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     40 //M*/
     41 #include "precomp.hpp"
     42 
     43 namespace cv
     44 {
     45 
     46 KalmanFilter::KalmanFilter() {}
     47 KalmanFilter::KalmanFilter(int dynamParams, int measureParams, int controlParams, int type)
     48 {
     49     init(dynamParams, measureParams, controlParams, type);
     50 }
     51 
     52 void KalmanFilter::init(int DP, int MP, int CP, int type)
     53 {
     54     CV_Assert( DP > 0 && MP > 0 );
     55     CV_Assert( type == CV_32F || type == CV_64F );
     56     CP = std::max(CP, 0);
     57 
     58     statePre = Mat::zeros(DP, 1, type);
     59     statePost = Mat::zeros(DP, 1, type);
     60     transitionMatrix = Mat::eye(DP, DP, type);
     61 
     62     processNoiseCov = Mat::eye(DP, DP, type);
     63     measurementMatrix = Mat::zeros(MP, DP, type);
     64     measurementNoiseCov = Mat::eye(MP, MP, type);
     65 
     66     errorCovPre = Mat::zeros(DP, DP, type);
     67     errorCovPost = Mat::zeros(DP, DP, type);
     68     gain = Mat::zeros(DP, MP, type);
     69 
     70     if( CP > 0 )
     71         controlMatrix = Mat::zeros(DP, CP, type);
     72     else
     73         controlMatrix.release();
     74 
     75     temp1.create(DP, DP, type);
     76     temp2.create(MP, DP, type);
     77     temp3.create(MP, MP, type);
     78     temp4.create(MP, DP, type);
     79     temp5.create(MP, 1, type);
     80 }
     81 
     82 const Mat& KalmanFilter::predict(const Mat& control)
     83 {
     84     // update the state: x'(k) = A*x(k)
     85     statePre = transitionMatrix*statePost;
     86 
     87     if( !control.empty() )
     88         // x'(k) = x'(k) + B*u(k)
     89         statePre += controlMatrix*control;
     90 
     91     // update error covariance matrices: temp1 = A*P(k)
     92     temp1 = transitionMatrix*errorCovPost;
     93 
     94     // P'(k) = temp1*At + Q
     95     gemm(temp1, transitionMatrix, 1, processNoiseCov, 1, errorCovPre, GEMM_2_T);
     96 
     97     // handle the case when there will be measurement before the next predict.
     98     statePre.copyTo(statePost);
     99     errorCovPre.copyTo(errorCovPost);
    100 
    101     return statePre;
    102 }
    103 
    104 const Mat& KalmanFilter::correct(const Mat& measurement)
    105 {
    106     // temp2 = H*P'(k)
    107     temp2 = measurementMatrix * errorCovPre;
    108 
    109     // temp3 = temp2*Ht + R
    110     gemm(temp2, measurementMatrix, 1, measurementNoiseCov, 1, temp3, GEMM_2_T);
    111 
    112     // temp4 = inv(temp3)*temp2 = Kt(k)
    113     solve(temp3, temp2, temp4, DECOMP_SVD);
    114 
    115     // K(k)
    116     gain = temp4.t();
    117 
    118     // temp5 = z(k) - H*x'(k)
    119     temp5 = measurement - measurementMatrix*statePre;
    120 
    121     // x(k) = x'(k) + K(k)*temp5
    122     statePost = statePre + gain*temp5;
    123 
    124     // P(k) = P'(k) - K(k)*temp2
    125     errorCovPost = errorCovPre - gain*temp2;
    126 
    127     return statePost;
    128 }
    129 
    130 }
    131