[vtkusers] vtkExtractVOI and volume raycast

[Richard Layman]

Hope I get responses this time.  Sorry for no subject. I am also attaching 
the screen shot for the two cases.

>From: "Richard Layman" <mdl_126 at hotmail.com>
>To: vtkusers at vtk.org
>Subject: [vtkusers] (no subject)
>Date: Mon, 19 Dec 2005 14:38:04 -0500
>
>Hi everyone,
>
>I made some changes to the VolumeRendering/SimpleRayCast example. Basically 
>what I wanted to do is to dynamically select a subvolume within a given 
>data volume to render. I use vtkExtractVOI to get the subvolume I want and 
>feed this to the rendering pipeline. An outline is added for reference.
>
>As program starts it displays the whole extent. At the press of a key, the 
>vtkExtractVOI is given a new extent. And I was hoping to see the rendering 
>of the subvolume. This indeed works on Windows. However on my Linux system 
>the raycast rendering was shifted relative to the new outline.
>
>My modified code is shown below. Could anyone tell me if this is the right 
>way to do this or what I need to do to make it work? I am using vtk 4.2 if 
>it's relevant.
>
>Thanks.
>
>
>#!/usr/bin/env python
>
># This is a simple volume rendering example that uses a
># vtkVolumeRayCast mapper
>
>import vtk
>from vtk.util.misc import vtkGetDataRoot
>VTK_DATA_ROOT = vtkGetDataRoot()
>
># Create the standard renderer, render window and interactor
>ren = vtk.vtkRenderer()
>renWin = vtk.vtkRenderWindow()
>renWin.AddRenderer(ren)
>iren = vtk.vtkRenderWindowInteractor()
>iren.SetRenderWindow(renWin)
>
># Create the reader for the data
>reader = vtk.vtkStructuredPointsReader()
>reader.SetFileName(VTK_DATA_ROOT + "/Data/ironProt.vtk")
>
>#*** voi ***
>reader.Update()
>extent = reader.GetOutput().GetWholeExtent()
>print 'extent:', extent
>voi = vtk.vtkExtractVOI()
>voi.SetInput(reader.GetOutput())
>reader = voi
>
># Create transfer mapping scalar value to opacity
>opacityTransferFunction = vtk.vtkPiecewiseFunction()
>opacityTransferFunction.AddPoint(20, 0.0)
>opacityTransferFunction.AddPoint(255, 0.2)
>
># Create transfer mapping scalar value to color
>colorTransferFunction = vtk.vtkColorTransferFunction()
>colorTransferFunction.AddRGBPoint(0.0, 0.0, 0.0, 0.0)
>colorTransferFunction.AddRGBPoint(64.0, 1.0, 0.0, 0.0)
>colorTransferFunction.AddRGBPoint(128.0, 0.0, 0.0, 1.0)
>colorTransferFunction.AddRGBPoint(192.0, 0.0, 1.0, 0.0)
>colorTransferFunction.AddRGBPoint(255.0, 0.0, 0.2, 0.0)
>
># The property describes how the data will look
>volumeProperty = vtk.vtkVolumeProperty()
>volumeProperty.SetColor(colorTransferFunction)
>volumeProperty.SetScalarOpacity(opacityTransferFunction)
>volumeProperty.ShadeOn()
>volumeProperty.SetInterpolationTypeToLinear()
>
># The mapper / ray cast function know how to render the data
>compositeFunction = vtk.vtkVolumeRayCastCompositeFunction()
>volumeMapper = vtk.vtkVolumeRayCastMapper()
>volumeMapper.SetVolumeRayCastFunction(compositeFunction)
>volumeMapper.SetInput(reader.GetOutput())
>
># The volume holds the mapper and the property and
># can be used to position/orient the volume
>volume = vtk.vtkVolume()
>volume.SetMapper(volumeMapper)
>volume.SetProperty(volumeProperty)
>
>#*** outline ***
>outline = vtk.vtkOutlineFilter()
>outline.SetInput(reader.GetOutput())
>olmapper = vtk.vtkPolyDataMapper()
>olmapper.SetInput(outline.GetOutput())
>olactor = vtk.vtkActor()
>olactor.SetMapper(olmapper)
>olactor.GetProperty().SetColor(0,0,0)
>ren.AddActor(olactor)
>
>ren.AddVolume(volume)
>ren.SetBackground(1, 1, 1)
>renWin.SetSize(600, 600)
>renWin.Render()
>
>def CheckAbort(obj, event):
>    if obj.GetEventPending() != 0:
>        obj.SetAbortRender(1)
>
>def keypress(obj, event):
>    print 'key pressed'
>    newext = list(extent)
>    for i in range(0, 6, 2):
>        newext[i] = (newext[i] + newext[i+1]) / 2
>    print 'new extent:', newext
>    voi.SetVOI(*newext)
>    #ren.ResetCamera()
>    #ren.ResetCameraClippingRange()
>    renWin.Render()
>
>renWin.AddObserver("AbortCheckEvent", CheckAbort)
>iren.AddObserver("KeyPressEvent", keypress)
>
>iren.Initialize()
>renWin.Render()
>iren.Start()
>
>_________________________________________________________________
>Don’t just search. Find. Check out the new MSN Search! 
>http://search.msn.click-url.com/go/onm00200636ave/direct/01/
>
>_______________________________________________
>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

_________________________________________________________________
Don’t just search. Find. Check out the new MSN Search! 
http://search.msn.click-url.com/go/onm00200636ave/direct/01/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: linux.png
Type: image/png
Size: 21630 bytes
Desc: not available
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20051220/2124691b/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: windows.png
Type: image/png
Size: 22967 bytes
Desc: not available
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20051220/2124691b/attachment-0001.png>