[vtkusers] artifacts while rendering 3d surface

[Tim Hutton]

Hi Ajit,

vtkSurfaceReconstructionFilter doesn't work terribly well I'm afraid. It 
needs the surface to be densely-sampled and quite noise-free. It also 
requires that the surface be closed (and probably some other things as 
well). There are some well-documented cases showing similar results to 
yours at:

http://archive.ncsa.uiuc.edu/People/heiland/vtk/scatter/sphere/

You can try vtkPowerCrustSurfaceReconstruction, it works much better:

http://www.eastman.ucl.ac.uk/~thutton/powercrust/

Tim.

At 23:33 25/06/2003 +0530, Ajit Rajwadé wrote:
>Sorry....forgot to attach the file
>
>
>Hello,
>
>I am using the following piece of code to render a 3D surface given the 
>X,Y,Z coordinates of several equi-sampled points of the surface . While 
>rendering the surface, I get very weird artifacts. For instance, here is 
>an attached file that contains a rendered sphere.  I am unable to trace 
>the bug, what could the cause be?
>
>The code is here:
>
>               // Read all the vertices into an ARRAY called "mean"
>
>                 vtkRenderer *ren = vtkRenderer::New();
>                 vtkRenderWindow *renWin = vtkRenderWindow::New();
>                 renWin->AddRenderer(ren);
>                 renWin->SetSize (300,300);
>
>                 vtkRenderWindowInteractor *iren = 
> vtkRenderWindowInteractor::New();
>                 iren->SetRenderWindow(renWin);
>
>               //Inserting points one by one
>                 vtkPoints *meanPoints = vtkPoints::New();
>                 for (i=0;i<SIZE;i++)
>                 {
>                         point[0] = Mean[i][0];
>                         point[1] = Mean[i][1];
>                         point[2] = Mean[i][2];
>                         meanPoints->InsertNextPoint(point);
>                 }
>
>                 // Create a data set. Load the starting points
>                 vtkPolyData *inputDataSet = vtkPolyData::New();
>                 inputDataSet->SetPoints(meanPoints);
>
>                 // Construct the surface
>                 vtkSurfaceReconstructionFilter *surf = 
> vtkSurfaceReconstructionFilter::New();
>                 surf->SetInput(inputDataSet);
>                 printf ("\nSurface construction done...");
>
>                 // Create isosurface (contour value of 0)
>                 vtkContourFilter *cf = vtkContourFilter::New();
>                 cf->SetInput(surf->GetOutput());
>                 cf->SetValue(0,0.0);
>
>                 // PolyNormals Filter to obtain normals for "Smooth Shading"
>                 vtkPolyDataNormals *bNormals = vtkPolyDataNormals::New();
>                 bNormals->SetInput(cf ->GetOutput());
>                 //bNormals->SetFeatureAngle(180.0);
>
>                 // Creates Triangle strips from the Iso-surface
>                 vtkStripper *bStripper = vtkStripper::New();
>                 bStripper->SetInput(bNormals->GetOutput());
>
>                 // Create the mapper and actor and finish up the 
> visualization pipeline
>                 vtkPolyDataMapper *map = vtkPolyDataMapper::New();
>                 map->SetInput(bStripper->GetOutput());
>                 map->ScalarVisibilityOff();
>                 //map->ImmediateModeRenderingOn ();
>
>                 cout << "Mapper construction done..." << endl;
>
>                 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(0.4);
>                 surfaceActor->GetProperty()->SetSpecularPower(50);
>
>                 ren->AddActor(surfaceActor);
>                 ren->SetBackground(1,1,1);
>                 cout << "Surface actor construction done..." << endl;
>
>                 // Interact with data
>                 renWin->Render();
>                 iren->Initialize ();
>                 iren->Start ();
>
>                 printf ("\nPress any key");
>                 scanf ("%d", &choice);
>
>                 // Clean up
>                 ren->RemoveActor (surfaceActor);
>                 meanPoints->Delete();
>                 inputDataSet->Delete();
>                 surf->Delete();
>                 cf->Delete();
>                 map->Delete();
>                 surfaceActor->Delete();
>                 ren->Delete();
>                 renWin->Delete();
>                 //iren->Delete ();
>
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