标签：插件 qPCA checked Eigen compare ccPC rotatedPoint PCA axis

在上一节 https://blog.csdn.net/csy1021/article/details/141200135

我们已经完成了具体开发前的准备工作，包括各级 CMakelists.txt 的设置，相关内容的修改，并已成功编译

如需整个插件项目，编译后的 dll，或其他帮助，欢迎留言、私信或加群【群号：392784757】

这一节针对我们的 qPCA 插件，引入进阶内容，包括第三方库引入、设置用户输入参数界面以及具体逻辑的编写

最终整体的 qPCA 插件目录结构如下

第三方库引入

由于 cc 处理的主要是点云、网格数据，较少涉及到大型矩阵的求解，而 PCA 分析需要去计算矩阵，在这里我们要引入第三方库 Eigen 帮助完成

Eigen 是一个轻量级的 C++ 数学库，主要用于矩阵和线性代数运算。它的一个优势就是它是头文件库，不需要编译成库文件，引入难度也会低一点

在这里使用的是 Eigen 3.4 版本官方网站 https://eigen.tuxfamily.org/index.php?title=Main_Page

下载解压后在 extern 目录下

具体路径形式 extern\eigen3\Eigen\**

然后修改当前 qPCA 插件的最高 CMakeLists.txt

添加内容

include_directories("${CMAKE_CURRENT_LIST_DIR}/extern/eigen3") # 设置包含目录

我在这里设置后发现并不能成功引入

同时还在 include 文件夹下的 CMakeLists.txt 添加

include_directories("${CMAKE_CURRENT_LIST_DIR}/../extern/eigen3")

【最终版本 qPCA 插件的最高 CMakeLists.txt 如下】

# CloudCompare example for standard plugins

option( PLUGIN_qPCA "Install PCA plugin" OFF )

if ( PLUGIN_qPCA )
	project( QPCA_PLUGIN )

	AddPlugin( NAME ${PROJECT_NAME} )

	add_subdirectory( include )
	add_subdirectory( src )
	add_subdirectory( ui )
	include_directories("${CMAKE_CURRENT_LIST_DIR}/extern/eigen3")
	# set dependencies to necessary libraries
	# target_link_libraries( ${PROJECT_NAME} LIB1 )
endif()

【最终版本 include 文件夹下的 CMakeLists.txt 如下】

include_directories("${CMAKE_CURRENT_LIST_DIR}/../extern/eigen3")

target_sources( ${PROJECT_NAME}
	PRIVATE
		#${CMAKE_CURRENT_LIST_DIR}/ActionA.h
		${CMAKE_CURRENT_LIST_DIR}/qPCA.h
		${CMAKE_CURRENT_LIST_DIR}/ccPCADlg.h
)

target_include_directories( ${PROJECT_NAME}
	PRIVATE
		${CMAKE_CURRENT_SOURCE_DIR}
)

插件基于 ExamplePlugin 而来，其中的 ActionA.h，ActionA.cpp 并未删除相关内容被注释，不会引入到我们的插件中

然后 cmake 重新构建项目，测试是否引入成功

在 qPCA.h 中添加

#include <Eigen/Core>

在 qPCA.cpp 中添加相关头文件，看能否找到

#include <Eigen/Core>
#include <Eigen/Eigenvalues>
#include <Eigen/Dense>

在 vs 中 ctrl 然后点击引入的头文件，引入成功可以看到具体的头文件，否则就未引入成功

ui 用户参数设置接收框

针对 qPCA 插件我设置的用户参数是主方向和哪个坐标轴对齐，界面展示如下

可以对齐到不同的轴上，在最开始开发时，可以不引入用户参数接收框，程序基本完成后，再引入 ui，提升用户体验

按照真实的开发情况，这一小节应放在最后，但放在中间行文也可以

ui 的设计

【略】

根据自己的插件设置不同的布局和对应输入组件，可基于 CC 已有的进行修改

结束后应由有一个 ui 文件，在本文是 ui/pcaDlg.ui

ui 文件夹下 cmakelists.txt 最终版如下

target_sources( ${PROJECT_NAME}
	PRIVATE
		${CMAKE_CURRENT_LIST_DIR}/pcaDlg.ui
)

其实也可以由代码来写界面，不需要.ui ，也就是.ui 编译后的 ui_xxx.h 头文件，这里是 qt 的知识了

ui 代码层面引入

新建 include/ccPCADlg.h，src/ccPCADlg.cpp

cmakelists.txt 修改

qPCA 插件的最高 CMakeLists.txt 已在上文摆出

include 文件下 cmakelists.txt 已在上文摆出

src 文件夹下 cmakelists.txt 最终版如下

target_sources( ${PROJECT_NAME}
	PRIVATE
		# ${CMAKE_CURRENT_LIST_DIR}/ActionA.cpp
		${CMAKE_CURRENT_LIST_DIR}/qPCA.cpp
		${CMAKE_CURRENT_LIST_DIR}/ccPCADlg.cpp
)

ccPCADlg.h

#ifndef CC_PCA_DLG_HEADER
#define CC_PCA_DLG_HEADER

#include "ui_pcaDlg.h"

class ccPCADlg : public QDialog, public Ui::PCADialog
{
	Q_OBJECT

public:

	//! Default constructor
	explicit ccPCADlg(QWidget* parent = nullptr);


protected:

	//! Saves (temporarily) the dialog parameters on acceptation
	void saveSettings();

};

#endif

这里 ccPCADlg 会继承 ui 文件编译后 ui_pcaDlg.h 中的 Ui::PCADialog，声明的 ccPCADlg 可以拿到界面上的所有组件，进而可以获取用户设置的值

ccPCADlg.cpp

#include "ccPCADlg.h"
#include <QButtonGroup>


static bool axis_x_checeked  = true;
static bool axis_y_checeked = false;
static bool axis_z_checeked = false;

ccPCADlg::ccPCADlg(QWidget* parent)
	: QDialog(parent)
	, Ui::PCADialog()
{
	setupUi(this);

	connect(buttonBox, &QDialogButtonBox::accepted, this, &ccPCADlg::saveSettings);
	// 创建一个 QButtonGroup 逻辑上保证只有一个被选中
	QButtonGroup* buttonGroup = new QButtonGroup(this);
	buttonGroup->addButton(radioButton);
	buttonGroup->addButton(radioButton_2);
	buttonGroup->addButton(radioButton_3);
	radioButton->setChecked(true); // default x
}


void ccPCADlg::saveSettings()
{
	axis_x_checeked = radioButton->isChecked();
	axis_y_checeked = radioButton_2->isChecked();
	axis_z_checeked = radioButton_3->isChecked();
}

主程序逻辑

qPCA.h

#pragma once

#include "ccStdPluginInterface.h"
#include <Eigen/Core>

class qPCA : public QObject, public ccStdPluginInterface
{
	Q_OBJECT
	Q_INTERFACES(ccPluginInterface ccStdPluginInterface)
	Q_PLUGIN_METADATA(IID "cccorp.cloudcompare.plugin.qPCA" FILE "../info.json")

public:
	explicit qPCA(QObject *parent = nullptr);
	~qPCA() override = default;

	// Inherited from ccStdPluginInterface
	void onNewSelection(const ccHObject::Container &selectedEntities) override;
	QList<QAction *> getActions() override;
	ccHObject* executePCA(ccPointCloud* ccPC,
		Eigen::Vector3f& eigenValuesPCA,
		Eigen::Matrix3f& eigenVectorsPCA,
		Eigen::Vector3f& pcaCentroid,
		bool silent);
protected:
	void doAction();
private:
	QAction *m_action;
};

其中

ccHObject* executePCA(ccPointCloud* ccPC,
		Eigen::Vector3f& eigenValuesPCA,
		Eigen::Matrix3f& eigenVectorsPCA,
		Eigen::Vector3f& pcaCentroid,
		bool silent);

是我们的核心函数

qPCA.cpp

一一实现对应的函数

声明用于插件的 cc 提供的程序接口，暴露出来给后面函数使用

static ccMainAppInterface* s_app = nullptr;

构造函数

qPCA::qPCA( QObject *parent )
	: QObject( parent )
	, ccStdPluginInterface( ":/CC/plugin/qPCA/info.json" )
	, m_action( nullptr )
{
	s_app = m_app; // m_app 继承自 ccStdPluginInterface 接口 也是 ccMainAppInterface*
}

onNewSelection()

void qPCA::onNewSelection( const ccHObject::Container &selectedEntities )
{
	if (m_action)
		m_action->setEnabled(selectedEntities.size() == 1 && selectedEntities[0]->isA(CC_TYPES::POINT_CLOUD));

}

保证选到了一个实体，且是点云

getActions()

QList<QAction *> qPCA::getActions()
{
	// default action (if it has not been already created, this is the moment to do it)
	if ( !m_action )
	{
		// Here we use the default plugin name, description, and icon,
		// but each action should have its own.
		m_action = new QAction( getName(), this );
		m_action->setToolTip( getDescription() );
		m_action->setIcon( getIcon() );

		// Connect appropriate signal
		connect( m_action, &QAction::triggered, this, &qPCA::doAction);
	}

	return { m_action };
}

我们只有一个 action ，保持不变；

如需添加更多子功能 action 啥的，需要在这里链接对应信号和槽函数

doAction()

执行核心逻辑前的检查和准备，包括实体检查和判断，获取用户设置值，实体类型转换为点云，核心函数的准备

static bool axis_x_checked = true;
static bool axis_y_checked = false;
static bool axis_z_checked = false;
void qPCA::doAction()
{
	assert(m_app);
	if (!m_app)
		return;
	m_app->dispToConsole("[qPCA] welcome use PCA plugin by xxx!", ccMainAppInterface::STD_CONSOLE_MESSAGE);
	QMessageBox::information(nullptr, "info", "welcome use PCA plugin");

	const ccHObject::Container& selectedEntities = m_app->getSelectedEntities();
	size_t selNum = selectedEntities.size();
	if (selNum != 1)
	{
		ccLog::Error("[qPCA] Select only one cloud!");
		return;
	}

	ccHObject* ent = selectedEntities[0];
	assert(ent);
	if (!ent || !ent->isA(CC_TYPES::POINT_CLOUD))
	{
		ccLog::Error("[qPCA] Select a real point cloud!");
		return;
	}

	ccPointCloud* pc = static_cast<ccPointCloud*>(ent);

	// input cloud
	CCVector3 bbMin, bbMax;
	pc->getBoundingBox(bbMin, bbMax);
	/*CCVector3 diff = bbMax - bbMin;
	float scale = std::max(std::max(diff[0], diff[1]), diff[2]);*/

	ccPCADlg pcaDlg(m_app->getMainWindow());
	if (!pcaDlg.exec())
	{
		return;
	}
	axis_x_checked = pcaDlg.radioButton->isChecked();
	axis_y_checked = pcaDlg.radioButton_2->isChecked();
	axis_z_checked = pcaDlg.radioButton_3->isChecked();


	Eigen::Vector3f eigenValuesPCA;
	Eigen::Matrix3f eigenVectorsPCA;
	Eigen::Vector3f pcaCentroid;
	ccHObject* group = executePCA(pc,eigenValuesPCA,eigenVectorsPCA, pcaCentroid,false);

	if (group)
	{
		m_app->addToDB(group);
		m_app->refreshAll();
	}
}

executePCA()

主要逻辑为

计算点云中心---> 计算点云协方差矩阵 ---> Eigen 求解奇异值和奇异向量 ---> 构建旋转矩阵 ---》旋转变换到标准坐标系，主方向与根据用户选择的轴对齐，默认 x 轴

ccHObject* qPCA::executePCA(ccPointCloud* ccPC,
	Eigen::Vector3f& eigenValuesPCA,
	Eigen::Matrix3f& eigenVectorsPCA,
	Eigen::Vector3f& pcaCentroid,
	bool silent)
{
	ccHObject* group = nullptr;
	const CCVector3d& globalShift = ccPC->getGlobalShift();
	double globalScale = ccPC->getGlobalScale();

	auto toEigen = [](const CCVector3* vec) {
		return Eigen::Vector3f(vec->x, vec->y, vec->z);
	};
	pcaCentroid.setZero();
	for (unsigned i = 0; i < ccPC->size(); ++i)
	{
		const CCVector3* point = ccPC->getPoint(i);
		Eigen::Vector3f eigenPoint(point->x, point->y, point->z);
		pcaCentroid += eigenPoint;
	}
	pcaCentroid /= static_cast<float>(ccPC->size());

	Eigen::Matrix3f covarianceMatrix = Eigen::Matrix3f::Zero();
	for (unsigned i = 0; i < ccPC->size(); ++i)
	{
		Eigen::Vector3f diff = (toEigen(ccPC->getPoint(i))) - pcaCentroid;
		covarianceMatrix += diff * diff.transpose();
	}
	covarianceMatrix /= static_cast<float>(ccPC->size());

	// 进行 PCA：求解特征值和特征向量
	Eigen::SelfAdjointEigenSolver<Eigen::Matrix3f> solver(covarianceMatrix);
	eigenValuesPCA = solver.eigenvalues();   // 返回特征值
	eigenVectorsPCA = solver.eigenvectors(); // 返回特征向量

	// log
	Eigen::IOFormat CleanFmt(4, 0, ", ", "\n", "[", "]");
	std::stringstream vectorStream, matrixStream;
	vectorStream << pcaCentroid.format(CleanFmt);
	m_app->dispToConsole("[qPCA] pca center", ccMainAppInterface::STD_CONSOLE_MESSAGE);
	m_app->dispToConsole(QString::fromStdString(vectorStream.str()), ccMainAppInterface::STD_CONSOLE_MESSAGE);

	vectorStream.str("");
	m_app->dispToConsole("[qPCA] eigen values", ccMainAppInterface::STD_CONSOLE_MESSAGE);
	vectorStream << eigenValuesPCA.format(CleanFmt);
	matrixStream << eigenVectorsPCA.format(CleanFmt);

	m_app->dispToConsole(QString::fromStdString(vectorStream.str()), ccMainAppInterface::STD_CONSOLE_MESSAGE);
	m_app->dispToConsole("[qPCA] eigen vectors sorted by eigen value in descending order", ccMainAppInterface::STD_CONSOLE_MESSAGE);
	m_app->dispToConsole(QString::fromStdString(matrixStream.str()), ccMainAppInterface::STD_CONSOLE_MESSAGE);
	//m_app->forceConsoleDisplay();

	// 将点云主方向转换到 x y z 轴上
	char axis = axis_y_checked ? 'y' : (axis_z_checked ? 'z' : 'x');
	m_app->dispToConsole(QString::fromStdString("[qPCA] frist component 2 axis "+std::tolower(axis)), ccMainAppInterface::STD_CONSOLE_MESSAGE);
	//char axis = 'x'; //通过对话框获取 默认
	Eigen::Matrix4f rotationMatrix = Eigen::Matrix4f::Identity();
	Eigen::Matrix3f tmp;
	switch (axis)
	{
	case 'x':
		rotationMatrix.block<3, 3>(0, 0) = eigenVectorsPCA.transpose(); // x y z
		break;
	case 'y':
		tmp = eigenVectorsPCA;
		tmp.col(0).swap(tmp.col(1));
		rotationMatrix.block<3, 3>(0, 0) = tmp.transpose(); // y x z
		break;
	case 'z':
		tmp = eigenVectorsPCA;
		tmp.col(0).swap(tmp.col(2));
		rotationMatrix.block<3, 3>(0, 0) = tmp.transpose(); // z x y
		break;
	default:
		break;
	}
	matrixStream.str("");
	matrixStream << rotationMatrix.format(CleanFmt);
	m_app->dispToConsole(QString::fromStdString(matrixStream.str()), ccMainAppInterface::STD_CONSOLE_MESSAGE);

	rotationMatrix.block<3, 1>(0, 3) = -1.0f * ((axis_x_checked ? eigenVectorsPCA.transpose() : tmp.transpose()) * pcaCentroid);

	matrixStream.str("");
	matrixStream << rotationMatrix.format(CleanFmt);
	m_app->dispToConsole(QString::fromStdString(matrixStream.str()), ccMainAppInterface::STD_CONSOLE_MESSAGE);

	ccPointCloud* firstComponent = new ccPointCloud(
		QString("first  component - projecting to (%1) plane ").arg((axis_y_checked ? "xz" : (axis_z_checked ? "xy" : "yz")))
	);
	ccPointCloud* secondComponent = new ccPointCloud(
		QString("second component - projecting to (%1) plane ").arg((axis_y_checked ? "yz" : (axis_z_checked ? "zy" : "xz")))
	);
	ccPointCloud* thirdComponent = new ccPointCloud(
		QString("third  component - projecting to (%1) plane ").arg((axis_y_checked ? "yx" : (axis_z_checked ? "zx" : "xy")))
	); // 主成分

	ccPointCloud* stdAxisCloud = new ccPointCloud("2stdAxisCloud");

	if (!firstComponent->reserve(static_cast<unsigned>(ccPC->size())))
	{
		ccLog::Error("[qPCA] Not enough memory!");
		delete firstComponent;
		return nullptr;
	}
	if (!secondComponent->reserve(static_cast<unsigned>(ccPC->size())))
	{
		ccLog::Error("[qPCA] Not enough memory!");
		delete secondComponent;
		return nullptr;
	}
	if (!thirdComponent->reserve(static_cast<unsigned>(ccPC->size())))
	{
		ccLog::Error("[qPCA] Not enough memory!");
		delete thirdComponent;
		return nullptr;
	}
	if (!stdAxisCloud->reserve(static_cast<unsigned>(ccPC->size())))
	{
		ccLog::Error("[qPCA] Not enough memory!");
		delete stdAxisCloud;
		return nullptr;
	}

	// 遍历每个点并应用旋转矩阵
	std::stringstream pointStream;
	for (unsigned i = 0; i < ccPC->size(); ++i)
	{
		pointStream.str("");
		CCVector3* point = const_cast<CCVector3*>(ccPC->getPoint(i));

		// 将 CCVector3 转换为 Eigen::Vector3f
		Eigen::Vector4f eigenPoint(point->x, point->y, point->z, 1.0f);

		// 旋转点
		Eigen::Vector4f rotatedPoint = rotationMatrix * eigenPoint;

		// 将结果写回 CCVector3,// 还是不写回了
		/*point->x = rotatedPoint.x();
		point->y = rotatedPoint.y();
		point->z = rotatedPoint.z();*/
		//pointStream << point->x << "," << point->y << "," << point->z;
		//m_app->dispToConsole(QString::fromStdString(pointStream.str()), ccMainAppInterface::STD_CONSOLE_MESSAGE);

		stdAxisCloud->addPoint({ rotatedPoint[0],rotatedPoint[1],rotatedPoint[2] });

		if (axis_y_checked) // align to y // y x z
		{
			firstComponent->addPoint({ rotatedPoint[0],0.0f,rotatedPoint[2] });
			secondComponent->addPoint({ 0.0f,rotatedPoint[1],rotatedPoint[2] });
			thirdComponent->addPoint({ rotatedPoint[0],rotatedPoint[1],0.0f });
		}
		else if (axis_x_checked) // align to x // x y z
		{
			firstComponent->addPoint({ 0.0f,rotatedPoint[1],rotatedPoint[2] });
			secondComponent->addPoint({ rotatedPoint[0],0.0f,rotatedPoint[2] });
			thirdComponent->addPoint({ rotatedPoint[0],rotatedPoint[1],0.0f });
		}
		else if(axis_z_checked) // align to  z // z x y
		{
			firstComponent->addPoint({ rotatedPoint[0],rotatedPoint[1],0.0f });
			secondComponent->addPoint({ 0.0f,rotatedPoint[1],rotatedPoint[2] });
			thirdComponent->addPoint({ rotatedPoint[0],0.0f,rotatedPoint[2] });
		}
		else
		{
			ccLog::Error("[qPCA] axis error");
			return nullptr;
		}


	}
	// 更新点云
	//ccPC->invalidateBoundingBox();
	//ccPC->setVisible(false);

	// 设置 主成分 颜色 可视化
	for (auto pcShape : { stdAxisCloud ,firstComponent,secondComponent,thirdComponent })
	{
		ccColor::Rgb col = ccColor::Generator::Random();
		pcShape->setColor(col);
		pcShape->showSF(false);
		pcShape->showColors(true);
		pcShape->showNormals(true);
		pcShape->setVisible(true);
	}


	// 计算投影 各个方向 主成分 已经变换到标准坐标系下, 直接坐标赋0
	//ccPointCloud firstComponent, secondComponent, thirdComponent; // 合并到上面的循环完成
	if (!group)
	{
		group = new ccHObject(QString("PCA processed - align to %1 axis (%2)").arg((axis_y_checked?"y":(axis_z_checked?"z":"x")), ccPC->getName()));
	}
	if (group)
	{
		group->addChild(stdAxisCloud);
		group->addChild(firstComponent);
		group->addChild(secondComponent);
		group->addChild(thirdComponent);
	}


	return group;
}

至此所有内容都完成

cmake 重新构建、然后编译

效果展示

感谢免费 GIF 压缩 - 专研免费“GIF 压缩”在线工具 (gifcompress.com) 提供的免费 gif 压缩服务

cc-PCA

下一篇，我们一起学习一下 cc 的代码。