.rows; ++i)
{
data_pts.at<double>(i, 0) = pts[i].x;
data_pts.at<double>(i, 1) = pts[i].y;
}
//Perform PCA analysis
PCA pca_analysis(data_pts, Mat(), CV_PCA_DATA_AS_ROW);
//Store the position of the object
Point pos = Point(pca_analysis.mean.at<double>(0, 0),
pca_analysis.mean.at<double>(0, 1));
//Store the eigenvalues and eigenvectors
vector<Point2d> eigen_vecs(2);
vector<double> eigen_val(2);
for (int i = 0; i < 2; ++i)
{
eigen_vecs[i] = Point2d(pca_analysis.eigenvectors.at<double>(i, 0),
pca_analysis.eigenvectors.at<double>(i, 1));
eigen_val[i] = pca_analysis.eigenvalues.at<double>(i);
}
// Draw the principal components
circle(img, pos, 3, CV_RGB(255, 0, 255), 2);
line(img, pos, pos + 0.02 * Point(eigen_vecs[0].x * eigen_val[0], eigen_vecs[0].y * eigen_val[0]) , CV_RGB(255, 255, 0));
line(img, pos, pos + 0.02 * Point(eigen_vecs[1].x * eigen_val[1], eigen_vecs[1].y * eigen_val[1]) , CV_RGB(0, 255, 255));
return atan2(eigen_vecs[0].y, eigen_vecs[0].x);
}
int main()
{
// Read the image
Mat bw, img = imread("pca_test1.jpg",1); // "pca_test2.jpg"
// Convert it to greyscale
cvtColor(img, bw, COLOR_BGR2GRAY);
// Apply thresholding
threshold(bw, bw, 150, 255, cv::THRESH_BINARY);
// Find all objects of interest
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
findContours(bw, contours, hierarchy, cv::RETR_LIST, cv::CHAIN_APPROX_NONE);
// For each object
for (size_t i = 0; i < contours.size(); ++i)
{
// Calculate its area
double area = contourArea(contours[i]);
// Ignore if too small or too large
if (area < 1e2 || 1e5 < area) continue;
// Draw the contour
drawContours(img, contours, i, CV_RGB(255, 0, 0), 2, 8, hierarchy, 0);
// Get the object orientation
getOrientation(contours[i], img);
}
imshow("Image", img);
char key;
while (true)
{
key = waitKey(1);
if (key == 'q') break;
}
cv::destroyAllWindows();
return 0;
}