[vtkusers] color mapping

[Deric Stone]

Where are you using the lookup table? Can you use vtkColorTransferFunction or vtkDiscretizableColorTransferFunction instead? There you would be able to specify ranges.

 

Note that GetColor(...) and MapValue(...) are not declared virtual in the vtkLookupTable class so cannot be overridden.

 

Kind regards,

Deric Stone

 

From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf Of Frédéric Speisser
Sent: Monday, December 03, 2012 6:20 PM
To: Johannes Strecha
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] color mapping

 

Thank you Johannes for your answer,

Yes, I know this algorithm, I also use it to filter data.
But here my aim is not to filter data out-of-range but to keep these data visible but set in a custom color.

Kind regards,
Frédéric

Le 03/12/2012 18:12, Johannes Strecha a écrit :

	Hello,
	
	I can't give you a direct answer, but I think what you want can be done with the vtkClipDataSet filter (5.8). See the reference for details. I assume that adjusting the lookup table would work faster, though.
	
	When trying to realize a "filled contour plot" by adjusting the lookup table (to a series of steps) I experienced that some interpolation was performed nonetheless and I ended up with blurred filled contours. Maybe this would also happen in your case.
	
	Kind regards,
	Johannes Strecha.

	 

	On Mon, Dec 3, 2012 at 5:31 PM, Frédéric Speisser <speisser at kappaeng.com> wrote:

	Hi all,
	
	
	I'm using vtkLookupTable::SetTableRange to remap colors of a LUT to a custom range of a given scalar values. 
	
	This works great but per default and as explained in API documentation :
	Scalar values less than minimum range value are clamped to minimum range value. Scalar values greater than maximum range value are clamped to maximum range value.
	So values out of range are displayed in minimum range value color (for those under custom range) and in maximum range value color (for those over custom range).
	I would like to display out-of-range values in a custom color, so that for example all values under and over custom range are displayed in black.
	I began to write a class MyVtkLookupTable which inherits from vtkLookupTable and i tried to override GetColor(double v, double rgb[3]) and MapValue(double v) to be able to override color displayed but it seems not to work.
	Is it possible to do that by overriding vtk classes ? If yes, which method/classes should I override ?
	
	Any clues are wellcome, thank you,
	
	
	
	Frédéric 

	
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