InterpolateCamera

VTKExamples/Cxx/Rendering/InterpolateCamera

Description¶

This example uses vtkCameraInterpolator to generate a smooth interpolation between camera views. The key points for the cameras' positions are generated from the vtkPolyData's bounding box. The cameras' focal points are at the center of the polydata.

The key points are computed from the corners of the bounding box. They are pushed out along a vector from the center to the corner point. The amount of pushing is a random multiplier of the range of the data.

Question

Code¶

InterpolateCamera.cxx

#include <vtkCameraInterpolator.h>
#include <vtkSmartPointer.h>

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkNamedColors.h>
#include <vtkPoints.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

#include <vtkSphereSource.h>

#include <vtksys/SystemTools.hxx>

#include <array>
#include <chrono>
#include <iterator>
#include <vector>
#include <random>

template <class T, std::size_t N>
ostream &operator<<(ostream &o, const std::array<T, N> &arr)
{
copy(arr.cbegin(), arr.cend(), std::ostream_iterator<T>(o, ", "));
return o;
}

template <class T, std::size_t N>
ostream &operator<<(ostream &o, const std::vector<T> &vec)
{
copy(vec.cbegin(), vec.cend(), std::ostream_iterator<T>(o, ", "));
return o;
}

namespace
{

void ComputeKeyPoints(vtkPolyData *polyData, std::array<double, 3> &center,
std::vector<std::array<double, 3>> &keyPoints);
}

int main(int argc, char *argv[]) {

vtkSmartPointer<vtkNamedColors> colors =
vtkSmartPointer<vtkNamedColors>::New();

vtkSmartPointer<vtkPolyData> polyData = ReadPolyData(argc > 1 ? argv[1] : "");

// Setup camera views for interpolation
vtkSmartPointer<vtkCameraInterpolator> interpolator =
vtkSmartPointer<vtkCameraInterpolator>::New();
interpolator->SetInterpolationTypeToSpline();

std::array<double, 3> center;
std::vector<std::array<double, 3>> keyPoints;
ComputeKeyPoints(polyData, center, keyPoints);

for (size_t i = 0; i < keyPoints.size() + 1; ++i) {
auto j = i;
vtkSmartPointer<vtkCamera> cam =
vtkSmartPointer<vtkCamera>::New();
cam->SetFocalPoint(center.data());
if (i < keyPoints.size())
{
cam->SetPosition(keyPoints[i].data());
}
else
{
cam->SetPosition(keyPoints[0].data());
}
cam->SetViewUp(0.0, 0.0, 1.0);
}

// Visualize
vtkSmartPointer<vtkPolyDataMapper> mapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
mapper->SetInputData(polyData);
mapper->ScalarVisibilityOff();

vtkSmartPointer<vtkProperty> backProp =
vtkSmartPointer<vtkProperty>::New();
backProp->SetDiffuseColor(colors->GetColor3d("Banana").GetData());
backProp->SetDiffuse(.76);
backProp->SetSpecular(.4);
backProp->SetSpecularPower(30);
;

vtkSmartPointer<vtkActor> actor =
vtkSmartPointer<vtkActor>::New();
actor->SetMapper(mapper);
actor->SetBackfaceProperty(backProp);
actor->GetProperty()->SetDiffuseColor(
colors->GetColor3d("Crimson").GetData());
actor->GetProperty()->SetSpecular(.6);
actor->GetProperty()->SetSpecularPower(30);

vtkSmartPointer<vtkRenderer> renderer =
vtkSmartPointer<vtkRenderer>::New();
vtkSmartPointer<vtkRenderWindow> renderWindow =
vtkSmartPointer<vtkRenderWindow>::New();
renderWindow->SetSize(640, 480);

vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
renderWindowInteractor->SetRenderWindow(renderWindow);

renderer->SetBackground(colors->GetColor3d("Silver").GetData());

vtkSmartPointer<vtkCamera> camera =
vtkSmartPointer<vtkCamera>::New();
renderer->SetActiveCamera(camera);

auto numSteps = 600;
auto minT = interpolator->GetMinimumT();
auto maxT = interpolator->GetMaximumT();
for (auto i = 0; i < numSteps; ++i)
{
double t = (double)i * (maxT - minT) / (double)(numSteps - 1);
interpolator->InterpolateCamera(t, camera);
renderer->ResetCameraClippingRange();
renderWindow->Render();
}

renderWindowInteractor->Start();

return EXIT_SUCCESS;
}

namespace
{
{
vtkSmartPointer<vtkPolyData> polyData;
std::string extension =
vtksys::SystemTools::GetFilenameLastExtension(std::string(fileName));
if (extension == ".ply")
{
}
else if (extension == ".vtp")
{
}
else if (extension == ".obj")
{
}
else if (extension == ".stl")
{
}
else if (extension == ".vtk")
{
}
else if (extension == ".g") {
}
else
{
vtkSmartPointer<vtkSphereSource> source =
vtkSmartPointer<vtkSphereSource>::New();
source->Update();
polyData = source->GetOutput();
}
return polyData;
}

void ComputeKeyPoints(vtkPolyData *polyData, std::array<double, 3> &center,
std::vector<std::array<double, 3>> &keyPoints)
{
std::mt19937 mt(4355412); //Standard mersenne_twister_engine
std::uniform_real_distribution<double> dis(1.0, 3.0);

// Get Bounding Box
std::array<double, 6> bounds;
polyData->GetBounds(bounds.data());

double range;
range = std::max(std::max(bounds[1] - bounds[0], bounds[3] - bounds[2]),
bounds[5] - bounds[3]);

std::vector<std::array<double, 3>> points(8);
std::array<double, 3> point;
point = {{bounds[0], bounds[2], bounds[4]}};
points[0] = point;

point = {{bounds[1], bounds[2], bounds[4]}};
points[1] = point;

point = {{bounds[1], bounds[2], bounds[5]}};
points[2] = point;

point = {{bounds[0], bounds[2], bounds[5]}};
points[3] = point;

point = {{bounds[0], bounds[3], bounds[4]}};
points[4] = point;

point = {{bounds[1], bounds[3], bounds[4]}};
points[5] = point;

point = {{bounds[1], bounds[3], bounds[5]}};
points[6] = point;

point = {{bounds[0], bounds[3], bounds[5]}};
points[7] = point;

polyData->GetCenter(center.data());

for (size_t i = 0; i < points.size(); ++i)
{
std::array<double, 3> direction;
for (auto j = 0; j < 3; ++j)
{
direction[j] = points[i][j] - center[j];
}
vtkMath::Normalize(direction.data());
double factor = dis(mt);
keyPoints.resize(8);
for (auto j = 0; j < 3; ++j)
{
keyPoints[i][j] = points[i][j] + direction[j] * range * factor;
}
}
}
} // namespace


CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(InterpolateCamera)

find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkIOGeometry
vtkIOLegacy
vtkIOPLY
vtkIOXML
vtkInteractionStyle
vtkRenderingContextOpenGL2
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingGL2PSOpenGL2
vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
message("Skipping InterpolateCamera: ${VTK_NOT_FOUND_MESSAGE}") return () endif() message (STATUS "VTK_VERSION:${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
include(${VTK_USE_FILE}) add_executable(InterpolateCamera MACOSX_BUNDLE InterpolateCamera.cxx ) target_link_libraries(InterpolateCamera PRIVATE${VTK_LIBRARIES})
else ()
# include all components
target_link_libraries(InterpolateCamera PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS InterpolateCamera MODULES${VTK_LIBRARIES}
)
endif ()


cd InterpolateCamera/build


If VTK is installed:

cmake ..


If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..


Build the project:

make


and run it:

./InterpolateCamera


WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.