[vtkusers] GetColor from vtkLookupTable problem

[Jothy]

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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