平面方程AX+BY+CZ+D=0
变换一下-> A/DX + B/DY+C/DZ= -1
该方程满足Ax=b
其中A为, x为
,b为-1单位阵
求解代码如下:
/* comment
plane equation: Ax + By + Cz + D = 0
convert to: A/D*x + B/D*y + C/D*z = -1
solve: A0*x0 = b0
where A0_i = [x_i, y_i, z_i], x0 = [A/D, B/D, C/D]^T, b0 = [-1, ..., -1]^T
normvec:  normalized x0
*/
template<typename T>
bool esti_normvector(Matrix<T, 3, 1> &normvec, const PointVector &point, const T &threshold, const int &point_num)
{
    MatrixXf A(point_num, 3);
    MatrixXf b(point_num, 1);
    b.setOnes();
    b *= -1.0f;
    for (int j = 0; j < point_num; j++)
    {
        A(j,0) = point[j].x;
        A(j,1) = point[j].y;
        A(j,2) = point[j].z;
    }
    normvec = A.colPivHouseholderQr().solve(b);
    
    for (int j = 0; j < point_num; j++)
    {
        if (fabs(normvec(0) * point[j].x + normvec(1) * point[j].y + normvec(2) * point[j].z + 1.0f) > threshold)
        {
            return false;
        }
    }
    normvec.normalize();
    return true;
}
template<typename T>
bool esti_plane(Matrix<T, 4, 1> &pca_result, const PointVector &point, const T &threshold)
{
    Matrix<T, NUM_MATCH_POINTS, 3> A;
    Matrix<T, NUM_MATCH_POINTS, 1> b;
    b.setOnes();
    b *= -1.0f;
    for (int j = 0; j < NUM_MATCH_POINTS; j++)
    {
        A(j,0) = point[j].x;
        A(j,1) = point[j].y;
        A(j,2) = point[j].z;
    }
    Matrix<T, 3, 1> normvec = A.colPivHouseholderQr().solve(b);
    T n = normvec.norm();
    pca_result(0) = normvec(0) / n;
    pca_result(1) = normvec(1) / n;
    pca_result(2) = normvec(2) / n;
    pca_result(3) = 1.0 / n;
    for (int j = 0; j < NUM_MATCH_POINTS; j++)
    {
        if (fabs(pca_result(0) * point[j].x + pca_result(1) * point[j].y + pca_result(2) * point[j].z + pca_result(3)) > threshold)
        {
            return false;
        }
    }
    // for (int j = 0; j < NUM_MATCH_POINTS; j++)
    // {
    //     if (fabs(normvec(0) * point[j].x + normvec(1) * point[j].y + normvec(2) * point[j].z + 1.0f) > threshold)
    //     {
    //         return false;
    //     }
    // }
    // T n = normvec.norm();
    // pca_result(0) = normvec(0) / n;
    // pca_result(1) = normvec(1) / n;
    // pca_result(2) = normvec(2) / n;
    // pca_result(3) = 1.0 / n; 
    return true;
}


















