[vtkusers] Fwd: Volume Rendering with multiple-array data

[Randall Hand]

Still looking for any help with this... I've gotten it to work witht
he vtkVolumeTextureMapper2D just fine, but simply replacing that with
the vtkVolumeRayCastMapper calls results in all kinds of weird
behaviour.

Sometimes it exits with a segfault/core dump, but no error.  

Sometimes it runs to completion, but the volume rendering doesn't work
(I get the text & outline, but no data).

Most commonly I get anywhere from 1 to 3 messages like this:
ERROR: In /viz/home/rhand/src/ezViz/Utilities/VTK/Filtering/vtkExecutive.cxx,
line 519
vtkStreamingDemandDrivenPipeline (0x1d6038d0): Non-forwarded requests
are not yet implemented.

And sometimes I get garbage like this: (looks like multiple errors interlaced)
ERROR: In /viz/home/rhand/src/ezViz/Utilities/VTK/FiltEEeRRrRRiOOnRRg::/
 vIItnnk  E//xvveiiczzu//thhioovmmeee.//crrxhhxaa,nn ddl//issnrrecc
//5ee1zz9VV
iivzzt//kUUStttiirlleiiattmiiieenssg//DVVeTTmKKa//nFFdiiDllrttieevrreiinnnPggi//pvvettlkkiEEnxxeee
cc(uu0ttxii1vv0ee9..7cc1xxdxxb,,8  )ll:ii nnNeeo  n55-11f99o
(truncated by me, you get the point)

The messages seem to occur after the ->Render() call, and during the
part where I write it to disk.  (with a vtkTIFFWriter).  Sometimes it
segfaults right after the error messages, and sometimes it just hangs
indefinately.  Once or twice it's even run to completion after the
error messages, but the Volume Rendering never appears.  I'm using
OffScreen rendering with MangledMesa.

Please? Anyone?

---------- Forwarded message ----------
From: Randall Hand <randall.hand at gmail.com>
Date: Wed, 16 Feb 2005 11:29:16 -0600
Subject: Volume Rendering with multiple-array data
To: vtkusers at vtk.org


I have a VTK Dataset with with multiple data values per point.  Each
data point in my rectilinear grid has both a scalar (fractional
occupancy) and a vector (flow velocity).  I want to generate a volume
rendering from this dataset of the scalar field, using the RayCast
volume code.

How do I get from the vtkDataSet that vtkDataSetReader outputs, to the
vtkImageData that the volume rendering routines want?  Currently I'm
using a GaussianSPlatter to convert to an imageData, & a
vtkImageShiftScale to convert from the 0-1float to a 0-255unsigned
char.

Here's an exerpt from my code:

***BEGIN***

    // Load model
    vtkDataSetReader *model = vtkDataSetReader::New();
    model->SetFileName(filename);
    model->Update();
    printf("File loaded\n");
    model->GetOutput()->GetPointData()->GetArray("Fraction")->GetRange(range,0);
    printf("* Range: %f - %f\n", range[0], range[1]);

    vtkMaskPoints *mask = vtkMaskPoints::New();
    mask->SetInput(model->GetOutput());
    mask->RandomModeOn();
    mask->SetMaximumNumberOfPoints(10);
    mask->Update();
    printf("Data Masked\n");
    mask->GetOutput()->GetPointData()->GetArray("Fraction")->GetRange(range,0);
    printf("* Range: %f - %f\n", range[0], range[1]);

    vtkGaussianSplatter *filter = vtkGaussianSplatter::New();
    filter->SetNullValue(0.0);
    filter->SetInput(mask->GetOutput());
    filter->Update();
    printf("Filter ran\n");

    vtkImageShiftScale *scaled = vtkImageShiftScale::New();
    scaled->SetInput(filter->GetOutput());
    scaled->SetScale(255.0);
    scaled->SetOutputScalarTypeToUnsignedChar();
    scaled->Update();
    printf("Data Scaled ran\n");
    printf("* Scaled data arrays:\n");
    vtkPointData *dataptr = scaled->GetOutput()->GetPointData();
    for(n=0; n< dataptr->GetNumberOfArrays(); n++) {
        printf("*   [%i] \"%s\"\n", n, dataptr->GetArrayName(n));
    }
    scaled->GetOutput()->GetPointData()->GetArray(0)->GetRange(range,0);
    printf("* Range: %f - %f\n", range[0], range[1]);
    vtkGaussianSplatter *filter = vtkGaussianSplatter::New();
    filter->SetNullValue(0.0);
    filter->SetInput(mask->GetOutput());
    filter->Update();
    printf("Filter ran\n");

    vtkImageShiftScale *scaled = vtkImageShiftScale::New();
    scaled->SetInput(filter->GetOutput());
    scaled->SetScale(255.0);
    scaled->SetOutputScalarTypeToUnsignedChar();
    scaled->Update();
    printf("Data Scaled ran\n");
    printf("* Scaled data arrays:\n");
    vtkPointData *dataptr = scaled->GetOutput()->GetPointData();
    for(n=0; n< dataptr->GetNumberOfArrays(); n++) {
        printf("*   [%i] \"%s\"\n", n, dataptr->GetArrayName(n));
    }
    scaled->GetOutput()->GetPointData()->GetArray(0)->GetRange(range,0);
    printf("* Range: %f - %f\n", range[0], range[1]);

    vtkVolumeRayCastCompositeFunction *compFunc =
                vtkVolumeRayCastCompositeFunction::New();
    compFunc->SetCompositeMethodToInterpolateFirst();

    vtkPiecewiseFunction *xf_Opacity = vtkPiecewiseFunction::New();
    xf_Opacity->AddPoint(0,0.0);
    xf_Opacity->AddPoint(255,1.0);

    vtkColorTransferFunction *xf_Color = vtkColorTransferFunction::New();
    xf_Color->AddRGBPoint(0, 0, 0, 1);
    xf_Color->AddRGBPoint(255, 0, 0, 1);

    vtkVolumeProperty *volProp = vtkVolumeProperty::New();
    volProp->SetColor(xf_Color);
    volProp->SetScalarOpacity(xf_Opacity);
    volProp->SetInterpolationTypeToLinear();

    modelMapper = vtkVolumeRayCastMapper::New();
    modelMapper->SetInput(scaled->GetOutput());
    modelMapper->SetVolumeRayCastFunction(compFunc);
//  modelMapper->Update();

    printf("Mapper updated\n");
    vtkVolume *volume = vtkVolume::New();
    volume->SetMapper(modelMapper);
    volume->SetProperty(volProp);
***END***

When I run this, tho, I get the following output:
=============== BEGIN OUTPUT ==============
Loading file test.vtk...
File loaded
* Range: 0.000000 - 1.000000
Data Masked
* Range: 0.000000 - 1.000000
Filter ran
Data Scaled ran
* Scaled data arrays:
*   [0] "(null)"
* Range: 0.000000 - 253.000000
Mapper updated
ERROR: In /viz/home/rhand/src/ezViz/Utilities/VTK/Filtering/vtkExecutive.cxx,
line 519
vtkStreamingDemandDrivenPipeline (0x109843b8): Non-forwarded requests
are not yet implemented.

Segmentation fault (core dumped)
================ END OUTPUT ============

Any ideas?
--
Randall Hand
http://www.yeraze.com


-- 
Randall Hand
http://www.yeraze.com