[vtkusers] vtkFastSplatter broken?

[Cory Quammen]

Hi Richard,

I think you had two problems in your code:

1). The vtkFastSplatter was auto-determining the origin and pixel
spacing of the output image. When you moved the one point around, the
origin was adjusted so that it was always at the location of the one
point. This appeared in the renderer as though nothing was happening.
You can fix this by adding a call to

splatter->SetModelBounds(...)

to some fixed bounding box.

2). Moving points 2-5 by 1 unit in space won't really be visible in an
image where the voxel size is also 1 and the splat is relatively
large. You can fix this by moving the points a further distance.

Here is a modified version of your example where the points show up
where expected:

/*
 * Copyright 2004 Sandia Corporation.
 * Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
 * license for use of this work by or on behalf of the
 * U.S. Government. Redistribution and use in source and binary forms, with
 * or without modification, are permitted provided that this Notice and any
 * statement of authorship are reproduced on all copies.
 */

// Simple test of vtkFastSplatter
#include "vtkImageData.h"
#include "vtkImageShiftScale.h"
#include "vtkFastSplatter.h"
#include "vtkImageViewer2.h"
#include "vtkPoints.h"
#include "vtkPolyData.h"
#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"

#include "vtkSmartPointer.h"
#define VTK_CREATE(type, name) \

  vtkSmartPointer<type> name = vtkSmartPointer<type>::New()

#include <math.h>

const int SPLAT_IMAGE_SIZE = 100;

int main(int, char *[])
{
  // For the purposes of this example we'll build the splat image by
  // hand.

  VTK_CREATE(vtkImageData, SplatImage);
  SplatImage->SetDimensions(SPLAT_IMAGE_SIZE, SPLAT_IMAGE_SIZE, 1);
  SplatImage->AllocateScalars(VTK_FLOAT, 1);

  for (int i = 0; i < SPLAT_IMAGE_SIZE; ++i)
    {
    for (int j = 0; j < SPLAT_IMAGE_SIZE; ++j)
      {
      double xCoord = 1 - fabs(  (i - SPLAT_IMAGE_SIZE/2)
                                 / (SPLAT_IMAGE_SIZE/2.0) );
      double yCoord = 1 - fabs(  (j - SPLAT_IMAGE_SIZE/2)
                                 / (SPLAT_IMAGE_SIZE/2.0) );

      SplatImage->SetScalarComponentFromDouble(i, j, 0, 0,
                                               xCoord * yCoord );
      }
    }

  VTK_CREATE(vtkPolyData, SplatPoints);
  VTK_CREATE(vtkPoints, Points);

  Points->SetNumberOfPoints( 5 );
  double point[3];

  // Move the points further
  point[0] = 100;
  point[1] = 100;
  point[2] = 0;
  Points->SetPoint( 0, point );

  point[0] = 100;
  point[1] = 0;
  point[2] = 0;
  Points->SetPoint( 1, point );

  point[0] = 0;
  point[1] = 100;
  point[2] = 0;
  Points->SetPoint( 2, point );

  point[0] = 0;
  point[1] = 0;
  point[2] = 0;
  Points->SetPoint( 3, point );

  point[0] = 199;
  point[1] = 199;
  point[2] = 0;
  Points->SetPoint( 4, point );

  SplatPoints->SetPoints(Points);

  VTK_CREATE(vtkFastSplatter, splatter);
  splatter->SetInputData( SplatPoints );
  splatter->SetOutputDimensions( 2*SPLAT_IMAGE_SIZE,
                                 2*SPLAT_IMAGE_SIZE,
                                 1 );

  // Fix the model bounds rather than relying on vtkFastSplatter to
calculate them
  splatter->SetModelBounds(0, 199, 0, 199, 0, 0);
  splatter->SetInputData(1, SplatImage );

  // The image viewers and writers are only happy with unsigned char
  // images.  This will convert the floats into that format.
  VTK_CREATE(vtkImageShiftScale, resultScale);
  resultScale->SetOutputScalarTypeToUnsignedChar();
  resultScale->SetShift(0);
  resultScale->SetScale(255);
  resultScale->SetInputConnection( splatter->GetOutputPort() );

  splatter->Update();
  resultScale->Update();

  splatter->GetOutput()->Print(cout);

  // Set up a viewer for the image.  vtkImageViewer and
  // vtkImageViewer2 are convenient wrappers around vtkActor2D,
  // vtkImageMapper, vtkRenderer, and vtkRenderWindow.  All you need
  // to supply is the interactor and hooray, Bob's your uncle.
  VTK_CREATE(vtkImageViewer2, ImageViewer);
  ImageViewer->SetInputConnection( resultScale->GetOutputPort() );
  ImageViewer->SetColorLevel(127);
  ImageViewer->SetColorWindow(255);

  VTK_CREATE(vtkRenderWindowInteractor, iren);
  ImageViewer->SetupInteractor(iren);

  ImageViewer->Render();
  ImageViewer->GetRenderer()->ResetCamera();

  iren->Initialize();
  ImageViewer->Render();
  iren->Start();

  return EXIT_SUCCESS;
}

HTH,
Cory


On Thu, Dec 17, 2015 at 6:58 AM, mbcx9rb9 <richard.j.brown at live.co.uk> wrote:
> Hi all,
>
> I was hoping to use vtkFastSplatter so I took a look at the test. However,
> it doesn't work how I expected (or how it should, I think).
>
> The example places 5 splatters at various coordinates. But I can't control
> the position of those splats. If I comment out all but the first splat and
> then change the coordinates, it doesn't move!
>
> Below is the relevant code, can someone confirm that if they change point[0]
> and point[1], nothing happens? Then, try adding in a second splat (remember
> to change Points->SetNumberOfPoints( 1 ) to 2), changing its coordinates and
> observe that weird things start happening...
>
>
> /*
>  * Copyright 2004 Sandia Corporation.
>  * Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
>  * license for use of this work by or on behalf of the
>  * U.S. Government. Redistribution and use in source and binary forms, with
>  * or without modification, are permitted provided that this Notice and any
>  * statement of authorship are reproduced on all copies.
>  */
>
> // Simple test of vtkFastSplatter
>
> #include "vtkImageData.h"
> #include "vtkImageShiftScale.h"
> #include "vtkFastSplatter.h"
> #include "vtkImageViewer2.h"
> #include "vtkPoints.h"
> #include "vtkPolyData.h"
> #include "vtkRenderer.h"
> #include "vtkRenderWindow.h"
> #include "vtkRenderWindowInteractor.h"
>
> #include "vtkSmartPointer.h"
> #define VTK_CREATE(type, name) \
>   vtkSmartPointer<type> name = vtkSmartPointer<type>::New()
>
> #include <math.h>
>
> const int SPLAT_IMAGE_SIZE = 100;
>
> int main(int, char *[])
> {
>   // For the purposes of this example we'll build the splat image by
>   // hand.
>
>   VTK_CREATE(vtkImageData, SplatImage);
>   SplatImage->SetDimensions(SPLAT_IMAGE_SIZE, SPLAT_IMAGE_SIZE, 1);
>   SplatImage->AllocateScalars(VTK_FLOAT, 1);
>
>   for (int i = 0; i < SPLAT_IMAGE_SIZE; ++i)
>     {
>     for (int j = 0; j < SPLAT_IMAGE_SIZE; ++j)
>       {
>       double xCoord = 1 - fabs(  (i - SPLAT_IMAGE_SIZE/2)
>                                / (SPLAT_IMAGE_SIZE/2.0) );
>       double yCoord = 1 - fabs(  (j - SPLAT_IMAGE_SIZE/2)
>                                / (SPLAT_IMAGE_SIZE/2.0) );
>
>       SplatImage->SetScalarComponentFromDouble(i, j, 0, 0,
>                                                xCoord * yCoord );
>       }
>     }
>
>   VTK_CREATE(vtkPolyData, SplatPoints);
>   VTK_CREATE(vtkPoints, Points);
>
>   Points->SetNumberOfPoints( 1 );
>   double point[3];
>
>   point[0] = 0;
>   point[1] = 0;
>   point[2] = 0;
>   Points->SetPoint( 0, point );
> /*
>   point[0] = 1;
>   point[1] = 0;
>   point[2] = 0;
>   Points->SetPoint( 1, point );
>
>   point[0] = -1;
>   point[1] = 1;
>   point[2] = 0;
>   Points->SetPoint( 2, point );
>
>   point[0] = 1;
>   point[1] = -1;
>   point[2] = 0;
>   Points->SetPoint( 3, point );
>
>   point[0] = -1;
>   point[1] = -1;
>   point[2] = 0;
>   Points->SetPoint( 4, point );
> */
>   SplatPoints->SetPoints(Points);
>
>   VTK_CREATE(vtkFastSplatter, splatter);
>   splatter->SetInputData( SplatPoints );
>   splatter->SetOutputDimensions( 2*SPLAT_IMAGE_SIZE,
>                                  2*SPLAT_IMAGE_SIZE,
>                                  1 );
>   splatter->SetInputData(1, SplatImage );
>
>   // The image viewers and writers are only happy with unsigned char
>   // images.  This will convert the floats into that format.
>   VTK_CREATE(vtkImageShiftScale, resultScale);
>   resultScale->SetOutputScalarTypeToUnsignedChar();
>   resultScale->SetShift(0);
>   resultScale->SetScale(255);
>   resultScale->SetInputConnection( splatter->GetOutputPort() );
>
>   splatter->Update();
>   resultScale->Update();
>
>   // Set up a viewer for the image.  vtkImageViewer and
>   // vtkImageViewer2 are convenient wrappers around vtkActor2D,
>   // vtkImageMapper, vtkRenderer, and vtkRenderWindow.  All you need
>   // to supply is the interactor and hooray, Bob's your uncle.
>   VTK_CREATE(vtkImageViewer2, ImageViewer);
>   ImageViewer->SetInputConnection( resultScale->GetOutputPort() );
>   ImageViewer->SetColorLevel(127);
>   ImageViewer->SetColorWindow(255);
>
>   VTK_CREATE(vtkRenderWindowInteractor, iren);
>   ImageViewer->SetupInteractor(iren);
>
>   ImageViewer->Render();
>   ImageViewer->GetRenderer()->ResetCamera();
>
>   iren->Initialize();
>   ImageViewer->Render();
>   iren->Start();
>
>   return EXIT_SUCCESS;
> }
>
>
>
>
> --
> View this message in context: http://vtk.1045678.n5.nabble.com/vtkFastSplatter-broken-tp5735566.html
> Sent from the VTK - Users mailing list archive at Nabble.com.
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-- 
Cory Quammen
R&D Engineer
Kitware, Inc.