[vtkusers] GetColor from vtkLookupTable problem

[Jothy]

Yes you are correct! Later for unknow reason I changed it to [1.0,5.0]

Thanks,

Jothy



On Fri, Jul 9, 2010 at 4:12 PM, Eric E. Monson <emonson at cs.duke.edu> wrote:

> I'm glad it's working, but in your original code you had range1=[1.0,6.0]
> and generated three contours from that, so the middle value was 3.5
>
> -Eric
>
> On Jul 9, 2010, at 11:08 AM, Jothy wrote:
>
> Wow!
>
> It works Eric, I thought x is the number of conotur in GetColor(x,color),
> but now realized it's the scalar value.
>
> The values are 1,3,5 (by using ContourFilter->GetValue(0/1/2).
>
> Thanks very much,
>
> Jothy
>
>
> On Fri, Jul 9, 2010 at 3:58 PM, Eric E. Monson <emonson at cs.duke.edu>wrote:
>
>> Well, you're requesting the color for a scalar value of 2.0 and your
>> contours are at 1.0, 3.5 and 6.0 -- if you do GetColor(3.5,cc) you get back
>> [0.0, 1.0, 0.0], which is the color of your middle contour, right?
>>
>> -Eric
>>
>> On Jul 9, 2010, at 10:50 AM, Jothy wrote:
>>
>> But this color which translates to (242,255,0) in another RGB format
>> doesn't match with any of the actual contour colors.
>>
>> See the attached pic.
>>
>> Thanks,
>>
>> Jothy
>>
>> On Fri, Jul 9, 2010 at 3:44 PM, Eric E. Monson <emonson at cs.duke.edu>wrote:
>>
>>> I think I'm just adding two lines to your code and it prints
>>>
>>> [0.94509803921568625, 1.0, 0.0] color
>>>
>>> import vtk
>>>
>>> quadric =vtk.vtkQuadric()
>>> quadric.SetCoefficients(1,2,3,0,1,0,0,0,0,0);
>>>
>>> sample = vtk.vtkSampleFunction();
>>> sample.SetSampleDimensions(40,40,40);
>>> sample.SetImplicitFunction(quadric);
>>>
>>> #Generate implicit surface
>>> contour = vtk.vtkContourFilter();
>>> contour.SetInput(sample.GetOutput());
>>> range1=[1.0,6.0]
>>> contour.GenerateValues(3,range1);
>>>
>>> # The contour lines are mapped to the graphics library.
>>> contMapper = vtk.vtkPolyDataMapper()
>>> contMapper.SetInputConnection(contour.GetOutputPort())
>>> contMapper.SetScalarRange(0,7)
>>>
>>> contActor = vtk.vtkActor()
>>> contActor.SetMapper(contMapper)
>>>
>>> mapr=contMapper.GetLookupTable()
>>>
>>> # TWO NEW LINES
>>> mapr.SetRange(0,7)
>>> mapr.Build()
>>>
>>> cc=[0,0,0]
>>> mapr.GetColor(2,cc)
>>> print cc,'color'
>>>
>>> # Create the renderer, render window, and interactor.
>>> ren = vtk.vtkRenderer()
>>> renWin = vtk.vtkRenderWindow()
>>> renWin.AddRenderer(ren)
>>> iren = vtk.vtkRenderWindowInteractor()
>>> iren.SetRenderWindow(renWin)
>>>
>>> # Set the background color to white. Associate the actors with the
>>> # renderer.
>>> ren.SetBackground(0,0,0)
>>> ren.AddActor(contActor)
>>>
>>> # Zoom in a little bit.
>>> ren.ResetCamera()
>>> ren.GetActiveCamera().Zoom(1)
>>>
>>> # Initialize and start the event loop.
>>> iren.Initialize()
>>> renWin.Render()
>>> iren.Start()
>>>
>>>
>>> On Jul 9, 2010, at 10:40 AM, Jothy wrote:
>>>
>>> Hi Eric,
>>>
>>> Now I get "None" color
>>>
>>> What's wrong?
>>>
>>> Jothy
>>>
>>> On Fri, Jul 9, 2010 at 3:20 PM, Eric E. Monson <emonson at cs.duke.edu>wrote:
>>>
>>>> Hey Jothy,
>>>>
>>>> If you move your GetColor() call after the first Render(), then it will
>>>> get the correct value. The problem is that at the point you're trying to
>>>> grab the color from the lookup table it's not really built yet (you can try
>>>> GetRange() to see that it's still (0,1) when you're calling for the color at
>>>> 2, for example).
>>>>
>>>> So, you can either grab the color after the Render() call, or explicitly
>>>> call SetRange(0,7) and then Build() on the LUT before you try to grab the
>>>> color.
>>>>
>>>> -Eric
>>>>
>>>>  ------------------------------------------------------
>>>> Eric E Monson
>>>> Duke Visualization Technology Group
>>>>
>>>>
>>>> On Jul 9, 2010, at 7:57 AM, Jothy wrote:
>>>>
>>>> Hi all,
>>>>
>>>> I am trying to get the color of cntours using
>>>> Mapper->GetLookupTable()->GetColor(0,color)
>>>>
>>>> But the color doesn't exactly matches with the actual one!
>>>>
>>>> What the problem in this code?
>>>>
>>>>
>>>> *import vtk
>>>>
>>>> quadric =vtk.vtkQuadric()
>>>> quadric.SetCoefficients(1,2,3,0,1,0,0,0,0,0);
>>>>
>>>> sample = vtk.vtkSampleFunction();
>>>> sample.SetSampleDimensions(40,40,40);
>>>> sample.SetImplicitFunction(quadric);
>>>>
>>>> #Generate implicit surface
>>>> contour = vtk.vtkContourFilter();
>>>> contour.SetInput(sample.GetOutput());
>>>> range1=[1.0,6.0]
>>>> contour.GenerateValues(3,range1);
>>>>
>>>>
>>>>
>>>> # The contour lines are mapped to the graphics library.
>>>> contMapper = vtk.vtkPolyDataMapper()
>>>> contMapper.SetInputConnection(contour.GetOutputPort())
>>>> contMapper.SetScalarRange(0,7)
>>>>
>>>> contActor = vtk.vtkActor()
>>>> contActor.SetMapper(contMapper)
>>>>
>>>> mapr=contMapper.GetLookupTable()
>>>> cc=[0,0,0]
>>>> mapr.GetColor(2,cc)
>>>> print cc,'color'
>>>>
>>>>
>>>> # Create the renderer, render window, and interactor.
>>>> ren = vtk.vtkRenderer()
>>>> renWin = vtk.vtkRenderWindow()
>>>> renWin.AddRenderer(ren)
>>>> iren = vtk.vtkRenderWindowInteractor()
>>>> iren.SetRenderWindow(renWin)
>>>>
>>>> # Set the background color to white. Associate the actors with the
>>>> # renderer.
>>>> ren.SetBackground(0,0,0)
>>>> ren.AddActor(contActor)
>>>>
>>>>
>>>> # Zoom in a little bit.
>>>> ren.ResetCamera()
>>>> ren.GetActiveCamera().Zoom(1)
>>>>
>>>> # Initialize and start the event loop.
>>>> iren.Initialize()
>>>> renWin.Render()
>>>> iren.Start()*
>>>>
>>>> Thanks,
>>>> Jothy
>>>>
>>>>
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>>>>
>>>
>>>
>> <untitled.TIF>
>>
>>
>>
>
>
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