[vtkusers] Re: Re: Re: Creating a Volume from 2D BMP files.
Sharwari Mavalankar
sharwari at gmail.com
Thu Sep 14 08:47:14 EDT 2006
hi Asish,
How have you named your images?
so your images are stored as IM1.dcm,IM2.dcm,IM3.dcm etc?
Sharwari
On 9/14/06, Yixun Liu <yxliu at fudan.edu.cn> wrote:
>
> Hi,
> vtkVolumeRayCastMapper does not support short type, so rescale it to
> unsigned short using vtkImageShiftScale or use
> vtkFixedPointVolumeRayCastMapper instead of vtkVolumeRayCastMapper.
>
> Hope it help.
>
> Yixun
>
>
> ----- Original Message -----
> *From:* Ashish Singh <mrasingh at gmail.com>
> *To:* Yixun Liu <yxliu at fudan.edu.cn> ; vtkusers at vtk.org
> *Sent:* Thursday, September 14, 2006 1:02 PM
> *Subject:* Re: [vtkusers] Re: Re: Re: Creating a Volume from 2D BMP files.
>
>
> Hi Yixun,
>
> I am using the volumerendering library as you mentioned. But still I am
> getting the following errors.
> 1)ERROR: In ..\..\IO\vtkDICOMImageReader .cxx, line 255
> vtkDICOMImageReader (0033C900): Either a filename was not specified or the
> specified directory does not contain any DICOM images.
>
> 2)ERROR: In ..\..\VolumeRendering\vtkVolumeRayCastMapper.cxx, line 326
> vtkVolumeRayCastMapper (02953718): Cannot volume render data of type
> short, only unsigned char or unsigned short.
>
> The 2nd error keeps repeating itself again and again.
>
> How can I rectify these errors?
>
> My code is as follows:
>
>
> -----
> #include "vtkConeSource.h"
> #include "vtkPolyDataMapper.h "
> #include "vtkRenderWindow.h"
> #include "vtkCamera.h"
> #include "vtkActor.h" #include "vtkImageActor.h"
> #include "vtkOutlineFilter.h"
> #include " vtkProperty.h"
> #include "vtkPolyDataNormals.h"
> #include "vtkContourFilter.h"
> #include "vtkDataSetMapper.h"
> #include "vtkImageMapper.h"
> #include "vtkPiecewiseFunction.h "
> #include "vtkVolumeProperty.h"
> #include "vtkRenderer.h"
> #include "conio.h"
> #include "vtkDICOMImageReader.h"
> #include "vtkImageViewer2.h"
> #include " vtkJPEGReader.h"
> #include "vtkRenderWindowInteractor.h"
> #include "vtkVolumeMapper.h"
> #include "vtkActor2D.h"
> #include "vtkPolyDataMapper.h"
> #include "vtkVolumeRayCastCompositeFuncti on.h "
> #include "vtkVolumeRayCastMapper.h"
>
> void main()
> {
>
> vtkRenderer *arenderer = vtkRenderer::New();
> vtkRenderWindow *renwin = vtkRenderWindow::New();
> vtkDICOMImageReader *img1=vtkDICOMImageReader::New();
>
> img1->SetFilePrefix("D:\\testimages\\dicomset\\IM");
> img1->SetFilePattern("%s%d.dcm");
> img1->SetFileNameSliceOffset(1);
> img1->SetFileNameSliceSpacing(1);
> img1->SetDataExtent(0,511,0,511,1,10);//512x512 images and 10 slices
> img1->SetDataSpacing(360.0/512,360.0/512,1.0); //my image is 36cm x 36cm
> and 512x512
> img1->SetDataOrigin(0.0,0.0,0.0);
> img1->Update();
>
> vtkVolume *vol=vtkVolume::New();
> vtkVolumeRayCastMapper *volumemapper = vtkVolumeRayCastMapper::New();
> vtkVolumeRayCastCompositeFunction
> *rcf=vtkVolumeRayCastCompositeFunction::New();
> volumemapper->SetVolumeRayCastFunction(rcf);
> volumemapper->SetInput(img1->GetOutput());
> vol->SetMapper(volumemapper);
>
> vtkCamera *cam=vtkCamera::New();
> cam->SetViewUp(0,0,-1);
> cam->SetPosition(0,1,0);
> cam->SetFocalPoint(0,0,0);
> cam->ComputeViewPlaneNormal();
>
> arenderer->AddActor(vol);
> arenderer->SetActiveCamera(cam);
> arenderer->ResetCamera();
> arenderer->SetBackground(1,1,1);
>
> renwin->AddRenderer(arenderer);
> vtkRenderWindowInteractor *iren=vtkRenderWindowInteractor::New();
> iren->SetRenderWindow(renwin);
> renwin->Render();
> iren->Initialize();
> iren->Start();
>
> img1->Delete();
> iren->Delete();
> }
> --------
>
> I would appreciate all help.
>
> Thanks,
> Ashish
>
>
>
> On 9/13/06, Yixun Liu <yxliu at fudan.edu.cn> wrote:
> >
> > Hi,
> > When you update vtk from 4.2 to 5.0 the old rendering.lib has been
> > replaced with volumerendering.lib, so be sure that you use the
> > volumerendering.lib instead of rendering.lib in you project
> > configuration.
> >
> > Cheers,
> >
> > Yixun
> >
> > ----- Original Message -----
> > *From:* Ashish Singh <mrasingh at gmail.com>
> > *To:* vtkusers at vtk.org
> > *Cc:* Yixun Liu <yxliu at fudan.edu.cn> ; Amy Squillacote<amy.squillacote at kitware.com>
> > *Sent:* Thursday, September 14, 2006 1:23 AM
> > *Subject:* Re: [vtkusers] Re: Re: Re: Creating a Volume from 2D BMP
> > files.
> >
> >
> > Hi Amy,
> >
> > I don't remember if VTK_USE_RENDERING variable was ON or not. Is there a
> > way to confirm that? However I am able to compile and run other programs
> > from the examples/tutorials directory such as cones etc. as well as read and
> > display single dicom image and interact with it using
> > renderwindowinteractor.
> >
> > Here is my cmakelists.txt file for cone example:
> > ---
> > PROJECT (Step1)
> >
> > FIND_PACKAGE(VTK REQUIRED)
> > IF(NOT VTK_USE_RENDERING)
> > MESSAGE(FATAL_ERROR "Example ${PROJECT_NAME} requires
> > VTK_USE_RENDERING.")
> > ENDIF(NOT VTK_USE_RENDERING)
> > INCLUDE(${VTK_USE_FILE})
> >
> > ADD_EXECUTABLE(Cone Cone.cxx)
> > TARGET_LINK_LIBRARIES(Cone vtkRendering)
> > ----
> > This works fine.
> >
> > The cmakelists.txt file that I use for dicom volume problem is :
> > ----
> > PROJECT (multiimagereader)
> >
> > INCLUDE (${CMAKE_ROOT}/Modules/FindVTK.cmake)
> > IF (USE_VTK_FILE)
> > INCLUDE(${USE_VTK_FILE})
> > ENDIF (USE_VTK_FILE)
> >
> > ADD_EXECUTABLE(multiimagereader multiimagereader.cxx )
> > TARGET_LINK_LIBRARIES(multiimagereader vtkRendering)
> > ----
> > Is there anything that I need to modify in this file?
> >
> > Thanks,
> > Ashish
> >
> >
> > On 9/13/06, Amy Squillacote <amy.squillacote at kitware.com> wrote:
> > >
> > > Hi Ashish,
> > >
> > > When you built VTK, was the VTK_USE_RENDERING CMake variable set to
> > > ON? If it was, are you linking against the vtkVolumeRendering library?
> > >
> > > - Amy
> > >
> > > Ashish Singh wrote:
> > >
> > > Hi Yixun and Sharwari,
> > >
> > > I am trying to solve exactly similar problem but using DICOM images
> > > rather than bmp. But I am getting errors and I can't figure out why. My code
> > > is based on your previous conversation so far. The error that I get is:
> > > (1)error LNK2019: unresolved external symbol "public: static class
> > > vtkVolumeRayCastCompositeFunction * __cdecl
> > > vtkVolumeRayCastCompositeFunction::New(void)"
> > > (?New at vtkVolumeRayCastCompositeFunction@@SAPAV1 at XZ ) referenced in
> > > function _main
> > > (2)error LNK2019: unresolved external symbol "public: static class
> > > vtkVolumeRayCastMapper * __cdecl vtkVolumeRayCastMapper::New(void)"
> > > (?New at vtkVolumeRayCastMapper@@SAPAV1 at XZ) referenced in function _main
> > > (3)fatal error LNK1120: 2 unresolved externals
> > >
> > > Can you please help me figure out what's going wrong here?
> > >
> > > My code is as follows:
> > > -----
> > > #include "vtkConeSource.h"
> > > #include "vtkPolyDataMapper.h "
> > > #include "vtkRenderWindow.h"
> > > #include "vtkCamera.h"
> > > #include "vtkActor.h"
> > > #include "vtkImageActor.h"
> > > #include "vtkOutlineFilter.h"
> > > #include " vtkProperty.h"
> > > #include "vtkPolyDataNormals.h"
> > > #include "vtkContourFilter.h"
> > > #include "vtkDataSetMapper.h"
> > > #include "vtkImageMapper.h"
> > > #include "vtkPiecewiseFunction.h "
> > > #include "vtkVolumeProperty.h"
> > > #include "vtkRenderer.h"
> > > #include "conio.h"
> > > #include "vtkDICOMImageReader.h"
> > > #include "vtkImageViewer2.h"
> > > #include " vtkJPEGReader.h"
> > > #include "vtkRenderWindowInteractor.h"
> > > #include "vtkVolumeMapper.h"
> > > #include "vtkActor2D.h"
> > > #include "vtkPolyDataMapper.h"
> > > #include "vtkVolumeRayCastCompositeFunction.h "
> > > #include "vtkVolumeRayCastMapper.h"
> > >
> > > void main()
> > > {
> > >
> > > vtkRenderer *arenderer = vtkRenderer::New();
> > > vtkRenderWindow *renwin = vtkRenderWindow::New();
> > > vtkDICOMImageReader *img1=vtkDICOMImageReader::New();
> > >
> > > img1->SetFilePrefix("D:\\testimages\\dicomset\\IM");
> > > img1->SetFilePattern("%s%d.dcm");
> > > img1->SetFileNameSliceOffset(1);
> > > img1->SetFileNameSliceSpacing(1);
> > > img1->SetDataExtent(0,511,0,511,1,10);//512x512 images and 10 slices
> > >
> > > img1->SetDataSpacing(360.0/512,360.0/512,1.0); //my image is 36cm x
> > > 36cm and 512x512
> > > img1->SetDataOrigin(0.0,0.0,0.0);
> > > img1->Update();
> > >
> > > vtkVolume *vol=vtkVolume::New();
> > > vtkVolumeRayCastMapper *volumemapper =
> > > vtkVolumeRayCastMapper::New();
> > > vtkVolumeRayCastCompositeFunction
> > > *rcf=vtkVolumeRayCastCompositeFunction::New();
> > > volumemapper->SetVolumeRayCastFunction(rcf);
> > > volumemapper->SetInput(img1->GetOutput());
> > > vol->SetMapper(volumemapper);
> > >
> > > vtkCamera *cam=vtkCamera::New();
> > > cam->SetViewUp(0,0,-1);
> > > cam->SetPosition(0,1,0);
> > > cam->SetFocalPoint(0,0,0);
> > > cam->ComputeViewPlaneNormal();
> > >
> > > arenderer->AddActor(vol);
> > > arenderer->SetActiveCamera(cam);
> > > arenderer->ResetCamera();
> > > arenderer->SetBackground(1,1,1);
> > >
> > > renwin->AddRenderer(arenderer);
> > > vtkRenderWindowInteractor *iren=vtkRenderWindowInteractor::New();
> > > iren->SetRenderWindow(renwin);
> > > renwin->Render();
> > > iren->Initialize();
> > > iren->Start();
> > >
> > > img1->Delete();
> > > iren->Delete();
> > > }
> > > --------
> > > I would really appreciate if anyone can help me.
> > >
> > > Regards,
> > > Ashish
> > >
> > > On 9/7/06, Sharwari Mavalankar < sharwari at gmail.com> wrote:
> > > >
> > > > hi Yixun,
> > > > I'll try and look into why the volume appears darker.
> > > >
> > > > However I'll there are many lines that are appearing on the volume
> > > > (they look like striations).
> > > > Do you know what the reason for that could be?
> > > >
> > > >
> > > > Also if I have to visualize color bmp slices (24 bit ) I need vtkFixedPointVolumeRayCastMapper
> > > > right?
> > > > Thanks
> > > > Sharwari
> > > >
> > > >
> > > > On 9/6/06, Yixun Liu <yxliu at fudan.edu.cn > wrote:
> > > > >
> > > > > Hi,
> > > > > You are right and alwayse taking mm as the unit.
> > > > > SpacingX = 5.12*10/256;
> > > > > SpacingY = 5.12*10/256;
> > > > >
> > > > > Many reason can make the volume look darker.
> > > > > You can change the opacity and color interpolation function to
> > > > > adjust the appearance of the volume. If you use shade you can also change
> > > > > ambient or diffusion coefficient to make the volume look more lighter.
> > > > > Another method is to change the vtkLight in the renderer. vtkLightis a virtual light for 3D rendering. It provides methods to locate and point
> > > > > the light, turn it on and off, and set its brightness and color.
> > > > >
> > > > > Cheers,
> > > > >
> > > > > Yixun Liu
> > > > > ----- Original Message -----
> > > > > *From:* Sharwari Mavalankar <sharwari at gmail.com>
> > > > > *To:* Yixun Liu <yxliu at fudan.edu.cn>
> > > > > *Cc:* VTK <vtkusers at vtk.org>
> > > > > *Sent:* Thursday, September 07, 2006 1:43 AM
> > > > > *Subject:* Re: Re: Re: Creating a Volume from 2D BMP files.
> > > > >
> > > > >
> > > > > hi Yixun,
> > > > > Thank you very much for your email.
> > > > > What exactly do you mean by the physical size of the image?
> > > > > Does it mean the size of the image in cm or mm?
> > > > >
> > > > > For example if my original images are 5.12 cm * 5.12 cm and are
> > > > > 256 * 256 images.
> > > > > What will the data spacing be?
> > > > >
> > > > >
> > > > > Also can you tell me the reason why the 3D volume seems darker
> > > > > than the original images?
> > > > > Is there any way I can scale the intensity of the images?
> > > > > Thanks again,
> > > > > Sharwari
> > > > >
> > > > >
> > > > > On 9/3/06, Yixun Liu <yxliu at fudan.edu.cn > wrote:
> > > > > >
> > > > > > Hi,
> > > > > > If you read color bmp files you should update vtk to 5.0 version
> > > > > > and use vtkFixedPointVolumeRayCastMapper(see last mail). Otherwise, you
> > > > > > should not call
> > > > > > br->SetNumberOfScalarComponents(3);
> > > > > >
> > > > > > 1. You can decide the physical spacing accroding to the image
> > > > > > extent(pixel unit) and its physical size(mm): spacing = size/(extent-1); If
> > > > > > no physical size you have to give a estimation for the spacing.
> > > > > >
> > > > > > 2.The point1 and point2 will define a linear opacity function,
> > > > > > which can be interpolated from the two points. For example, define two
> > > > > > points (intensity1, opacity1)and (intensity2, opacity2) you can get the
> > > > > > opacity3 at intensity3 by opacity3 =
> > > > > > (intensity3-intensity1)/(intensity2-intensity1)*(opacity2-opacity1) +
> > > > > > opacity1
> > > > > >
> > > > > > Hope it help.
> > > > > >
> > > > > > Cheers,
> > > > > >
> > > > > > Yixun Liu
> > > > > >
> > > > > > ----- Original Message -----
> > > > > > *From:* Sharwari Mavalankar <sharwari at gmail.com>
> > > > > > *To:* Yixun Liu <yxliu at fudan.edu.cn>
> > > > > > *Cc:* VTK <vtkusers at vtk.org>
> > > > > > *Sent:* Monday, September 04, 2006 6:50 AM
> > > > > > *Subject:* Re: Re: Creating a Volume from 2D BMP files.
> > > > > >
> > > > > >
> > > > > > hi Yixun,
> > > > > > I implemented the suggestions that you had made.
> > > > > > Now I am getting a 3D volume but it doesnt look anything like
> > > > > > the original 2D slices.
> > > > > > It is much darker in appearance and it's got lines all over it (
> > > > > > it looks as though it's some kind of aliasing).
> > > > > >
> > > > > > I have the following questions to ask you
> > > > > > 1.While using the function SetDataSpacing(x,y,z) how do I decide
> > > > > > the values of the parameters x,y and z.
> > > > > >
> > > > > > 2.While using the Addpoint() function of class
> > > > > > vtkPiecewiseFunction what do the two parameters in the Addpoint function
> > > > > > mean?
> > > > > > How do they affect the output?
> > > > > >
> > > > > >
> > > > > > This is code I have used. Do let me know if you can make any
> > > > > > more sugestions.
> > > > > >
> > > > > >
> > > > > >
> > > > > > //This program reads a single BMP file and plots it as an image.
> > > > > > //The same program will be extended to read multiple images and
> > > > > > create a 3D volume out of 2D slices.
> > > > > >
> > > > > >
> > > > > > #include "vtkRenderer.h"
> > > > > > #include "vtkRenderWindow.h"
> > > > > > #include "vtkRenderWindowInteractor.h"
> > > > > > #include "vtkBMPReader.h"
> > > > > > #include "vtkPolyDataMapper.h"
> > > > > > #include "vtkActor.h"
> > > > > > #include "vtkActor2D.h"
> > > > > > #include "vtkImageActor.h"
> > > > > > #include "vtkOutlineFilter.h"
> > > > > > #include "vtkCamera.h"
> > > > > > #include "vtkProperty.h"
> > > > > > #include "vtkPolyDataNormals.h"
> > > > > > #include "vtkContourFilter.h"
> > > > > > #include "vtkDataSetMapper.h"
> > > > > > #include "vtkImageMapper.h"
> > > > > > #include "vtkVolumeMapper.h"
> > > > > > #include " vtkVolumeRayCastMapper.h"
> > > > > > #include "vtkVolumeRayCastCompositeFunction.h"
> > > > > > #include "vtkPiecewiseFunction.h"
> > > > > > #include "vtkVolumeProperty.h"
> > > > > >
> > > > > >
> > > > > > void main (void)
> > > > > > {
> > > > > >
> > > > > > vtkRenderer *aRenderer = vtkRenderer::New();
> > > > > > vtkRenderWindow *renWin = vtkRenderWindow::New();
> > > > > >
> > > > > > renWin->AddRenderer(aRenderer);
> > > > > > vtkRenderWindowInteractor *iren =
> > > > > > vtkRenderWindowInteractor::New();
> > > > > > iren->SetRenderWindow(renWin);
> > > > > >
> > > > > >
> > > > > > //create an instance of the class vtkBMPReader
> > > > > > vtkBMPReader *br = vtkBMPReader::New();
> > > > > >
> > > > > > br->SetFilePrefix("C:\\Images\\conductivities\\slice");
> > > > > > br->SetFilePattern("%s%d.bmp");
> > > > > > br->SetFileNameSliceOffset(1);
> > > > > > br->SetFileNameSliceSpacing(1);
> > > > > > br->SetNumberOfScalarComponents(3);
> > > > > > br->SetDataSpacing(0.4,0.4,10);
> > > > > > br->SetDataOrigin(0,0,0);
> > > > > > br->SetDataExtent(0,255,0,255,0,7);
> > > > > > br->Update();
> > > > > >
> > > > > > vtkPiecewiseFunction *opacityTransferFunction =
> > > > > > vtkPiecewiseFunction::New();
> > > > > > opacityTransferFunction->AddPoint(20,0.2);
> > > > > > opacityTransferFunction->AddPoint(255,1.0);
> > > > > >
> > > > > > vtkVolumeProperty *volumeProperty = vtkVolumeProperty::New();
> > > > > > volumeProperty->SetScalarOpacity(opacityTransferFunction);
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > vtkVolumeRayCastMapper *VolumeMapper =
> > > > > > vtkVolumeRayCastMapper::New();
> > > > > > vtkVolumeRayCastCompositeFunction *RayCastFunction =
> > > > > > vtkVolumeRayCastCompositeFunction::New();
> > > > > > VolumeMapper->SetVolumeRayCastFunction(RayCastFunction);
> > > > > > VolumeMapper->SetInput(br->GetOutput());
> > > > > >
> > > > > >
> > > > > > vtkVolume *volume = vtkVolume::New();
> > > > > >
> > > > > > VolumeMapper->SetInput(br->GetOutput());
> > > > > > volume->SetMapper(VolumeMapper);
> > > > > >
> > > > > > vtkCamera *aCamera = vtkCamera::New();
> > > > > > aCamera->SetViewUp (0, 0,-1);
> > > > > > aCamera->SetPosition (0, 1, 0);
> > > > > > aCamera->SetFocalPoint (0, 0, 0);
> > > > > > aCamera->ComputeViewPlaneNormal();
> > > > > >
> > > > > >
> > > > > > aRenderer->AddActor(volume);
> > > > > > aRenderer->SetActiveCamera(aCamera);
> > > > > > aRenderer->ResetCamera ();
> > > > > > aRenderer->SetBackground(1,1,1);
> > > > > > renWin->Render();
> > > > > >
> > > > > > iren->Initialize();
> > > > > > iren->Start();
> > > > > >
> > > > > > }
> > > > > >
> > > > > > Thanks again for all your help.
> > > > > > Sharwari
> > > > > >
> > > > > >
> > > > > > On 8/31/06, Yixun Liu <yxliu at fudan.edu.cn > wrote:
> > > > > > >
> > > > > > > Hi,
> > > > > > > Assuming image is 256x256x100. The first file name is image1
> > > > > > > and the last file name is image100. So, SetDataExtent(0, 255, 0, 255, 1,
> > > > > > > 100); The access violation may be caused by wrong extent setting.
> > > > > > >
> > > > > > > If you use vtkVolume, use vtkVolumeRayCastMapper(vtk4.2.2)
> > > > > > > or use vtkFixedPointVolumeRayCastMapper(vtk5.0). Note that if
> > > > > > > you use vtkFixedPointVolumeRayCastMapper you no need to call
> > > > > > > SetVolumeRayCastFunction();
> > > > > > >
> > > > > > > Hope it help.
> > > > > > >
> > > > > > > Yixun Liu
> > > > > > >
> > > > > > > ----- Original Message -----
> > > > > > > *From:* Sharwari Mavalankar <sharwari at gmail.com>
> > > > > > > *To:* Yixun Liu <yxliu at fudan.edu.cn>
> > > > > > > *Cc:* VTK <vtkusers at vtk.org>
> > > > > > > *Sent:* Thursday, August 31, 2006 6:37 PM
> > > > > > > *Subject:* Re: Creating a Volume from 2D BMP files.
> > > > > > >
> > > > > > >
> > > > > > > hi Yixun,
> > > > > > > Thanks for your email.I had a couple of more questions though.
> > > > > > > 1.I do not want to visualize colour slices.They are grey level
> > > > > > > images.
> > > > > > >
> > > > > > > 2.Also if I put SetDataExtent() before the Update() then I am
> > > > > > > getting an access violation error.What does the Update
> > > > > > > function do exactly?
> > > > > > > Also can you tell me what the five parameters in
> > > > > > > SetDataExtent() mean?
> > > > > > >
> > > > > > > 3.If I use vtkVolume what mapper should I use to visualize the
> > > > > > > slices?
> > > > > > >
> > > > > > >
> > > > > > > Thanks again for all your help.
> > > > > > > Sharwari
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > On 8/23/06, Yixun Liu <yxliu at fudan.edu.cn > wrote:
> > > > > > > >
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > If you want to visualize color slices, you need to
> > > > > > > > 1. read these slices. You need to put the SetDataExtent(0,
> > > > > > > > 111, 0, 127, 1, 300);
> > > > > > > > before Update();
> > > > > > > >
> > > > > > > > vtkTIFFReader *v16 = vtkTIFFReader::New();
> > > > > > > >
> > > > > > > > v16->SetFilePrefix("D:\\MyVC\\VTKtest\\Raycasting\\Data\\BrainColor\\brain");
> > > > > > > > v16->SetFilePattern("%s%d.TIF");
> > > > > > > > v16->SetDataExtent(0, 111, 0, 127, 1, 300);
> > > > > > > > v16->SetDataSpacing(1.2,1.2,0.5);
> > > > > > > > v16->SetDataOrigin(0.0, 0.0, 0.0);
> > > > > > > > v16->SetNumberOfScalarComponents(3);
> > > > > > > > v16->Update();
> > > > > > > >
> > > > > > > > 2. Add the 4th component. The first three components are
> > > > > > > > color and the 4th is used to map to opacity. I compute the luminancy
> > > > > > > > according to the firft three components and take it as the 4th component.
> > > > > > > >
> > > > > > > > 3. Opacity map using vtkPiecewiseFunction
> > > > > > > >
> > > > > > > > 4. no need color map function
> > > > > > > >
> > > > > > > > 5. you need vtk5.0
> > > > > > > >
> > > > > > > > Regads,
> > > > > > > >
> > > > > > > > Yixun Liu
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > > > _______________________________________________
> > > > This is the private VTK discussion list.
> > > > Please keep messages on-topic. Check the FAQ at:
> > > > http://www.vtk.org/Wiki/VTK_FAQ
> > > > Follow this link to subscribe/unsubscribe:
> > > > http://www.vtk.org/mailman/listinfo/vtkusers
> > > >
> > > >
> > > >
> > > ------------------------------
> > >
> > > _______________________________________________ This is the private
> > > VTK discussion list. Please keep messages on-topic. Check the FAQ at:
> > > http://www.vtk.org/Wiki/VTK_FAQ Follow this link to
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> > >
> >
> >
>
> _______________________________________________
> This is the private VTK discussion list.
> Please keep messages on-topic. Check the FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
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