[Paraview] Can you use bands in colour maps?

[Joe Borġ]

Hi David,

Thanks for the reply.  I got the desired effect with the "Use Discrete
Colors" method.

I'll look forward to the later release with the discrete maps.

Cheers,
Joe



Regards,
Joseph David Borġ
http://www.jdborg.com


On 7 November 2012 00:46, David Thompson <david.thompson at kitware.com> wrote:

> Hi Joe,
>
> > By default, all the colour maps in ParaView are continuous between
> points.  I'd like to have only one colour in between points I set in the
> XML map, is this possible?
>
> In the current release of ParaView, you can click on the "Edit color map"
> button in the toolbar and turn on "Use Discrete Colors" in the color
> editor. By changing the number of colors with the neighboring slider,
> uniform ranges of scalar values will be assigned a single color.
>
> In an upcoming release, discrete color maps will be available. Discrete
> colormaps do not interpolate colors; instead they are looked up in a table,
> so a single large difference in values will not force any small variations
> to be lumped into a single color band. However, this requires your scalar
> field to take on a small number of distinct values (32 or fewer); colors
> are assigned to a single value, not a range.
>
> To map non-uniform ranges of values to a single color each, you really
> should create a derived, integer-valued variable and use it for coloring --
> regardless of whether you use continuous colormaps in the current release
> or plan to use categorical color maps later. The calculator filter's floor,
> ceil, and round functions might be worth a try in creating the derived
> field; if there's not a simple expression to convert each range of interest
> to an integer, the Python calculator will let you apply a tabular function.
>
> Finally, it *may* also be possible to achieve what you desire with a
> custom XML color map by placing control points with different colors very
> close to each other to create a discontinuous color map. This would be
> difficult to adjust in the color editor should the control points need to
> be repositioned, but might be the easiest thing to do if the bands are
> fixed values or fixed fractions of the total range.
>
>         David
>
>
>
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