[vtkusers] slice structured grid with polydata

[Cory Quammen]

What do you want as output instead?

On Thu, Mar 24, 2016 at 10:53 AM, Justin Weber <onlyjus at gmail.com> wrote:
> I didn't realize this earlier but the vtkClipDataSet tetrahedralizes the
> mesh before slicing? It seems that this is required for the algorithm. Do
> you know of any ways to prevent this?
>
> BTW, here is the link to the example:
> http://www.vtk.org/Wiki/VTK/Examples/Python/Meshes/vtkClipDataSetWithPolydata
>
> Justin
>
> On Mon, Mar 7, 2016 at 5:30 PM, Cory Quammen <cory.quammen at kitware.com>
> wrote:
>>
>> That's great, Justin. Thanks for reporting back.
>>
>> Cory
>>
>> On Mon, Mar 7, 2016 at 4:04 PM, Justin Weber <onlyjus at gmail.com> wrote:
>>>
>>> Cory,
>>>
>>> Thanks for your help. I got it working! I might put the code up as an
>>> example.
>>>
>>>
>>> Justin
>>>
>>> On Thu, Feb 18, 2016 at 10:58 PM, Cory Quammen <cory.quammen at kitware.com>
>>> wrote:
>>>>
>>>> Justin,
>>>>
>>>> There is nothing canned in VTK to do this, but with some work you should
>>>> be able to get there using an implicit function created from your STL file.
>>>> At a high level, what you would do is create an instance of
>>>> vtkImplicitPolyDataDistance. Set its input to the poly data from the STL
>>>> file. Then, create a new point data array in your structured grid that
>>>> stores the value from the implicit poly data distance filter. Negative
>>>> values will be inside the poly data, positive values outside, and 0 at the
>>>> surface. Finally, use vtkClipDataSet to clip the structured grid a function
>>>> value 0. This should give you back an unstructured grid in approximately the
>>>> shape of your input STL. It won't be exact because of the interpolation used
>>>> by vtkClipDataSet, but it should be close.
>>>>
>>>> Hope that helps.
>>>>
>>>> Cory
>>>>
>>>> On Thu, Feb 18, 2016 at 10:08 PM, Justin Weber <onlyjus at gmail.com>
>>>> wrote:
>>>>>
>>>>> I would like to generate a "cutcell" mesh using vtk by slicing a
>>>>> structured grid with polydata loaded from a STL file. The resulting mesh
>>>>> would be an unstructured grid.
>>>>>
>>>>> Are there any tools in vtk to accomplish this?
>>>>>
>>>>> I can create the structured grid and polydata successfully. Now I just
>>>>> need an algorithm to slice the structured mesh with the polydata surface.
>>>>>
>>>>> In my searching I could not find anything. However, I could accomplish
>>>>> this by ray casting to find the intersections between the structured grid
>>>>> and the polydata. Then using those points to create the unstructured grid.
>>>>>
>>>>> See attached 2d sketch.
>>>>>
>>>>> Thanks!
>>>>> Justin
>>>>>
>>>>>
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>>>>
>>>>
>>>>
>>>> --
>>>> Cory Quammen
>>>> R&D Engineer
>>>> Kitware, Inc.
>>>
>>>
>>
>>
>>
>> --
>> Cory Quammen
>> R&D Engineer
>> Kitware, Inc.
>
>



-- 
Cory Quammen
R&D Engineer
Kitware, Inc.