[vtkusers] Question about color mapping due to scalar(s) in VTK

[David Doria]

On Thu, Jul 12, 2012 at 3:53 PM, Alex Malyushytskyy
<alexmalvtk at gmail.com> wrote:
> It there any reason VTK does not provide vtkDataSetAttributes specific
> to data set,
> but it has to be only only nodal or cell data?
>
> Assume you need to color data according to the nodal or cell scalar in VTK.
> This can be specified on the dataset level if you construct proper pipeline.
>
> But when you have  a single variable stored with dataset (for example polydata )
> you need work directly with actor.
>
> Yes, I it is possible to store custom variable  with dataset, then
> build look up table and then set appropriate color to each actor,
> but it is way less convenient and require usage of different
> approaches in the same application
> if you need to switch between  showing scalars  per-cell (or per-node)
> and per-data set, depending on the user need.
>
> This makes sense not only in color definition.
> For example you might be interested in velocity of the center mass of
> the object ( single point ) in one case, when in the other cases
> you might want velocity at each node of the dataset,
>
> Adding support of scalar(s) attached to dataset itself, seems logical
> way to go, so I am wondering was there any reason not to implement it
> ( besides  time).


I believe what you are looking for is "Field Data":
http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/FieldData

David