[vtkusers] Inverse visualisation of points clouds

[Evgeniy Lalovski]

Hi all,
I'm trying to make a surface from a txt file containing the coordinates of 
the contour exterior of slices of MRI scan(black contour on white 
background).I put the points in PolyData and then use 
SurfaceReconstructionFilter and ContourFilter.But what I get is not that I 
expect.I get a surface of the background of the images not with the contours 
and it has some holes in it althought the slices are ok.How can I invert the 
surface and get it for my contours.

here is a part of my txt file: //coordinates of the black pixels I want to 
visualize
498 263 0   //for the first slice etc.
499 263 0
500 263 0
501 263 0
502 263 0
507 263 0
508 263 0
.............

and here's the code that i use

#include "vtkPolyData.h"
#include "vtkPoints.h"
#include <stdio.h>
#include "vtkSurfaceReconstructionFilter.h"
#include "vtkContourFilter.h"
#include "vtkSmoothPolyDataFilter.h"
#include "vtkReverseSense.h"
#include "vtkProperty.h"
#include "vtkCamera.h"

#include "vtkPolyDataMapper.h"
#include "vtkActor.h"
#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"

int main( int argc, char *argv[] )
{
  FILE *donnees = fopen("points.txt","r");

  vtkPolyData *data = vtkPolyData::New();
  vtkPoints *points = vtkPoints::New();

int iCounter = 0;
while (!feof(donnees))
    {
        fprintf(stdout,"reading points: %i\r", iCounter);
        float x, y, z;
        fscanf(donnees,"%f %f %f\n", &x, &y, &z);
        points->InsertPoint(iCounter++, x, y, z);
    }

data->SetPoints(points);
fclose(donnees);
fprintf(stdout,"\n\n");

// Construire la  surface et cree une isosurface
vtkSurfaceReconstructionFilter *surf = 
vtkSurfaceReconstructionFilter::New();
surf->SetInput(data);
vtkContourFilter *cf = vtkContourFilter::New();
cf->SetInput((vtkDataSet*)surf->GetOutput());
cf->SetValue(0, 0.0);

#ifdef _SMOOTHING_
    vtkSmoothPolyDataFilter *smoother = vtkSmoothPolyDataFilter::New();
    smoother->SetInput(cf->GetOutput());
    smoother->SetNumberOfIterations(50);

    vtkPolyDataNormals *normals = vtkPolyDataNormals::New();
    normals->SetInput(smoother->GetOutput());
    normals->FlipNormalsOn();

    vtkPolyDataMapper *map = vtkPolyDataMapper::New();
    map->SetInput(normals->GetOutput());
#else
    vtkReverseSense *reverse = vtkReverseSense::New();
    reverse->SetInput(cf->GetOutput());
    reverse->ReverseCellsOn();
    reverse->ReverseNormalsOn();

    vtkPolyDataMapper *map = vtkPolyDataMapper::New();
    map->SetInput(reverse->GetOutput());
#endif

    map->ScalarVisibilityOff();

    vtkActor *surfaceActor = vtkActor::New();
    surfaceActor->SetMapper(map);
    surfaceActor->GetProperty()->SetDiffuseColor(1.0000, 0.3882, 0.2784);
    surfaceActor->GetProperty()->SetSpecularColor(1, 1, 1);
    surfaceActor->GetProperty()->SetSpecular(.4);
    surfaceActor->GetProperty()->SetSpecularPower(50);

    vtkCamera *camera = vtkCamera::New();
    camera->SetPosition(1,1,1);
    camera->SetFocalPoint(0,0,0);

    vtkRenderer *renderer = vtkRenderer::New();
    vtkRenderWindow *renWin = vtkRenderWindow::New();
    renWin->AddRenderer(renderer);

    vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
    iren->SetRenderWindow(renWin);

    renderer->AddActor(surfaceActor);
    renderer->SetActiveCamera(camera);
    renderer->GetActiveCamera()->SetFocalPoint(0, 0, 0);
    renderer->GetActiveCamera()->SetPosition(1, 0, 0);
    renderer->GetActiveCamera()->SetViewUp(0, 0, 1);
    renderer->ResetCamera();
    renderer->GetActiveCamera()->Azimuth(20);
    renderer->GetActiveCamera()->Elevation(30);
    renderer->GetActiveCamera()->Dolly(1.2);
    renderer->ResetCameraClippingRange();
    renderer->SetBackground(1,1,1);

    renWin->SetSize(300,300);

    renWin->Render();
    iren->Start();

    points->Delete();
    data->Delete();
    surf->Delete();
    cf->Delete();
#ifdef _SMOOTHING_
    smoother->Delete();
    normals->Delete();
#else
    reverse->Delete();
#endif
    map->Delete();
    surfaceActor->Delete();
    camera->Delete();
    renderer->Delete();
    renWin->Delete();
    iren->Delete();

return 0;
}


Any suggestions are welcome.
Evgeni

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