I've done it this way in the past:
cv::Mat R = cv::estimateRigidTransform(p1,p2,false);
if(R.cols == 0)
{
continue;
}
cv::Mat H = cv::Mat(3,3,R.type());
H.at<double>(0,0) = R.at<double>(0,0);
H.at<double>(0,1) = R.at<double>(0,1);
H.at<double>(0,2) = R.at<double>(0,2);
H.at<double>(1,0) = R.at<double>(1,0);
H.at<double>(1,1) = R.at<double>(1,1);
H.at<double>(1,2) = R.at<double>(1,2);
H.at<double>(2,0) = 0.0;
H.at<double>(2,1) = 0.0;
H.at<double>(2,2) = 1.0;
cv::Mat warped;
cv::warpPerspective(img1,warped,H,img1.size());
which is the same as David Nilosek suggested: add a 0 0 1 row at the end of the matrix
this code warps the IMAGES with a rigid transformation.
I you want to warp/transform the points, you must use perspectiveTransform
function with a 3x3 matrix ( http://docs.opencv.org/modules/core/doc/operations_on_arrays.html?highlight=perspectivetransform#perspectivetransform )
tutorial here:
http://docs.opencv.org/doc/tutorials/features2d/feature_homography/feature_homography.html
or you can do it manually by looping over your vector and
cv::Point2f result;
result.x = point.x * R.at<double>(0,0) + point.y * R.at<double>(0,1) + R.at<double>(0,2);
result.y = point.x * R.at<double>(1,0) + point.y * R.at<double>(1,1) + R.at<double>(1,2);
hope that helps.
remark: didn't test the manual code, but should work. No PerspectiveTransform conversion needed there!
edit: this is the full (tested) code:
// points
std::vector<cv::Point2f> p1;
p1.push_back(cv::Point2f(0,0));
p1.push_back(cv::Point2f(1,0));
p1.push_back(cv::Point2f(0,1));
// simple translation from p1 for testing:
std::vector<cv::Point2f> p2;
p2.push_back(cv::Point2f(1,1));
p2.push_back(cv::Point2f(2,1));
p2.push_back(cv::Point2f(1,2));
cv::Mat R = cv::estimateRigidTransform(p1,p2,false);
// extend rigid transformation to use perspectiveTransform:
cv::Mat H = cv::Mat(3,3,R.type());
H.at<double>(0,0) = R.at<double>(0,0);
H.at<double>(0,1) = R.at<double>(0,1);
H.at<double>(0,2) = R.at<double>(0,2);
H.at<double>(1,0) = R.at<double>(1,0);
H.at<double>(1,1) = R.at<double>(1,1);
H.at<double>(1,2) = R.at<double>(1,2);
H.at<double>(2,0) = 0.0;
H.at<double>(2,1) = 0.0;
H.at<double>(2,2) = 1.0;
// compute perspectiveTransform on p1
std::vector<cv::Point2f> result;
cv::perspectiveTransform(p1,result,H);
for(unsigned int i=0; i<result.size(); ++i)
std::cout << result[i] << std::endl;
which gives output as expected:
[1, 1]
[2, 1]
[1, 2]