OpenCV warpperspective

Question

For some reason whenever I use OpenCV\'s warpPerspective() function, the final warped image does not contain everything in the original image. The left part of the image see

Answer 1

this is my solution

since third parameter in "warpPerspective()" is a transformation matrix,

we can make a transformation matrix , which moves the image backward first ,then rotates the image,finally moves the image forward .

In my case,I have a image with height of 160 px and width of 160 px. I want to rotate the image around [80,80] instead of around [0,0]

first,moves the image backward (that means T1)

then rotates the image (that means R)

finally moves the image forward (that means T2)

void rotateImage(Mat &src_img,int degree)
{
float radian=(degree/180.0)*M_PI;
Mat R(3,3,CV_32FC1,Scalar(0));
R.at(0,0)=cos(radian);R.at(0,1)=-sin(radian);
R.at(1,0)=sin(radian);R.at(1,1)=cos(radian);
R.at(2,2)=1;
Mat T1(3,3,CV_32FC1,Scalar(0));
T1.at(0,2)=-80;
T1.at(1,2)=-80;
T1.at(0,0)=1;
T1.at(1,1)=1;
T1.at(2,2)=1;
Mat T2(3,3,CV_32FC1,Scalar(0));
T2.at(0,2)=80;
T2.at(1,2)=80;
T2.at(0,0)=1;
T2.at(1,1)=1;
T2.at(2,2)=1;

std::cerr<