Qt VTK real-time point cloud rendering - c++

Question

I am working on real-time point cloud rendering project in Qt Quick and VTK. I have a laser sensor with sampling rate of 200Hz. For testing the program generates random points in while loop using QtConcurrent::Run.
Here is my code:
pointcloud.h
#ifndef POINTCLOUD_H
#define POINTCLOUD_H
#include "QQuickVTKRenderItem.h"
#include "qtconcurrentrun.h"
#include "qtmetamacros.h"
#include "vtkActor.h"
#include "vtkMath.h"
#include "vtkPolyData.h"
#include "vtkPolyDataMapper.h"
#include "vtkSmartPointer.h"
#include <QObject>
#include "vtkDoubleArray.h"
#include "vtkPointData.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkSmartPointerBase.h"
#include <math.h>
#include <QTimer>
#include <QtConcurrent>
class PointCloud : public QObject {
Q_OBJECT
public:
explicit PointCloud(QObject *parent = nullptr);
void setVtkItem(QQuickVTKRenderItem *item);
Q_INVOKABLE void addPoint(const double point[3]);
Q_INVOKABLE void clear();
Q_INVOKABLE void startRandom();
private:
vtkSmartPointer<vtkPolyData> polyData;
vtkSmartPointer<vtkActor> actor;
vtkSmartPointer<vtkPoints> m_points;
vtkSmartPointer<vtkDoubleArray> depth;
vtkSmartPointer<vtkCellArray> vertices;
vtkSmartPointer<vtkPolyDataMapper> mapper;
QQuickVTKRenderItem *m_renderItem;
signals:
};
#endif // POINTCLOUD_H
pointcloud.cpp
#include "pointcloud.h"
#include "vtkProperty.h"
#include "vtkSmartPointer.h"
PointCloud::PointCloud(QObject *parent)
: QObject{parent}{
polyData = vtkSmartPointer<vtkPolyData>::New();
mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
vertices = vtkSmartPointer<vtkCellArray>::New();
depth = vtkSmartPointer<vtkDoubleArray>::New();
depth->SetName("depth");
m_points = vtkSmartPointer<vtkPoints>::New();
polyData->SetPoints(m_points);
polyData->SetVerts(vertices);
polyData->GetPointData()->SetScalars(depth);
polyData->GetPointData()->SetActiveScalars("depth");
mapper->SetInputData(polyData);
mapper->SetColorModeToDefault();
mapper->SetScalarVisibility(1);
actor = vtkSmartPointer<vtkActor>::New();
actor->SetMapper(mapper);
actor->GetProperty()->SetPointSize(2);
}
void PointCloud::setVtkItem(QQuickVTKRenderItem *item) {
m_renderItem = item;
if (m_renderItem) {
m_renderItem->renderer()->AddActor(actor);
}
}
void PointCloud::addPoint(const double point[3]) {
auto pid = m_points->InsertNextPoint(point);
depth->InsertNextTuple1(point[2]);
vertices->InsertNextCell(1);
vertices->InsertCellPoint(pid);
m_points->Modified();
depth->Modified();
vertices->Modified();
}
void PointCloud::clear() {
vertices->Initialize();
vertices->Modified();
depth->Initialize();
depth->Modified();
m_points->Initialize();
m_points->Modified();
}
void PointCloud::startRandom(){
auto future=QtConcurrent::run([&](){
while(polyData->GetPoints()->GetNumberOfPoints()<1000000){
auto theta=2*vtkMath::Pi() *vtkMath::Random();
double phi=acos(2*vtkMath::Random()-1);
double p[3]={sin(phi)*cos(theta),sin(phi)*sin(theta),cos(phi)};
addPoint(p);
Sleep(5);
}
});
}
main.cpp
#include "pointcloud.h"
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQuickVTKRenderItem.h>
#include <QQuickVTKRenderWindow.h>
int main(int argc, char *argv[]) {
QQuickVTKRenderWindow::setupGraphicsBackend();
QGuiApplication app(argc, argv);
PointCloud cloud;
qmlRegisterType<QQuickVTKRenderWindow>("VTKPLUS", 9, 1, "VTKRenderWindow");
qmlRegisterType<QQuickVTKRenderItem>("VTKPLUS", 9, 1, "VTKRenderItem");
qmlRegisterSingletonInstance<PointCloud>("PointCloud", 1, 0, "PointCloud",
&cloud);
QQmlApplicationEngine engine;
const QUrl url(u"qrc:/VTKTest/main.qml"_qs);
QObject::connect(
&engine, &QQmlApplicationEngine::objectCreated, &app,
[url](QObject *obj, const QUrl &objUrl) {
if (!obj && url == objUrl)
QCoreApplication::exit(-1);
},
Qt::QueuedConnection);
engine.load(url);
QObject *rootObject = engine.rootObjects()[0];
auto *container = rootObject->findChild<QObject *>("container");
auto *renderItem = container->findChild<QObject *>("renderItem");
QQuickVTKRenderItem *vtkRenderItem =
dynamic_cast<QQuickVTKRenderItem *>(renderItem);
vtkRenderItem->renderer()->SetBackground(1, 1, 1);
vtkRenderItem->update();
cloud.setVtkItem(vtkRenderItem);
return app.exec();
}
main.qml
import QtQuick
import VTKPLUS
import VTKTest 1.0
import PointCloud
import QtQuick.Controls
import QtQuick.Controls.Material
import QtQuick.Layouts
ApplicationWindow {
visibility: "Maximized"
visible: true
title: "VTK Test"
menuBar: MenuBar {
Menu {
id: fileMenu
title: 'Files'
Action {
text: "Add Point"
onTriggered: {
PointCloud.startRandom()
}
}
Action {
text: "Clear"
onTriggered: {
PointCloud.clear()
}
}
}
}
Item {
anchors.fill: parent
objectName: "container"
VTKRenderWindow {
objectName: "vtkRenderWindow"
id: vtkwindow
anchors.fill: parent
}
VTKRenderItem {
objectName: "renderItem"
anchors.fill: parent
renderWindow: vtkwindow
}
}
}
The code works but when adding new points, the vtk scene updates are very slow.