vtk粗配准及其变换
开发环境：
- Windows 11 家庭中文版
- Microsoft Visual Studio Community 2019
- VTK-9.3.0.rc0
- vtk-example
- 参考代码
- 目的：学习与总结
demo解决问题：基于标记点，两个点集在配准后的平均距离最小，要求输入两个点数必须相等，序号一致的点集，做线性变换。
关键类：vtkTransform、vtkTransformFilter、vtkLandmarkTransform
知识点
- vtkMath::Add，此处仅用于创建两个点集合，target、sourse。参考链接
- ShallowCopy：vtk的浅拷贝，共享对象。参考链接
- transform相关的文章两篇：参考链接1、参考链接2 1）
GetMatrix和GetUserMatrix的区别、getTransform和getUserTransform中加User与不加User的区别：不加User是当前actor相对与世界坐标的位置的变化矩阵的get、set；加User是指基于变换中的某一个阶段结果基础上再进行变换的矩阵获取，例如进行了两次变换，第二次变换就是基于第一次的结果基础上变换来的 2）vtkMatrix4x4与vtkTransform的区别: vtkMatrix4x4关注的是矩阵的数学运算（invert、multiply…）、矩阵获取（MatrixFromRotation、缩放与平移矩阵比较好推算）、元素设置（SetElement），重点在于矩阵数据结构本身；vtkTransform重点在于比较直接的视觉操作（缩放scale、旋转rotate、平移translate），多级变换的管理（Concatenate），可以看下官方接口说明：vtkMatrix4x4、vtkTransform - vtkLandmarkTransform：用于粗配准（初步对齐）参考链接 1）AlignFrames(frame2, frame1, transform);//把frame2向frame1靠拢
cpp
landmarkTransform->SetSourceLandmarks(sourcePoints);
landmarkTransform->SetTargetLandmarks(targetPoints)
landmarkTransform->SetModeToRigidBody();
landmarkTransform->Update();2） 获取变换矩阵后传出，给外面的frame2使用
cpp
vtkMatrix4x4* M = landmarkTransform->GetMatrix();
transform->SetMatrix(M);3） 通过显示结果或者输出文件观察线形变换后的位姿
cpp
void ApplyTransform(vtkTransform* transform, std::string filename)
{
vtkNew<vtkPolyData> polydata;
CreatePolydata(polydata);
vtkNew<vtkTransformFilter> transformFilter;
transformFilter->SetInputData(polydata);
transformFilter->SetTransform(transform);
transformFilter->Update();
vtkNew<vtkXMLPolyDataWriter> writer;
writer->SetFileName(filename.c_str());
writer->SetInputConnection(transformFilter->GetOutputPort());
writer->Write();
}cpp
# include <vtkLandmarkTransform.h>
# include <vtkMath.h>
# include <vtkNew.h>
# include <vtkPoints.h>
# include <vtkPolyData.h>
# include <vtkTransform.h>
# include <vtkTransformFilter.h>
# include <vtkVertexGlyphFilter.h>
# include <vtkXMLPolyDataWriter.h>
namespace {
struct Frame
{
Frame(float o[3], float x[3], float y[3], float z[3])
{
this->SetOrigin(o);
this->SetXDirection(x);
this->SetYDirection(y);
this->SetZDirection(z);
std::cout << "Origin: " << this->origin[0] << " " << this->origin[1] << " "
<< this->origin[2] << std::endl;
std::cout << "xDirection: " << this->xDirection[0] << " "
<< this->xDirection[1] << " " << this->xDirection[2] << std::endl;
std::cout << "yDirection: " << this->yDirection[0] << " "
<< this->yDirection[1] << " " << this->yDirection[2] << std::endl;
std::cout << "zDirection: " << this->zDirection[0] << " "
<< this->zDirection[1] << " " << this->zDirection[2] << std::endl;
}
void ApplyTransform(vtkTransform* transform, std::string filename)
{
vtkNew<vtkPolyData> polydata;
CreatePolydata(polydata);
vtkNew<vtkTransformFilter> transformFilter;
transformFilter->SetInputData(polydata);
transformFilter->SetTransform(transform);
transformFilter->Update();
vtkNew<vtkXMLPolyDataWriter> writer;
writer->SetFileName(filename.c_str());
writer->SetInputConnection(transformFilter->GetOutputPort());
writer->Write();
}
void CreatePolydata(vtkPolyData* polydata)
{
/*
* https://blog.csdn.net/liushao1031177/article/details/120809118
static void Add(const float a[3], const float b[3], float c[3]){
for (int i = 0; i < 3; ++i)
{
c[i] = a[i] + b[i];
}
}
*/
vtkNew<vtkPoints> points;
points->InsertNextPoint(this->origin);
float x[3];
vtkMath::Add(this->origin, this->xDirection, x);
points->InsertNextPoint(x);
float y[3];
vtkMath::Add(this->origin, this->yDirection, y);
points->InsertNextPoint(y);
float z[3];
vtkMath::Add(this->origin, this->zDirection, z);
points->InsertNextPoint(z);
polydata->SetPoints(points);
vtkNew<vtkVertexGlyphFilter> vertexGlyphFilter;//单独的点是看不到的，需要转换成符号
vertexGlyphFilter->AddInputData(polydata);
vertexGlyphFilter->Update();
//https://zhuanlan.zhihu.com/p/138080564
polydata->ShallowCopy(vertexGlyphFilter->GetOutput());
}
void Write(std::string filename)
{
vtkNew<vtkPolyData> polydata;
CreatePolydata(polydata);
vtkNew<vtkXMLPolyDataWriter> writer;
writer->SetFileName(filename.c_str());
writer->SetInputData(polydata);
writer->Write();
}
float origin[3];
float xDirection[3];
float yDirection[3];
float zDirection[3];
void SetOrigin(float o[3])
{
this->origin[0] = o[0];
this->origin[1] = o[1];
this->origin[2] = o[2];
}
void SetXDirection(float direction[3])
{
vtkMath::Normalize(direction);
this->xDirection[0] = direction[0];
this->xDirection[1] = direction[1];
this->xDirection[2] = direction[2];
}
void SetYDirection(float direction[3])
{
vtkMath::Normalize(direction);
this->yDirection[0] = direction[0];
this->yDirection[1] = direction[1];
this->yDirection[2] = direction[2];
}
void SetZDirection(float direction[3])
{
vtkMath::Normalize(direction);
this->zDirection[0] = direction[0];
this->zDirection[1] = direction[1];
this->zDirection[2] = direction[2];
}
};
void AlignFrames(Frame sourceFrame, Frame destinationFrame,
vtkTransform* transform);
} // namespace
int main(int, char*[])
{
//工程应用中，此处frame中构造的点可在renderViewer中进行点拾取后记录
float frame1origin[3] = {0, 0, 0};
float frame1XDirection[3] = {1, 0, 0};
float frame1YDirection[3] = {0, 1, 0};
std::cout << frame1YDirection[0] << " " << frame1YDirection[1] << " "
<< frame1YDirection[2] << std::endl;
float frame1ZDirection[3] = {0, 0, 1};
Frame frame1(frame1origin, frame1XDirection, frame1YDirection,
frame1ZDirection);
frame1.Write("frame1.vtp");
float frame2origin[3] = {0, 0, 0};
float frame2XDirection[3] = {.707f, .707f, 0};
float frame2YDirection[3] = {-.707f, .707f, 0};
float frame2ZDirection[3] = {0, 0, 1};
Frame frame2(frame2origin, frame2XDirection, frame2YDirection,
frame2ZDirection);
frame2.Write("frame2.vtp");
vtkNew<vtkTransform> transform;
AlignFrames(frame2, frame1, transform); // Brings frame2 to frame1
// std::cout << *transform << std::endl;
frame2.ApplyTransform(transform, "transformed.vtp");
return EXIT_SUCCESS;
}
namespace {
void AlignFrames(Frame sourceFrame, Frame targetFrame, vtkTransform* transform)
{
//https://blog.csdn.net/q610098308/article/details/125362653
// This function takes two frames and finds the matrix M between them.
//两个点集在配准后的平均距离最小，要求输入两个点数必须相等，序号一致的点集，做线性变换。它常用于粗略匹配，效率高。
vtkNew<vtkLandmarkTransform> landmarkTransform;
// Setup source points
vtkNew<vtkPoints> sourcePoints;
sourcePoints->InsertNextPoint(sourceFrame.origin);
float sourceX[3];
vtkMath::Add(sourceFrame.origin, sourceFrame.xDirection, sourceX);
sourcePoints->InsertNextPoint(sourceX);
float sourceY[3];
vtkMath::Add(sourceFrame.origin, sourceFrame.yDirection, sourceY);
sourcePoints->InsertNextPoint(sourceY);
float sourceZ[3];
vtkMath::Add(sourceFrame.origin, sourceFrame.zDirection, sourceZ);
sourcePoints->InsertNextPoint(sourceZ);
// Setup target points
vtkNew<vtkPoints> targetPoints;
targetPoints->InsertNextPoint(targetFrame.origin);
float targetX[3];
vtkMath::Add(targetFrame.origin, targetFrame.xDirection, targetX);
targetPoints->InsertNextPoint(targetX);
float targetY[3];
vtkMath::Add(targetFrame.origin, targetFrame.yDirection, targetY);
targetPoints->InsertNextPoint(targetY);
float targetZ[3];
vtkMath::Add(targetFrame.origin, targetFrame.zDirection, targetZ);
targetPoints->InsertNextPoint(targetZ);
landmarkTransform->SetSourceLandmarks(sourcePoints);
landmarkTransform->SetTargetLandmarks(targetPoints);
landmarkTransform->SetModeToRigidBody();
landmarkTransform->Update();
vtkMatrix4x4* M = landmarkTransform->GetMatrix();
transform->SetMatrix(M);
}
} // namespace