[vtkusers] InfoVis: Setting vertex color LUT range?

[Jeff Baumes]

The bounds are currently always set to the range of the data array
being colored, which is done every render (see
vtkGraphLayoutView::PrepareForRendering()). The vertex (and edge)
coloring should have a mode where you specify the fixed bounds you
want.

Another day, another obvious infovis feature that needs to be added ... :)

Jeff

On Wed, Jan 14, 2009 at 4:16 PM, Eric E. Monson <emonson at cs.duke.edu> wrote:
> Hey Jeff,
>
> Thanks for all the help recently. I'll get around to filing some things on
> Mantis soon...
>
> In the meantime I finally figured out how to get at the vertex lookup table
> in the graph mapper inside the view, and then copy values from a color
> transfer function into the LUT to generate my desired diverging color map.
> I'm still having a problem, though, forcing the scalar range of the color
> mapping. (I want it to be symmetric positive and negative, so the middle of
> my color map sits at zero).
>
> Do you know of any way to force a scalar range on the vertex color map (or
> the VertexMapper within the GraphMapper, whichever is really the right way
> to do it) when using a GraphLayoutView?
>
> Thanks,
> -Eric
>
>
> On Jan 12, 2009, at 9:47 AM, Jeff Baumes wrote:
>
>> Looks like a feature request for vtkViewTheme. We should have made it
>> store a general color map, rather than restricting it to HSV ranges.
>> It should be a fairly simple fix. The theme would need to store a
>> lookup table, and the ApplyViewTheme() function in each view would
>> need to use this directly. The old range methods on vtkViewTheme would
>> modify its lookup table.
>>
>> Jeff
>>
>> On Fri, Jan 9, 2009 at 9:47 PM, Eric E. Monson <emonson at cs.duke.edu>
>> wrote:
>>>
>>> Hey folks,
>>>
>>> To color vertices according to an array that contains both positive and
>>> negative values, I need to build a diverging color map (lookup table) and
>>> force the scalar range that's mapped over these colors to be centered on
>>> zero:
>>>
>>> 1.  If I'm using a vtkGraphLayoutView, is there any way to force the
>>> lookup
>>> table to cover a certain range of values (rather than the real range of
>>> the
>>> vertex scalar array)?
>>>
>>> 2.  Is there a way with a theme to set a lookup table that's been built
>>> separately (rather than using ranges for hue, saturation, etc.) for extra
>>> control over the color map?
>>>
>>> It would be very cool if within a theme, or someplace handy like that,
>>> you
>>> could set the scalar range and the "Color Space" like when you use the
>>> Color
>>> Scale Editor in ParaView...
>>>
>>> Thanks,
>>> -Eric
>>>
>>> ------------------------------------------------------
>>> Eric E Monson
>>> Duke Visualization Technology Group
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>>
>>
>>
>> --
>> Jeff Baumes, Ph.D.
>> R&D Engineer, Kitware Inc.
>> (518) 371-3971 x132
>> jeff.baumes at kitware.com
>
>



-- 
Jeff Baumes, Ph.D.
R&D Engineer, Kitware Inc.
(518) 371-3971 x132
jeff.baumes at kitware.com