[vtkusers] vtkCutClosedSurface

[sebastian ordas]

Hello David,

vtkClipClosedSurface does exactly what I need

http://ScrnSht.com/jyutyz
http://ScrnSht.com/kwanbu

except that I need the yellow triangulation only ...

What would you advice? adding to vtkClipClosedSurface the possibility of 
getting the "yellow cap" only or writing a vtkCutClosedSurface filter 
class for that single operation?

btw, isn't it possible to pipeline vtkThreshold to vtkClipClosedSurface 
somehow?

thank you,
sebastian

On 10/07/2011 03:20 PM, David Gobbi wrote:
> I can't remember the details of how to apply constraints with
> vtkDelaunay2D, but it definitely can be done.
>
>   - David
>
>
> On Fri, Oct 7, 2011 at 10:35 AM, sebastian ordas
> <sebastian.ordas at gmail.com>  wrote:
>> Hi David,
>>
>> sorry, my mistake
>> I had a copy and paste typo in one of my actors:
>> actor->SetScale(1.01,1.01,1.01);
>>
>> I tested vtkDelaunay2D. It looks pretty stable but I would like to avoid
>> meshing the holes and outside the contour:
>> http://ScrnSht.com/grcbwa
>>
>> For the former, I guess I need to use "SetSourceConnection" right?
>> But how to avoid the latter?
>>
>> best regards,
>> sebastian
>>
>>
>> On 10/7/2011 12:00 PM, David Gobbi wrote:
>>> Hi Sebastian,
>>>
>>> The filter does not move any points in the mesh (it just adds/removes
>>> points).  Check the transform matrices for your actors, from the
>>> picture it looks more like a scale difference than a shift but it is
>>> hard to tell.
>>>
>>>   - David
>>>
>>>
>>> On Fri, Oct 7, 2011 at 7:42 AM, sebastian ordas
>>> <sebastian.ordas at gmail.com>    wrote:
>>>> Thank you David!
>>>>
>>>> btw, using vtkClipClosedSurface, I´m getting a small shift between the
>>>> original mesh and the closed clipped surface
>>>> http://ScrnSht.com/byxsiw
>>>>
>>>> Is that a visualization issue only?
>>>>
>>>> regards,
>>>> sebastian
>>>>
>>>>
>>>> On 10/7/2011 3:06 AM, David Gobbi wrote:
>>>>> On Thu, Oct 6, 2011 at 4:06 PM, sebastian ordas
>>>>> <sebastian.ordas at gmail.com>      wrote:
>>>>>> Dear VTK developers,
>>>>>>
>>>>>> Following the explanation in
>>>>>> http://www.vtk.org/Wiki/VTK/Closed_Surface_Clipping
>>>>>> I was wondering about the current development state of the
>>>>>> vtkCutClosedSurface class or a similar one.
>>>>> It has not been written.  Eventually I might need it, and when I do,
>>>>> I'll write it... but that could be in a few months, a few years, or
>>>>> never.
>>>>>
>>>>>> I´m basically needing the meshing of a contour, possibly with holes,
>>>>>> but
>>>>>> always closed.
>>>>> You can use vtkDelaunay2D for that, but be warned that some inputs
>>>>> will cause vtkDelaunay2D to segfault (it is rare, but it does happen
>>>>> occasionally).
>>>>>
>>>>>> I found this interesting:
>>>>>>
>>>>>>
>>>>>> http://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf
>>>>> That method is very similar to the one that vtkClipClosedSurface uses.
>>>>> It is messy but it is robust.  The fastest triangulation methods are
>>>>> randomized Delaunay methods, but they are very sensitive to roundoff
>>>>> error, and as a result it is hard to write a robust Delaunay algorithm.
>>>>>
>>>>>> Does anyone know a workaround (has to be fast, for a real time
>>>>>> application)
>>>>>> with existing VTK classes?
>>>>> For now, vtkDelaunay2D is the only class for doing triangulations with
>>>>> holes.
>>>>>
>>>>>   - David
>>