用VTK读取三维点云图并显示的程序遇到有关问题，求帮助

用VTK读取三维点云图并显示的程序遇到问题，求帮助
该程序是读取txt里的三维点云数据然后显示出来
程序如下：

#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkPoints.h"
#include "vtkUnsignedCharArray.h"
#include "vtkCamera.h"
#include "vtkPolyVertex.h"
#include "vtkUnstructuredGrid.h"
#include "vtkDataSetMapper.h"
#include "vtkCellLinks.h"
#include "vector"
#include "cstdlib"
#include "stdlib.h"
//#include "stdafx.h"
#include "string"  
#include "string.h"
#include "vtkPolyDataMapper.h"
#include "vtkActor.h"
#include "vtkProperty.h"
#include "iostream"
#include "fstream"

using namespace std;

int main()
{
  vtkRenderer *ren = vtkRenderer::New();
   
  vtkPoints *points = vtkPoints::New();
   

  vtkUnsignedCharArray *Colors = vtkUnsignedCharArray :: New();
  unsigned char Color[] = { 0, 0, 0 };
   
  vector<unsigned char> *oColors = new vector<unsigned char>;
  string line;
  int iPts = 0;
  double x = 0, y = 0, z = 0;
  int iStart = 0, iEnd = 0;
   

  ifstream fin("D:\\VTKstudy\\vtkpoint1\\bin\\leaf2.txt");
  if(!fin){
  cout << "Unable to open myfile";
  exit(1); // terminate with error

}

  string str;
  while(getline(fin,str)){ //一行一行地读,直到失败为止
   
  iEnd = str.find_first_of(' ', iStart );
  line.assign(str,iStart, iEnd - iStart);
  x= atof(line.c_str());
  iStart = iEnd + 1;
  iEnd = str.find_first_of(' ', iStart );
  line.assign(str,iStart, iEnd - iStart);
  y= atof(line.c_str());//strncpy(char_num,str+2+k,3);
  iStart = iEnd + 1;

  iEnd = str.find_first_of(' ', iStart );
  line.assign(str,iStart, iEnd - iStart);
  z= atof(line.c_str());
  points->InsertNextPoint(x, y, z);

  iStart = iEnd + 1;
  iEnd = str.find_first_of(' ', iStart );
  line.assign(str,iStart, iEnd - iStart);
  Color[0]= reinterpret_cast<unsigned char>(line.c_str());
  oColors->push_back(Color[0]);

  iStart = iEnd + 1;
  iEnd = str.find_first_of(' ', iStart );
  line.assign(str,iStart, iEnd - iStart);
  Color[1]= reinterpret_cast<unsigned char>(line.c_str());
  oColors->push_back(Color[1]);
  iStart = iEnd + 1;
  iEnd = str.find_first_of(' ', iStart );
  line.assign(str,iStart, iEnd - iStart);
  Color[2]= reinterpret_cast<unsigned char>(line.c_str());
   
  oColors->push_back(Color[2]);
  iStart = 0;

  iPts++;  
  }
  return 0;



  vtkPolyVertex *polyvertex =vtkPolyVertex ::New();
  polyvertex->GetPointIds()->SetNumberOfIds(iPts);
   
   
  for(int i = 0; i < iPts; i++)
  {
  polyvertex->GetPointIds()->SetId(i, i);
  }

  vtkUnstructuredGrid * grid = vtkUnstructuredGrid:: New();
  grid->SetPoints(points);
  grid->InsertNextCell(polyvertex->GetCellType(),polyvertex->GetPointIds());

  vtkDataSetMapper *map1 = vtkDataSetMapper :: New();
  map1->SetInput(grid);

  map1->SetColorModeToDefault();
  map1->SetScalarModeToUsePointFieldData();

  map1->SelectColorArray("colors");


   
  vtkActor *actor1 = vtkActor:: New();
  actor1->SetMapper(map1);
  actor1->GetProperty()->SetColor(0.2, 0.5, 0.75);

  vtkCamera *camera = vtkCamera::New();
  camera->SetPosition(5.0,0.0,0.0);
  camera->SetFocalPoint(-1.0,0.0,0.0);
  camera->SetViewUp(0.0,1.0,0.0);
  ren->SetActiveCamera(camera);

vtkRenderWindow *renWin = vtkRenderWindow::New();

  renWin->AddRenderer(ren);
  renWin->SetSize( 300, 300 );  
  vtkRenderWindowInteractor *iRen = vtkRenderWindowInteractor::New();
  iRen->SetRenderWindow(renWin);  
   
  ren->AddActor(actor1);
  ren->SetBackground(1, 1, 1);

   
  iRen->Initialize();
  iRen->Start();
  renWin->Render();
   

}


修改后的程序，调试时没有错误，但是执行时无法显示窗口，是哪里出了问题呢？有高手解答下吗？

[解决办法]
把
vtkCamera *camera = vtkCamera::New();
camera->SetPosition(5.0,0.0,0.0);
camera->SetFocalPoint(-1.0,0.0,0.0);
camera->SetViewUp(0.0,1.0,0.0);
ren->SetActiveCamera(camera);
这段代码注释掉就可以了，为什么我也不知道，我也刚刚接触VTK。