[vtkusers] Simple question about VTK pipeline and performance

[Greg Scott]

I am still new to VTK, and I was hoping someone could clarify a simple question for me:

Imagine a simple pipeline A:

     polyReader -> smoothFilter -> polyDataNormals -> polyMapper -> myActor -> renderer

and I only do operations on the actor to adjust the orientation and position of the model.

A second pipeline B is identical, but with an additional vtkThinPlateSplineTransform filter which is currently set up by doing:

        tps = new vtkThinPlateSplineTransform();
        ...        
     
        warpFilter = new vtkTransformPolyDataFilter();
        warpFilter.SetInput((vtkPolyData)myActor.GetMapper().GetInputAsDataSet());

In 50% of circumstances, I do not need to use the deformation of the thin plate spline transform, that is, its source and target points will be identical. The only operations in this case will be the aforementioned actor functions.

Q. Do I incur any extra cost of renderering time because of the presence of the deformation filter, even though it is never updated?
Q. If so, is there a way to enable/disable the filter, without removing it from the pipeline, such that the cost is avoided, and zero deformation is ensured?

Many thanks for your help everyone.
Greg
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