SolvePnPRansac位姿估计算法
SolvePnPRansac是PnP位姿估计鲁棒算法的一种，下面是Opencv 接口函数的描述
/* max 注释
* 函数功能：用ransac的方式求解PnP问题
*
* 参数：
* [in] _opoints 参考点在世界坐标系下的点集；float or double
* [in] _ipoints 参考点在相机像平面的坐标；float or double
* [in] _cameraMatrix 相机内参
* [in] _distCoeffs 相机畸变系数
* [out] _rvec 旋转矩阵
* [out] _tvec 平移向量
* [in] useExtrinsicGuess 若果求解PnP使用迭代算法，初始值可以使用猜测的初始值（true），也可以使用解析求解的结果作为初始值（false）。
* [in] iterationsCount Ransac算法的迭代次数，这只是初始值，根据估计外点的概率，可以进一步缩小迭代次数；（此值函数内部是会不断改变的）,所以一开始可以赋一个大的值。
* [in] reprojectionErrr Ransac筛选内点和外点的距离阈值，这个根据估计内点的概率和每个点的均方差（假设误差按照高斯分布）可以计算出此阈值。
* [in] confidence 此值与计算采样（迭代）次数有关。此值代表从n个样本中取s个点，N次采样可以使s个点全为内点的概率。
* [out] _inliers 返回内点的序列。为矩阵形式
* [in] flags 最小子集的计算模型；
* SOLVEPNP_ITERATIVE(此方案，最小模型用的EPNP，内点选出之后用了一个迭代)；
* SOLVE_P3P(P3P只用在最小模型上，内点选出之后用了一个EPNP)
* SOLVE_AP3P(AP3P只用在最小模型上，内点选出之后用了一个EPNP)
* SOLVE_EPnP(最小模型上&内点选出之后都采用了EPNP)
* 返回值：
* 成功返回true，失败返回false；
*/
bool solvePnPRansac(InputArray _opoints, InputArray _ipoints,
InputArray _cameraMatrix, InputArray _distCoeffs,
OutputArray _rvec, OutputArray _tvec, bool useExtrinsicGuess,
int iterationsCount, float reprojectionError, double confidence,
OutputArray _inliers, int flags)下面是使用例程：
// 自己测试 p3p测位姿算法
#if 1
#include "test_precomp.hpp"
void generate3DPointCloud(std::vector& points, cv::Point3f pmin = cv::Point3f(-1, -1, 5), cv::Point3f pmax = cv::Point3f(1, 1, 10))
{
cv::RNG rng = cv::theRNG(); // fix the seed to use "fixed" input 3D points
for (size_t i = 0; i < points.size(); i++)
{
float _x = rng.uniform(pmin.x, pmax.x);
float _y = rng.uniform(pmin.y, pmax.y);
float _z = rng.uniform(pmin.z, pmax.z);
points[i] = cv::Point3f(_x, _y, _z);
}
}
void generateCameraMatrix(cv::Mat& cameraMatrix, cv::RNG& rng)
{
const double fcMinVal = 1e-3;
const double fcMaxVal = 100;
cameraMatrix.create(3, 3, CV_64FC1);
cameraMatrix.setTo(cv::Scalar(0));
cameraMatrix.at(0, 0) = rng.uniform(fcMinVal, fcMaxVal);
cameraMatrix.at(1, 1) = rng.uniform(fcMinVal, fcMaxVal);
cameraMatrix.at(0, 2) = rng.uniform(fcMinVal, fcMaxVal);
cameraMatrix.at(1, 2) = rng.uniform(fcMinVal, fcMaxVal);
cameraMatrix.at(2, 2) = 1;
}
void generateDistCoeffs(cv::Mat& distCoeffs, cv::RNG& rng)
{
distCoeffs = cv::Mat::zeros(4, 1, CV_64FC1);
for (int i = 0; i < 3; i++)
distCoeffs.at(i, 0) = rng.uniform(0.0, 1.0e-6);
}
void generatePose(cv::Mat& rvec, cv::Mat& tvec, cv::RNG& rng)
{
const double minVal = 1.0e-3;
const double maxVal = 1.0;
rvec.create(3, 1, CV_64FC1);
tvec.create(3, 1, CV_64FC1);
for (int i = 0; i < 3; i++)
{
rvec.at(i, 0) = rng.uniform(minVal, maxVal);
tvec.at(i, 0) = rng.uniform(minVal, maxVal / 10);
}
}
int main_p3p()
{
std::vector points;
points.resize(500);
generate3DPointCloud(points);
std::vector rvecs, tvecs;
cv::Mat trueRvec, trueTvec;
cv::Mat intrinsics, distCoeffs;
generateCameraMatrix(intrinsics, cv::RNG());
generateDistCoeffs(distCoeffs, cv::RNG());
generatePose(trueRvec, trueTvec, cv::RNG());
std::vector opoints;
opoints = std::vector(points.begin(), points.begin() + 3);
std::vector projectedPoints;
projectedPoints.resize(opoints.size());
projectPoints(cv::Mat(opoints), trueRvec, trueTvec, intrinsics, distCoeffs, projectedPoints);
std::cout << "intrinsics: " << intrinsics << std::endl;
std::cout << "distcoeffs: " << distCoeffs << std::endl;
std::cout << "trueRvec: " << trueRvec << std::endl;
std::cout << "trueTvec: " << trueTvec << std::endl;
std::cout << "oPoint: " << opoints << std::endl;
std::cout << "projectedPoints: " << projectedPoints << std::endl;
std::cout<<"result numbers A: :"< points;
points.resize(500);
generate3DPointCloud(points);
std::vector rvecs, tvecs;
cv::Mat trueRvec, trueTvec;
cv::Mat intrinsics, distCoeffs;
generateCameraMatrix(intrinsics, cv::RNG());
generateDistCoeffs(distCoeffs, cv::RNG());
generatePose(trueRvec, trueTvec, cv::RNG());
std::vector opoints;
//opoints = std::vector(points.begin(), points.begin() + 4);
opoints = std::vector(points.begin(), points.end());
std::vector projectedPoints;
projectedPoints.resize(opoints.size());
projectPoints(cv::Mat(opoints), trueRvec, trueTvec, intrinsics, distCoeffs, projectedPoints);
cv::RNG rng = cv::RNG();
for (size_t i = 0; i < projectedPoints.size(); i++)
{
if (i % 100 == 0)
{
projectedPoints[i] = projectedPoints[rng.uniform(0, (int)points.size() - 1)];
}
}
std::cout << "intrinsics: " << intrinsics << std::endl;
std::cout << "distcoeffs: " << distCoeffs << std::endl;
std::cout << "trueRvec: " << trueRvec << std::endl;
std::cout << "trueTvec: " << trueTvec << std::endl;
//std::cout << "oPoint: " << opoints << std::endl;
//std::cout << "projectedPoints: " << projectedPoints << std::endl;
//solveP3P(opoints, projectedPoints, intrinsics, distCoeffs, rvecs, tvecs, cv::SOLVEPNP_AP3P);
cv::Mat rvec, tvec;
solvePnP(opoints, projectedPoints, intrinsics, distCoeffs, rvec, tvec, false,cv::SOLVEPNP_EPNP);
std::cout << rvec <<"---" <