[vtkusers] Stretch/deform surface

[Miguel Ángel Rodríguez Florido]

	If you know the points (or regions) or you can choose them, you could 
try vtkWeightedTransformFilter

http://www.vtk.org/doc/release/5.0/html/a02205.html

	I hope to help.
	Best

Karthik Krishnan escribió:
> Marius Erdt wrote:
>> Hi,
>>
>> I'd like to manually deform a polyData surface, i.e. I set two mouse 
>> positions and I want a part of the surface to be stretched in the 
>> direction given by the vector between the points (just like what is 
>> possible in CAD programs).
>>
>> I've tried to use the vtkThinPlateSplineTransform on the surface, but 
>> this has a very global effect on the model. That means, the whole 
>> surface is translated in the given direction, instead of just a small 
>> neighborhood.
> The Kernel splines, one of which is the Thin plate spline (Thin Plate, 
> Thin Plate R2LogR) have infinite support. You can change the decay, but 
> it will still have a non-zero deformation at an infinite distance from 
> the center.
> 
> You might want to consider BSpline transforms for your purpose. They are 
> local in support and you can define the locality (number of nodes).
> 
> VTK does not have a BSpline implementation, but ITK does. You can use 
> the method
> 
>  itk::BSplineTransform< double, 3, 3 >::TransformPoint(..)
> 
> and iterate over each point in your polydata.
> 
> 
> -- 
> Karthik Krishnan
> R & D Engineer,
> Kitware Inc,
> Ph: +1 518 3713971 x119
> Fax: +1 518 3714573
> 
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-- 
Miguel Angel Rodriguez Florido
Center for Technology in Medicine-ULPGC-Gran Canaria-CanaryIslands,Spain
Emails:marf@{ctm.ulpgc.es,bwh.harvard.edu}-http://www.ctm.ulpgc.es/~marf
Tfnos:+34 928 451253, +34 928 452956 - Fax:+34 928 451243