The post shows how to find 2D convex hull and 3D convex hull from points cloud by VTK.
Here are some points on screen, finally I add a specail point that z value is not 0 for test 3D convex hull.

#include <iostream>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkActor.h>
#include <vtkConeSource.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindowInteractor.h>
#include <QString>
#include <vtkConvexHull2D.h>
#include <vtkDelaunay3D.h>
#include <vtkDataSetSurfaceFilter.h>
#include <vtkCamera.h>

#define vtkSPtr vtkSmartPointer
#define vtkSPtrNew(Var, Type) vtkSPtr<Type> Var = vtkSPtr<Type>::New();

using namespace std;

int main()
{
    vtkSPtrNew( points, vtkPoints );
    points->InsertNextPoint( 0, 0, 0 );
    points->InsertNextPoint( 0, 1, 0 );
    points->InsertNextPoint( 1, 0, 0 );
    points->InsertNextPoint( 1, 1, 0 );
    points->InsertNextPoint( 2, 1, 0 );
    points->InsertNextPoint( 2, 2, 0 );
    points->InsertNextPoint( 1, 2, 0 );

    points->InsertNextPoint( 1, 2, -1 );
    vtkSPtrNew( polyData, vtkPolyData );
    polyData->SetPoints( points );

    // Create the convex hull of the pointcloud
    // ---------------- 2D convex hull -----------------
    vtkSPtrNew( hull2D, vtkConvexHull2D );
    hull2D->SetHullShape( 1 ); //0: BoundingRectangle or 1: ConvexHull.
    hull2D->SetInputData( polyData );
    hull2D->Update();
    vtkSPtrNew( mapper, vtkPolyDataMapper );
    mapper->SetInputData( hull2D->GetOutput() );
    vtkSPtrNew( actor, vtkActor );
    actor->SetMapper( mapper );

    // ---------------- 3D convex hull -----------------
    vtkSmartPointer<vtkDelaunay3D> delaunay = vtkSmartPointer<vtkDelaunay3D>::New();
    delaunay->SetInputData( polyData );
    delaunay->Update();

    vtkSmartPointer<vtkDataSetSurfaceFilter> surfaceFilter = vtkSmartPointer<vtkDataSetSurfaceFilter>::New();
    surfaceFilter->SetInputConnection(delaunay->GetOutputPort());
    surfaceFilter->Update();

    vtkSPtrNew( mapper3D, vtkPolyDataMapper );
    mapper3D->SetInputData( surfaceFilter->GetOutput() );

    vtkSPtrNew( actor3D, vtkActor );
    actor3D->SetMapper( mapper3D );

    // --------------- two renderer -----------------
    vtkSPtrNew( renderWindow, vtkRenderWindow );
    double leftViewport[4] = {0.0, 0.0, 0.5, 1.0};
    double rightViewport[4] = {0.5, 0.0, 1.0, 1.0};

    // Setup both renderers with same camera
    vtkSmartPointer<vtkCamera> camera = vtkSmartPointer<vtkCamera>::New();

    vtkSmartPointer<vtkRenderer> leftRenderer = vtkSmartPointer<vtkRenderer>::New();
    renderWindow->AddRenderer(leftRenderer);
    leftRenderer->SetViewport(leftViewport);
    leftRenderer->SetBackground(.6, .5, .4);
    leftRenderer->SetActiveCamera( camera );
    leftRenderer->AddActor( actor );

    vtkSmartPointer<vtkRenderer> rightRenderer = vtkSmartPointer<vtkRenderer>::New();
    renderWindow->AddRenderer(rightRenderer);
    rightRenderer->SetViewport(rightViewport);
    rightRenderer->SetBackground(.4, .5, .6);
    rightRenderer->SetActiveCamera( camera );
    rightRenderer->AddActor( actor3D );

    renderWindow->AddRenderer( leftRenderer );
    renderWindow->AddRenderer( rightRenderer );
    renderWindow->SetSize( 800, 400 );

    vtkSPtrNew( renderWindowInteractor, vtkRenderWindowInteractor );
    renderWindowInteractor->SetRenderWindow( renderWindow );

    leftRenderer->ResetCamera();
    renderWindow->Render();
    renderWindowInteractor->Start();
    return 0;
}

Categories: VTK

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3D Model Viewer: add grid plane and convex hull.
Add google translate tool at right-bottom position.

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