VTK 顯示大量點云數據及交互（點云拾取、著色、測量等）功能

????????VTK (Visualization Toolkit) 是一個強大的開源可視化庫，非常適合處理點云數據。下面將介紹如何使用 VTK 顯示大量點云數據，并實現點云拾取、著色、測量等功能。

基本點云顯示

創建一個基本的點云顯示程序：

cpp

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkVertexGlyphFilter.h>int main() {// 創建點云數據vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();// 添加大量點（這里示例添加100萬個隨機點）for (int i = 0; i < 1000000; ++i) {points->InsertNextPoint((double)rand() / RAND_MAX * 100.0,(double)rand() / RAND_MAX * 100.0,(double)rand() / RAND_MAX * 100.0);}// 創建PolyData對象并設置點vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();polydata->SetPoints(points);// 使用VertexGlyphFilter將點轉換為可渲染的頂點vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter = vtkSmartPointer<vtkVertexGlyphFilter>::New();glyphFilter->SetInputData(polydata);glyphFilter->Update();// 創建mapper和actorvtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();mapper->SetInputConnection(glyphFilter->GetOutputPort());vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();actor->SetMapper(mapper);actor->GetProperty()->SetPointSize(2); // 設置點大小// 創建渲染器、渲染窗口和交互器vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();renderWindow->AddRenderer(renderer);vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New();renderWindowInteractor->SetRenderWindow(renderWindow);// 添加actor到渲染器renderer->AddActor(actor);renderer->SetBackground(0.1, 0.2, 0.4); // 設置背景顏色// 開始渲染renderWindow->Render();renderWindowInteractor->Start();return 0;
}

點云拾取功能

要實現點云拾取，可以使用 VTK 的點拾取器 (vtkPointPicker):

cpp

#include <vtkPointPicker.h>// 在main函數中創建交互器后添加以下代碼// 創建點拾取器
vtkSmartPointer<vtkPointPicker> pointPicker = vtkSmartPointer<vtkPointPicker>::New();
renderWindowInteractor->SetPicker(pointPicker);// 添加觀察者處理拾取事件
vtkSmartPointer<vtkCallbackCommand> pickCallback = vtkSmartPointer<vtkCallbackCommand>::New();
pickCallback->SetCallback([](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkRenderWindowInteractor* interactor = static_cast<vtkRenderWindowInteractor*>(caller);vtkPointPicker* picker = static_cast<vtkPointPicker*>(interactor->GetPicker());int x = interactor->GetEventPosition()[0];int y = interactor->GetEventPosition()[1];picker->Pick(x, y, 0, interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer());vtkIdType pointId = picker->GetPointId();if (pointId != -1) {double* pos = picker->GetPickPosition();std::cout << "Picked point ID: " << pointId << std::endl;std::cout << "Position: (" << pos[0] << ", " << pos[1] << ", " << pos[2] << ")" << std::endl;}
});renderWindowInteractor->AddObserver(vtkCommand::LeftButtonPressEvent, pickCallback);

點云著色功能

可以為點云添加顏色屬性，實現著色效果：

cpp

#include <vtkUnsignedCharArray.h>// 在創建點數據后添加顏色數組
vtkSmartPointer<vtkUnsignedCharArray> colors = vtkSmartPointer<vtkUnsignedCharArray>::New();
colors->SetNumberOfComponents(3); // RGB
colors->SetName("Colors");// 為每個點添加隨機顏色
for (int i = 0; i < points->GetNumberOfPoints(); ++i) {unsigned char color[3] = {static_cast<unsigned char>(rand() % 256),static_cast<unsigned char>(rand() % 256),static_cast<unsigned char>(rand() % 256)};colors->InsertNextTypedTuple(color);
}polydata->GetPointData()->SetScalars(colors);// 然后修改mapper以使用這些顏色
mapper->SetScalarVisibility(1); // 啟用標量顏色
mapper->SetScalarModeToUsePointData(); // 使用點數據中的標量

點云測量功能

1. 點對點距離測量

首先實現最基本的點對點距離測量功能：

#include <vtkDistanceWidget.h>
#include <vtkDistanceRepresentation3D.h>
#include <vtkSphereSource.h>// 在main函數中創建交互器后添加以下代碼// 創建距離測量工具
vtkSmartPointer<vtkDistanceWidget> distanceWidget = vtkSmartPointer<vtkDistanceWidget>::New();
distanceWidget->SetInteractor(renderWindowInteractor);
distanceWidget->CreateDefaultRepresentation();// 設置距離表示的樣式
vtkDistanceRepresentation3D* distanceRep = vtkDistanceRepresentation3D::SafeDownCast(distanceWidget->GetRepresentation());
distanceRep->SetLabelFormat("%-#6.3g mm"); // 設置顯示格式
distanceRep->GetAxisProperty()->SetColor(1, 0, 0); // 設置軸線顏色
distanceRep->GetAxisProperty()->SetLineWidth(2); // 設置線寬// 添加標記球體
vtkSmartPointer<vtkSphereSource> sphere1 = vtkSmartPointer<vtkSphereSource>::New();
sphere1->SetRadius(1.0);
vtkSmartPointer<vtkSphereSource> sphere2 = vtkSmartPointer<vtkSphereSource>::New();
sphere2->SetRadius(1.0);distanceRep->SetPoint1Representation(sphere1->GetOutput());
distanceRep->SetPoint2Representation(sphere2->GetOutput());// 啟用距離測量工具
distanceWidget->On();

2. 多點距離測量（折線測量）

如果需要測量多點間的累計距離，可以實現折線測量：

#include <vtkContourWidget.h>
#include <vtkOrientedGlyphContourRepresentation.h>
#include <vtkPolygonalSurfacePointPlacer.h>// 創建折線測量工具
vtkSmartPointer<vtkContourWidget> contourWidget = vtkSmartPointer<vtkContourWidget>::New();
contourWidget->SetInteractor(renderWindowInteractor);
contourWidget->ContinuousDrawOn(); // 啟用連續繪制// 設置表示方式
vtkOrientedGlyphContourRepresentation* contourRep = vtkOrientedGlyphContourRepresentation::SafeDownCast(contourWidget->GetRepresentation());
contourRep->GetLinesProperty()->SetColor(0, 1, 0); // 設置線顏色
contourRep->GetLinesProperty()->SetLineWidth(2); // 設置線寬// 設置點放置器，使點吸附到點云上
vtkSmartPointer<vtkPolygonalSurfacePointPlacer> pointPlacer = vtkSmartPointer<vtkPolygonalSurfacePointPlacer>::New();
pointPlacer->AddProp(actor);
pointPlacer->GetPolys()->AddItem(polydata);
contourRep->SetPointPlacer(pointPlacer);// 添加回調函數計算總長度
vtkSmartPointer<vtkCallbackCommand> contourCallback = vtkSmartPointer<vtkCallbackCommand>::New();
contourCallback->SetCallback([](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkContourWidget* widget = static_cast<vtkContourWidget*>(caller);vtkContourRepresentation* rep = widget->GetContourRepresentation();int numPoints = rep->GetNumberOfNodes();if (numPoints > 1) {double totalLength = 0.0;double pos1[3], pos2[3];rep->GetNthNodeWorldPosition(0, pos1);for (int i = 1; i < numPoints; ++i) {rep->GetNthNodeWorldPosition(i, pos2);totalLength += sqrt(vtkMath::Distance2BetweenPoints(pos1, pos2));memcpy(pos1, pos2, 3 * sizeof(double));}std::cout << "Total length: " << totalLength << " mm" << std::endl;}
});contourWidget->AddObserver(vtkCommand::InteractionEvent, contourCallback);
contourWidget->On();

3. 面積測量（多邊形區域）

對于閉合區域的面積測量：

#include <vtkPolygon.h>
#include <vtkCellArray.h>// 修改contourWidget的回調函數以支持面積計算
contourCallback->SetCallback([](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkContourWidget* widget = static_cast<vtkContourWidget*>(caller);vtkContourRepresentation* rep = widget->GetContourRepresentation();int numPoints = rep->GetNumberOfNodes();if (numPoints > 2) {// 計算周長double totalLength = 0.0;double pos1[3], pos2[3];rep->GetNthNodeWorldPosition(0, pos1);for (int i = 1; i < numPoints; ++i) {rep->GetNthNodeWorldPosition(i, pos2);totalLength += sqrt(vtkMath::Distance2BetweenPoints(pos1, pos2));memcpy(pos1, pos2, 3 * sizeof(double));}// 閉合路徑rep->GetNthNodeWorldPosition(0, pos2);totalLength += sqrt(vtkMath::Distance2BetweenPoints(pos1, pos2));// 計算面積vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();for (int i = 0; i < numPoints; ++i) {rep->GetNthNodeWorldPosition(i, pos1);points->InsertNextPoint(pos1);}vtkSmartPointer<vtkPolygon> polygon = vtkSmartPointer<vtkPolygon>::New();polygon->Initialize(numPoints, points->GetPoints(), points->GetBounds());double area = polygon->ComputeArea();std::cout << "Perimeter: " << totalLength << " mm" << std::endl;std::cout << "Area: " << area << " mm2" << std::endl;}
});

4. 點云高度差測量

對于三維點云，可以測量高度差：

// 在點拾取回調中添加高度差計算
pickCallback->SetCallback([](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {static double lastPos[3] = {0, 0, 0};static bool firstPick = true;vtkRenderWindowInteractor* interactor = static_cast<vtkRenderWindowInteractor*>(caller);vtkPointPicker* picker = static_cast<vtkPointPicker*>(interactor->GetPicker());int x = interactor->GetEventPosition()[0];int y = interactor->GetEventPosition()[1];picker->Pick(x, y, 0, interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer());vtkIdType pointId = picker->GetPointId();if (pointId != -1) {double* pos = picker->GetPickPosition();std::cout << "Picked point ID: " << pointId << std::endl;std::cout << "Position: (" << pos[0] << ", " << pos[1] << ", " << pos[2] << ")" << std::endl;if (!firstPick) {double distance = sqrt(vtkMath::Distance2BetweenPoints(pos, lastPos));double heightDiff = fabs(pos[2] - lastPos[2]);std::cout << "Distance from last point: " << distance << " mm" << std::endl;std::cout << "Height difference: " << heightDiff << " mm" << std::endl;}memcpy(lastPos, pos, 3 * sizeof(double));firstPick = false;}
});

5. 測量結果顯示在3D視圖

將測量結果直接顯示在3D視圖上：

#include <vtkTextActor.h>
#include <vtkTextProperty.h>// 創建文本actor用于顯示測量結果
vtkSmartPointer<vtkTextActor> textActor = vtkSmartPointer<vtkTextActor>::New();
textActor->SetPosition(10, 10);
textActor->GetTextProperty()->SetFontSize(18);
textActor->GetTextProperty()->SetColor(1.0, 1.0, 1.0);
renderer->AddActor2D(textActor);// 修改距離測量的回調函數
distanceWidget->AddObserver(vtkCommand::InteractionEvent, [textActor](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkDistanceWidget* widget = static_cast<vtkDistanceWidget*>(caller);vtkDistanceRepresentation3D* rep = vtkDistanceRepresentation3D::SafeDownCast(widget->GetRepresentation());double distance = rep->GetDistance();std::stringstream ss;ss << "Distance: " << std::fixed << std::setprecision(2) << distance << " mm";textActor->SetInput(ss.str().c_str());
});

6. 測量工具切換

添加鍵盤控制來切換不同的測量工具：

// 添加鍵盤回調
vtkSmartPointer<vtkCallbackCommand> keyCallback = vtkSmartPointer<vtkCallbackCommand>::New();
keyCallback->SetCallback([](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkRenderWindowInteractor* interactor = static_cast<vtkRenderWindowInteractor*>(caller);std::string key = interactor->GetKeySym();static vtkDistanceWidget* distanceWidget = static_cast<vtkDistanceWidget*>(clientData);static vtkContourWidget* contourWidget = static_cast<vtkContourWidget*>(clientData);if (key == "d") {// 切換距離測量distanceWidget->SetEnabled(!distanceWidget->GetEnabled());contourWidget->SetEnabled(false);} else if (key == "c") {// 切換輪廓測量contourWidget->SetEnabled(!contourWidget->GetEnabled());distanceWidget->SetEnabled(false);} else if (key == "a") {// 切換面積測量bool enabled = contourWidget->GetEnabled();contourWidget->SetEnabled(!enabled);distanceWidget->SetEnabled(false);if (enabled) {contourWidget->CloseLoop();}}
});renderWindowInteractor->AddObserver(vtkCommand::KeyPressEvent, keyCallback);

性能優化

對于大量點云數據，可以考慮以下優化措施：

1、使用vtkOctreePointLocator?加速點查找

#include <vtkOctreePointLocator.h>vtkSmartPointer<vtkOctreePointLocator> pointLocator = vtkSmartPointer<vtkOctreePointLocator>::New();
pointLocator->SetDataSet(polydata);
pointLocator->BuildLocator();// 拾取時使用locator查找最近點
double searchPoint[3] = {x, y, z};
vtkIdType pointId = pointLocator->FindClosestPoint(searchPoint);

2、使用點云簡化?減少顯示點數

#include <vtkQuadricClustering.h>vtkSmartPointer<vtkQuadricClustering> decimate = vtkSmartPointer<vtkQuadricClustering>::New();
decimate->SetInputData(polydata);
decimate->SetNumberOfDivisions(50, 50, 50); // 調整簡化程度
decimate->Update();

3、使用GPU加速

#include <vtkGPUInfo.h>
#include <vtkGPUInfoList.h>// 檢查GPU信息
vtkSmartPointer<vtkGPUInfoList> infoList = vtkSmartPointer<vtkGPUInfoList>::New();
infoList->Probe();if (infoList->GetNumberOfGPUs() > 0) {mapper->SetUseHardwareShading(true);
}

完整示例

完整示例1（點云顯示+點云拾取+點云著色）

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkVertexGlyphFilter.h>
#include <vtkUnsignedCharArray.h>
#include <vtkPointPicker.h>
#include <vtkCallbackCommand.h>
#include <vtkOctreePointLocator.h>
#include <iostream>int main() {// 創建點云數據vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();// 添加10萬個隨機點for (int i = 0; i < 100000; ++i) {points->InsertNextPoint((double)rand() / RAND_MAX * 100.0,(double)rand() / RAND_MAX * 100.0,(double)rand() / RAND_MAX * 100.0);}// 創建顏色數組vtkSmartPointer<vtkUnsignedCharArray> colors = vtkSmartPointer<vtkUnsignedCharArray>::New();colors->SetNumberOfComponents(3);colors->SetName("Colors");for (int i = 0; i < points->GetNumberOfPoints(); ++i) {unsigned char color[3] = {static_cast<unsigned char>(rand() % 256),static_cast<unsigned char>(rand() % 256),static_cast<unsigned char>(rand() % 256)};colors->InsertNextTypedTuple(color);}// 創建PolyData對象vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();polydata->SetPoints(points);polydata->GetPointData()->SetScalars(colors);// 創建點定位器（用于加速拾取）vtkSmartPointer<vtkOctreePointLocator> pointLocator = vtkSmartPointer<vtkOctreePointLocator>::New();pointLocator->SetDataSet(polydata);pointLocator->BuildLocator();// 將點轉換為可渲染的頂點vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter = vtkSmartPointer<vtkVertexGlyphFilter>::New();glyphFilter->SetInputData(polydata);glyphFilter->Update();// 創建mapper和actorvtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();mapper->SetInputConnection(glyphFilter->GetOutputPort());mapper->SetScalarVisibility(1);mapper->SetScalarModeToUsePointData();vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();actor->SetMapper(mapper);actor->GetProperty()->SetPointSize(3);// 創建渲染器和窗口vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();renderWindow->AddRenderer(renderer);renderWindow->SetSize(800, 600);vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New();renderWindowInteractor->SetRenderWindow(renderWindow);// 設置點拾取器vtkSmartPointer<vtkPointPicker> pointPicker = vtkSmartPointer<vtkPointPicker>::New();renderWindowInteractor->SetPicker(pointPicker);// 添加拾取回調vtkSmartPointer<vtkCallbackCommand> pickCallback = vtkSmartPointer<vtkCallbackCommand>::New();pickCallback->SetCallback([](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkRenderWindowInteractor* interactor = static_cast<vtkRenderWindowInteractor*>(caller);int x = interactor->GetEventPosition()[0];int y = interactor->GetEventPosition()[1];interactor->GetPicker()->Pick(x, y, 0, interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer());vtkPointPicker* picker = static_cast<vtkPointPicker*>(interactor->GetPicker());vtkIdType pointId = picker->GetPointId();if (pointId != -1) {double* pos = picker->GetPickPosition();std::cout << "Picked point ID: " << pointId << std::endl;std::cout << "Position: (" << pos[0] << ", " << pos[1] << ", " << pos[2] << ")" << std::endl;// 高亮顯示選中的點（例如改變顏色）// 這里可以添加代碼修改選中點的顏色}});renderWindowInteractor->AddObserver(vtkCommand::LeftButtonPressEvent, pickCallback);// 添加actor到渲染器renderer->AddActor(actor);renderer->SetBackground(0.1, 0.2, 0.4);// 開始渲染renderWindow->Render();renderWindowInteractor->Start();return 0;
}

完整示例2（點云測量）

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkVertexGlyphFilter.h>
#include <vtkUnsignedCharArray.h>
#include <vtkPointPicker.h>
#include <vtkCallbackCommand.h>
#include <vtkDistanceWidget.h>
#include <vtkDistanceRepresentation3D.h>
#include <vtkSphereSource.h>
#include <vtkContourWidget.h>
#include <vtkOrientedGlyphContourRepresentation.h>
#include <vtkPolygonalSurfacePointPlacer.h>
#include <vtkTextActor.h>
#include <vtkTextProperty.h>
#include <vtkMath.h>
#include <iostream>
#include <sstream>
#include <iomanip>int main() {// 創建點云數據vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();// 添加隨機點for (int i = 0; i < 50000; ++i) {points->InsertNextPoint((double)rand() / RAND_MAX * 100.0,(double)rand() / RAND_MAX * 100.0,(double)rand() / RAND_MAX * 20.0); // Z軸范圍小一些，便于觀察高度差}// 創建顏色數組vtkSmartPointer<vtkUnsignedCharArray> colors = vtkSmartPointer<vtkUnsignedCharArray>::New();colors->SetNumberOfComponents(3);colors->SetName("Colors");for (int i = 0; i < points->GetNumberOfPoints(); ++i) {unsigned char color[3] = {static_cast<unsigned char>(rand() % 256),static_cast<unsigned char>(rand() % 256),static_cast<unsigned char>(rand() % 256)};colors->InsertNextTypedTuple(color);}// 創建PolyData對象vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();polydata->SetPoints(points);polydata->GetPointData()->SetScalars(colors);// 將點轉換為可渲染的頂點vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter = vtkSmartPointer<vtkVertexGlyphFilter>::New();glyphFilter->SetInputData(polydata);glyphFilter->Update();// 創建mapper和actorvtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();mapper->SetInputConnection(glyphFilter->GetOutputPort());mapper->SetScalarVisibility(1);mapper->SetScalarModeToUsePointData();vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();actor->SetMapper(mapper);actor->GetProperty()->SetPointSize(3);// 創建渲染器和窗口vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();renderWindow->AddRenderer(renderer);renderWindow->SetSize(800, 600);vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New();renderWindowInteractor->SetRenderWindow(renderWindow);// 設置點拾取器vtkSmartPointer<vtkPointPicker> pointPicker = vtkSmartPointer<vtkPointPicker>::New();renderWindowInteractor->SetPicker(pointPicker);// 創建文本actor用于顯示測量結果vtkSmartPointer<vtkTextActor> textActor = vtkSmartPointer<vtkTextActor>::New();textActor->SetPosition(10, 10);textActor->GetTextProperty()->SetFontSize(18);textActor->GetTextProperty()->SetColor(1.0, 1.0, 1.0);renderer->AddActor2D(textActor);// 創建距離測量工具vtkSmartPointer<vtkDistanceWidget> distanceWidget = vtkSmartPointer<vtkDistanceWidget>::New();distanceWidget->SetInteractor(renderWindowInteractor);distanceWidget->CreateDefaultRepresentation();vtkDistanceRepresentation3D* distanceRep = vtkDistanceRepresentation3D::SafeDownCast(distanceWidget->GetRepresentation());distanceRep->SetLabelFormat("%-#6.3g mm");distanceRep->GetAxisProperty()->SetColor(1, 0, 0);distanceRep->GetAxisProperty()->SetLineWidth(2);vtkSmartPointer<vtkSphereSource> sphere1 = vtkSmartPointer<vtkSphereSource>::New();sphere1->SetRadius(1.0);vtkSmartPointer<vtkSphereSource> sphere2 = vtkSmartPointer<vtkSphereSource>::New();sphere2->SetRadius(1.0);distanceRep->SetPoint1Representation(sphere1->GetOutput());distanceRep->SetPoint2Representation(sphere2->GetOutput());distanceWidget->AddObserver(vtkCommand::InteractionEvent, [textActor](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkDistanceWidget* widget = static_cast<vtkDistanceWidget*>(caller);vtkDistanceRepresentation3D* rep = vtkDistanceRepresentation3D::SafeDownCast(widget->GetRepresentation());double distance = rep->GetDistance();std::stringstream ss;ss << "Distance: " << std::fixed << std::setprecision(2) << distance << " mm";textActor->SetInput(ss.str().c_str());});// 創建輪廓測量工具vtkSmartPointer<vtkContourWidget> contourWidget = vtkSmartPointer<vtkContourWidget>::New();contourWidget->SetInteractor(renderWindowInteractor);contourWidget->ContinuousDrawOn();vtkOrientedGlyphContourRepresentation* contourRep = vtkOrientedGlyphContourRepresentation::SafeDownCast(contourWidget->GetRepresentation());contourRep->GetLinesProperty()->SetColor(0, 1, 0);contourRep->GetLinesProperty()->SetLineWidth(2);vtkSmartPointer<vtkPolygonalSurfacePointPlacer> pointPlacer = vtkSmartPointer<vtkPolygonalSurfacePointPlacer>::New();pointPlacer->AddProp(actor);pointPlacer->GetPolys()->AddItem(polydata);contourRep->SetPointPlacer(pointPlacer);contourWidget->AddObserver(vtkCommand::InteractionEvent, [textActor](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkContourWidget* widget = static_cast<vtkContourWidget*>(caller);vtkContourRepresentation* rep = widget->GetContourRepresentation();int numPoints = rep->GetNumberOfNodes();if (numPoints > 1) {// 計算周長double totalLength = 0.0;double pos1[3], pos2[3];rep->GetNthNodeWorldPosition(0, pos1);for (int i = 1; i < numPoints; ++i) {rep->GetNthNodeWorldPosition(i, pos2);totalLength += sqrt(vtkMath::Distance2BetweenPoints(pos1, pos2));memcpy(pos1, pos2, 3 * sizeof(double));}std::stringstream ss;ss << "Perimeter: " << std::fixed << std::setprecision(2) << totalLength << " mm";// 如果閉合，計算面積if (numPoints > 2 && rep->IsClosed()) {vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();for (int i = 0; i < numPoints; ++i) {rep->GetNthNodeWorldPosition(i, pos1);points->InsertNextPoint(pos1);}vtkSmartPointer<vtkPolygon> polygon = vtkSmartPointer<vtkPolygon>::New();polygon->Initialize(numPoints, points->GetPoints(), points->GetBounds());double area = polygon->ComputeArea();ss << "\nArea: " << std::fixed << std::setprecision(2) << area << " mm2";}textActor->SetInput(ss.str().c_str());}});// 添加鍵盤控制vtkSmartPointer<vtkCallbackCommand> keyCallback = vtkSmartPointer<vtkCallbackCommand>::New();keyCallback->SetCallback([distanceWidget, contourWidget, textActor](vtkObject* caller, unsigned long eventId, void* clientData, void* callData) {vtkRenderWindowInteractor* interactor = static_cast<vtkRenderWindowInteractor*>(caller);std::string key = interactor->GetKeySym();if (key == "d" || key == "D") {// 切換距離測量distanceWidget->SetEnabled(!distanceWidget->GetEnabled());contourWidget->SetEnabled(false);textActor->SetInput("Distance measurement mode (click two points)");} else if (key == "c" || key == "C") {// 切換輪廓測量contourWidget->SetEnabled(!contourWidget->GetEnabled());distanceWidget->SetEnabled(false);textActor->SetInput("Contour measurement mode (click multiple points)");} else if (key == "a" || key == "A") {// 切換面積測量bool enabled = !contourWidget->GetEnabled();contourWidget->SetEnabled(enabled);distanceWidget->SetEnabled(false);if (enabled) {textActor->SetInput("Area measurement mode (click points to close loop)");contourWidget->CloseLoop();}} else if (key == "Escape") {// 退出所有測量模式distanceWidget->SetEnabled(false);contourWidget->SetEnabled(false);textActor->SetInput("");}});renderWindowInteractor->AddObserver(vtkCommand::KeyPressEvent, keyCallback);// 添加actor到渲染器renderer->AddActor(actor);renderer->SetBackground(0.1, 0.2, 0.4);// 開始渲染renderWindow->Render();// 顯示操作提示std::cout << "Measurement Controls:" << std::endl;std::cout << "  D - Toggle distance measurement" << std::endl;std::cout << "  C - Toggle contour measurement" << std::endl;std::cout << "  A - Toggle area measurement" << std::endl;std::cout << "  ESC - Exit measurement mode" << std::endl;renderWindowInteractor->Start();return 0;
}

功能說明

  1. 距離測量：按 'D' 鍵激活，點擊兩個點測量它們之間的距離

  2. 輪廓測量：按 'C' 鍵激活，點擊多個點測量折線總長度

  3. 面積測量：按 'A' 鍵激活，點擊多個點后閉合區域測量面積

  4. 結果顯示：測量結果實時顯示在3D視圖左上角

  5. 退出測量：按 ESC 鍵退出所有測量模式

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