C++ 本征：将 Matrix3d 旋转转换为四元数
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Eigen: convert Matrix3d rotation to Quaternion
提问by Esparver
I'm trying to convert a Matrix3drotation to a Quaternion<double>, but I got only weird compiler errors so far. The code I'm using is:
我正在尝试将Matrix3d旋转转换为Quaternion<double>，但到目前为止我只遇到了奇怪的编译器错误。我正在使用的代码是：
Quaternion<double> getQuaternionFromRotationMatrix(const Matrix3d& mat)
{
AngleAxisd aa;
aa = mat;
Quaternion<double> q = aa;// conversion error
return q;
}
And the compiler errors:
和编译器错误：
path/src/Utils.cpp: In function ‘Eigen::Quaternion<double> Utils::getQuaternionFromRotationMatrix(const Matrix3d&)':
path/src/Utils.cpp:55:26: error: conversion from ‘Eigen::AngleAxisd {aka Eigen::AngleAxis<double>}' to non-scalar type ‘Eigen::Quaternion<double>' requested
In file included from /usr/local/include/eigen3/Eigen/Core:283:0,
from /usr/local/include/eigen3/Eigen/Dense:1,
from path/include/Utils.h:4,
from path/src/Utils.cpp:1:
/usr/local/include/eigen3/Eigen/src/Core/Assign.h: In member function ‘Derived& Eigen::DenseBase<Derived>::lazyAssign(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::Matrix<double, 3, 1>, Derived = Eigen::Block<Eigen::Matrix<double, 4, 4>, 4, -0x00000000000000001, true, true>]':
/usr/local/include/eigen3/Eigen/src/Core/Assign.h:534:123: instantiated from ‘static Derived& Eigen::internal::assign_selector<Derived, OtherDerived, false, false>::run(Derived&, const OtherDerived&) [with Derived = Eigen::Block<Eigen::Matrix<double, 4, 4>, 4, -0x00000000000000001, true, true>, OtherDerived = Eigen::Matrix<double, 3, 1>]'
/usr/local/include/eigen3/Eigen/src/Core/Assign.h:574:89: instantiated from ‘Derived& Eigen::MatrixBase<Derived>::operator=(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::Matrix<double, 3, 1>, Derived = Eigen::Block<Eigen::Matrix<double, 4, 4>, 4, -0x00000000000000001, true, true>]'
path/src/Utils.cpp:34:20: instantiated from here
/usr/local/include/eigen3/Eigen/src/Core/Assign.h:504:3: error: static assertion failed: "YOU_MIXED_MATRICES_OF_DIFFERENT_SIZES"
Does someone know how to convert between both representations?
有人知道如何在两种表示之间进行转换吗？
回答by ggael
The constructors from an AngleAxisor Matrixare explicitmeaning you have to write the conversion as follow:
来自AngleAxisor的构造函数Matrix是明确的意思，您必须按如下方式编写转换：
Matrix3f mat;
Quaternionf q(mat);
or
或者
Quaternionf q;
q = mat;
Same for AngleAxis.
对于AngleAxis.
