VtkImageDataToPointCloudFilter.cpp

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// ** INCLUDES **
#include "VtkImageDataToPointCloudFilter.h"
 
#include <vtkDoubleArray.h>
#include <vtkIdList.h>
#include <vtkImageData.h>
#include <vtkInformation.h>
#include <vtkInformationVector.h>
#include <vtkLine.h>
#include <vtkObjectFactory.h>
#include <vtkPointData.h>
#include <vtkPolyData.h>
#include <vtkSmartPointer.h>
 
#include <algorithm>
#include <vector>
 
vtkStandardNewMacro(VtkImageDataToPointCloudFilter);
 
VtkImageDataToPointCloudFilter::VtkImageDataToPointCloudFilter() = default;
 
void VtkImageDataToPointCloudFilter::PrintSelf(ostream& os, vtkIndent indent)
{
    this->Superclass::PrintSelf(os, indent);
}
 
int VtkImageDataToPointCloudFilter::FillInputPortInformation(
    int /*port*/, vtkInformation* info)
{
    info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkImageData");
    return 1;
}
 
int VtkImageDataToPointCloudFilter::RequestData(
    vtkInformation* /*request*/,
    vtkInformationVector** inputVector,
    vtkInformationVector* outputVector)
{
    vtkDebugMacro(<< "Executing VtkImageDataToPointCloudFilter");
 
    vtkInformation* input_info = inputVector[0]->GetInformationObject(0);
    vtkInformation* output_info = outputVector->GetInformationObject(0);
    vtkImageData* input = vtkImageData::SafeDownCast(
        input_info->Get(vtkDataObject::DATA_OBJECT()));
    vtkPolyData* output = vtkPolyData::SafeDownCast(
        output_info->Get(vtkDataObject::DATA_OBJECT()));
 
    if (input->GetScalarSize() != sizeof(float))
    {
        vtkDebugMacro(
            "Existing data does not have float-type and cannot be processed. "
            "Aborting filter process...");
        return 0;
    }
    float* pixvals = static_cast<float*>(input->GetScalarPointer());
    int const n_comp = input->GetNumberOfScalarComponents();
    if (n_comp < 1)
    {
        vtkDebugMacro("Error reading number of components.");
    }
    if (n_comp > 2)
    {
        vtkDebugMacro(
            "RGB colours detected. Using only first channel for computation.");
    }
 
    vtkIdType const n_points = input->GetNumberOfPoints();
    if (n_points == 0)
    {
        vtkDebugMacro("No data found!");
        return -1;
    }
 
    double spacing[3];
    input->GetSpacing(spacing);
 
    if (MinValueRange == -1 || MaxValueRange == -1)
    {
        double range[2];
        vtkPointData* input_data = input->GetPointData();
        input_data->GetArray(0)->GetRange(range);
        MinValueRange = range[0];
        MaxValueRange = range[1];
    }
 
    std::vector<vtkIdType> density;
    density.reserve(n_points);
    for (vtkIdType i = 0; i < n_points; ++i)
    {
        // Skip transparent pixels
        if (n_comp == 2 || n_comp == 4)
        {
            if (pixvals[(i + 1) * n_comp - 1] < 0.00000001f)
            {
                density.push_back(0);
                continue;
            }
        }
        double const val(pixvals[i * n_comp]);
        double const calc_gamma = (IsLinear) ? 1 : Gamma;
        std::size_t const pnts_per_cell =
            interpolate(MinValueRange, MaxValueRange, val, calc_gamma);
        density.push_back(static_cast<vtkIdType>(
            std::floor(pnts_per_cell * GetPointScaleFactor())));
    }
 
    // Allocate the space needed for output objects
    auto const sum =
        std::accumulate(density.begin(), density.end(), vtkIdType{0});
    vtkSmartPointer<vtkPoints> new_points = vtkSmartPointer<vtkPoints>::New();
    new_points->SetNumberOfPoints(sum);
    vtkSmartPointer<vtkCellArray> cells = vtkSmartPointer<vtkCellArray>::New();
    cells->Allocate(sum);
    vtkSmartPointer<vtkDoubleArray> intensity =
        vtkSmartPointer<vtkDoubleArray>::New();
    intensity->Allocate(sum);
    intensity->SetName("Intensity");
    double const half_cellsize(spacing[0] / 2.0);
    std::size_t pnt_idx(0);
    for (std::size_t i = 0; i < static_cast<std::size_t>(n_points); ++i)
    {
        if (density[i] == 0)
        {
            continue;
        }
        double p[3];
        input->GetPoint(i, p);
 
        MathLib::Point3d min_pnt{std::array<double, 3>{
            {p[0] - half_cellsize, p[1] - half_cellsize, MinHeight}}};
        MathLib::Point3d max_pnt{std::array<double, 3>{
            {p[0] + half_cellsize, p[1] + half_cellsize, MaxHeight}}};
        createPoints(new_points, cells, pnt_idx, density[i], min_pnt, max_pnt);
        for (vtkIdType j = 0; j < density[i]; ++j)
        {
            intensity->InsertValue(pnt_idx + j, pixvals[i * n_comp]);
        }
        pnt_idx += density[i];
    }
 
    output->SetPoints(new_points);
    output->SetVerts(cells);
    output->GetPointData()->AddArray(intensity);
    output->GetPointData()->SetActiveAttribute("Intensity",
                                               vtkDataSetAttributes::SCALARS);
    output->Squeeze();
 
    vtkDebugMacro(<< "Created " << new_points->GetNumberOfPoints()
                  << " points.");
    return 1;
}
 
void VtkImageDataToPointCloudFilter::createPoints(
    vtkSmartPointer<vtkPoints>& points,
    vtkSmartPointer<vtkCellArray>& cells,
    std::size_t pnt_idx,
    std::size_t n_points,
    MathLib::Point3d const& min_pnt,
    MathLib::Point3d const& max_pnt) const
{
    for (std::size_t i = 0; i < n_points; ++i)
    {
        double p[3];
        p[0] = getRandomNumber(min_pnt[0], max_pnt[0]);
        p[1] = getRandomNumber(min_pnt[1], max_pnt[1]);
        p[2] = getRandomNumber(min_pnt[2], max_pnt[2]);
        points->SetPoint(pnt_idx + i, p);
        cells->InsertNextCell(1);
        cells->InsertCellPoint(pnt_idx + i);
    }
}
 
double VtkImageDataToPointCloudFilter::getRandomNumber(double const& min,
                                                       double const& max) const
{
    return (static_cast<double>(std::rand()) / RAND_MAX) * (max - min) + min;
}
 
std::size_t VtkImageDataToPointCloudFilter::interpolate(double low,
                                                        double high,
                                                        double p,
                                                        double gamma) const
{
    p = std::clamp(p, low, high);
    double const r = (p - low) / (high - low);
    return static_cast<std::size_t>(
        (MaxNumberOfPointsPerCell - MinNumberOfPointsPerCell) *
            std::pow(r, gamma) +
        MinNumberOfPointsPerCell);
}