[vtkusers] Help with VtkDatasetsurface filter

Wed Apr 3 21:59:31 EDT 2013

 As far as I understand if all internal surfaces were eliminated (for
example by vtkDataSetSurfaceFilter ) you would see only blue,
but I do not think vtkDataSetSurfaceFilterdoes it.

Below is only my assumption, since I did not look in the
vtkDataSetSurfaceFilter internals and documentation does not answer the
question, but I would expect that filter only combines small primitives
which are in the same geometrical plane and are connected into large and
eliminates duplicates when it works on the unstructured grid .

It the array you colored original database is transferred you will see the
same colors as with original database.

Regards,
      Alex

On Wed, Apr 3, 2013 at 7:42 AM, Bhanu Hariharan <bhanu at petrotel.com> wrote:

> Thanks Alex.
>
> However the resulting picture (full sized model) is the same. I expected
> different picture but it is not.
>
> I made outer cells all blue and in between cells all red. A transparent
> image of this grid when all cells are rendered is purple (which is expected
> blend of red and blue).
>
> But it remains the same image when I render just surface - I expect to see
> only BLUE?
> Is this a VTK bug perhaps??
>
> Thanks again.
> Bhanu
>
>
>
> On Tue, Apr 2, 2013 at 6:14 PM, Alex Malyushytskyy <alexmalvtk at gmail.com>wrote:
>
>> I was not suggesting to use VTKActor, cause it means that your
>> performance at least for large number of nodes
>> will decrease. I only said it would make a difference ( possibly from
>> very slow to slow or the same you currently have).
>>
>> As for opacity, I would expect picture be different, but I would not
>> expect human eye to see the difference.
>> Keep in mind that as far as I understand curse model only used during
>> transition or rotation, resulted picture shown is full sized model,
>>
>> Regards,
>>    Alex
>>
>>
>> On Tue, Apr 2, 2013 at 3:14 PM, Bhanu Hariharan <bhanu at petrotel.com>
>> wrote:
>> > Alex,
>> > I will try your suggestions - using VTKActor to see difference and
>> different
>> > frame rates.
>> >
>> > I have one more question that's not related to rendering performance. It
>> > concerns opacity.
>> >
>> > I was alteast expecting to see different images when I specify opacity
>> < 1
>> > for the grid.
>> >
>> > Shouldn't a transparent image look different when I render all cells
>> (all
>> > layers) than when I render just surface cells?
>> >
>> >
>> > Thanks again,
>> > Bhanu
>> >
>> >
>> >
>> >
>> > On Tue, Apr 2, 2013 at 4:49 PM, Alex Malyushytskyy <
>> alexmalvtk at gmail.com>
>> > wrote:
>> >>
>> >> LOD (level of details)  technique consists of run time assessment of
>> >> performance and building a special model which will be used in certain
>> >> circumstances and on the one hand would look as close as possible to
>> >> the original, but on another hand allows achieve desired or better
>> >> performance.
>> >> That what LOD actor does, crude models will be silently created and
>> >> displayed during rotation or when actor is moved.
>> >>
>> >> Now assume there are 2 model - lets say 1st is your unstructured grid,
>> >> another is result of dataSetSurfaceFilter.
>> >> Since both are using LOD actors, the following might happen:
>> >>
>> >> 1st model is found to be too big to be displayed and as a result crude
>> >> model with N1 number of nodes is created and displayed
>> >> 2nd model is found to be too big to be displayed and as a result crude
>> >> model with N2 number of nodes is created and displayed
>> >> or it is small enough , so it is displayed as is (but lets say still
>> >> have N2 nodes)
>> >>
>> >> Now N1 might be mostly the same as N2.
>> >> And you see no difference in performance during transition or rotation.
>> >> Basically this means that LOD actor does his job well enough.
>> >> I bet if you were using regular actors you would see a huge
>> >> performance increase.
>> >>
>> >> If you need further performance you may just specify different frame
>> rate.
>> >> From http://www.vtk.org/doc/release/4.0/html/classvtkLODActor.html:
>> >>
>> >> "To control the frame rate, you typically set the
>> >> vtkRenderWindowInteractor DesiredUpdateRate and StillUpdateRate. This
>> >> then will cause vtkLODActor to adjust its LOD to fulfill the requested
>> >> update rate.
>> >> For greater control on levels of detail, see also vtkLODProp3D. That
>> >> class allows arbitrary definition of each LOD.
>> >> "
>> >>
>> >> Hope this helps,
>> >>
>> >> Alex
>> >>
>> >>
>> >>
>> >>
>> >> On Tue, Apr 2, 2013 at 2:18 PM, Bhanu Hariharan <bhanu at petrotel.com>
>> >> wrote:
>> >> > Alex,
>> >> >
>> >> > To be specific in one of my cases,  No. of surfaces rendered were
>> >> > reduced
>> >> > from 6163542 to 373626 assuming grid has hexahedrons each with 6
>> >> > surfaces. I
>> >> > got the number 373626 by doing
>> >> >
>> >> > dataSetSurfaceFilter->GetOutput()->GetNumberOfCells()
>> >> >
>> >> > Thats a significant reduction of number of surfaces. These are
>> rendered
>> >> > using VTKLODActor.
>> >> >
>> >> > Can you please explain what you mean by "actually shown primitives
>> >> > during
>> >> > rotation". What are the shown primitives?
>> >> >
>> >> > I am just adding the output of the dataSetSurfaceFilter to a
>> >> > vtkDataSetMapper and then to a vtkLODActor.
>> >> >
>> >> > All I know if no. of surfaces are reduced. Do I need to do/check
>> >> > something
>> >> > else?
>> >> >
>> >> > If you need something specific to answer more specifically, I can
>> >> > provide
>> >> > the details. It would be a great help.
>> >> >
>> >> > Thanks,
>> >> > Bhanu
>> >> >
>> >> >
>> >> > ---------- Forwarded message ----------
>> >> > From: Alex Malyushytskyy <alexmalvtk at gmail.com>
>> >> > Date: Tue, Apr 2, 2013 at 4:03 PM
>> >> > Subject: Re: [vtkusers] Help with VtkDatasetsurface filter
>> >> > To: "vtkusers at vtk.org" <vtkusers at vtk.org>
>> >> >
>> >> >
>> >> > You may get only general advice asking general questions.
>> >> > Compare  the number of nodes/cells you are you are getting from
>> >> > vtkDataSetSurfaceFilter with
>> >> > such in the unstructured grid,
>> >> > Even though it may be significantly decreased in some cases, for
>> >> > example if LOD actors are used,  they may decrease actually shown
>> >> > primitives during rotation approximately to the same number and you
>> >> > will not see any difference in the performance.
>> >> >
>> >> > Regards,
>> >> >     Alex
>> >> >
>> >> >
>> >> > On Tue, Apr 2, 2013 at 8:27 AM, Bhanu Hariharan <bhanu at petrotel.com>
>> >> > wrote:
>> >> >> Hi All,
>> >> >> I was wondering if anyone would be kind enough to answer the
>> following
>> >> >> query
>> >> >> for me.
>> >> >>
>> >> >> I had posted this a while back and still havent found the reason why
>> >> >> vtkDataSetSurfaceFilter hasn't made rendering any faster. The
>> >> >> interaction
>> >> >> and rendering time to rotate zoom etc seem to be just the same as
>> >> >> though I
>> >> >> rendered all cells in the unstructured grid.
>> >> >> The reason I chose to introduce rendering just surface cells in the
>> >> >> first
>> >> >> place was to make rendering faster. But I am surprised it doesnt
>> make
>> >> >> any
>> >> >> difference at all :(.
>> >> >> Any words or ideas?
>> >> >>
>> >> >> Thanks so much
>> >> >> Bhanu
>> >> >>
>> >> >>
>> >> >>
>> >> >> On Mon, Mar 11, 2013 at 4:30 PM, Bhanu Hariharan <
>> bhanu at petrotel.com>
>> >> >> wrote:
>> >> >>>
>> >> >>> One related question though. I started using Surface Filter really
>> >> >>> only
>> >> >>> for performance reasons.
>> >> >>>
>> >> >>> I was thinking if I rendered just surface cells, the rendering and
>> >> >>> rotation etc would be must faster.
>> >> >>> However I do not find it any different than when I render all
>> cells.
>> >> >>> What
>> >> >>> am I missing?
>> >> >>> Any reasons anyone can think of, please let me know.
>> >> >>>
>> >> >>>
>> >> >>>
>> >> >>> Thanks,
>> >> >>> Bhanu
>> >> >>>
>> >> >>>
>> >> >>>
>> >> >>> On Mon, Mar 11, 2013 at 4:12 PM, Bhanu Hariharan <
>> bhanu at petrotel.com>
>> >> >>> wrote:
>> >> >>>>
>> >> >>>> David,
>> >> >>>> As you suggested, I got it to work using SetGlobalIds and then
>> >> >>>> retrieving
>> >> >>>> that using GetGlobalIds. Many thanks for your patience and help.
>> >> >>>>
>> >> >>>>
>> >> >>>> -Bhanu
>> >> >>>>
>> >> >>>>
>> >> >>>> On Wed, Mar 6, 2013 at 11:41 AM, Bhanu Hariharan <
>> bhanu at petrotel.com>
>> >> >>>> wrote:
>> >> >>>>>
>> >> >>>>> David,
>> >> >>>>>
>> >> >>>>> I am using vtk 5.2 - is it possible that this function was not
>> >> >>>>> defined
>> >> >>>>> in that version.
>> >> >>>>>
>> >> >>>>> I get the error that SetOriginalCellIdsName is not a member of
>> >> >>>>> vtkDataSetSurfaceFilter   :(
>> >> >>>>>
>> >> >>>>> Bhanu
>> >> >>>>>
>> >> >>>>>
>> >> >>>>>
>> >> >>>>> On Wed, Mar 6, 2013 at 10:36 AM, David E DeMarle
>> >> >>>>> <dave.demarle at kitware.com> wrote:
>> >> >>>>>>
>> >> >>>>>> Give DSF a name for the array.
>> >> >>>>>> SetOriginalCellIdsName("idsintoDSForsomething")
>> >> >>>>>> Then retrieve it from the output like
>> >> >>>>>>
>> DSF->GetOutput()->GetCellData()->GetArray("idsintoDSForsomething")
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>> David E DeMarle
>> >> >>>>>> Kitware, Inc.
>> >> >>>>>> R&D Engineer
>> >> >>>>>> 21 Corporate Drive
>> >> >>>>>> Clifton Park, NY 12065-8662
>> >> >>>>>> Phone: 518-881-4909
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>> On Wed, Mar 6, 2013 at 11:29 AM, Bhanu Hariharan
>> >> >>>>>> <bhanu at petrotel.com>
>> >> >>>>>> wrote:
>> >> >>>>>>>
>> >> >>>>>>>
>> >> >>>>>>> David,
>> >> >>>>>>>
>> >> >>>>>>> I had turned on PassThroughCell. But I do not know how to
>> access
>> >> >>>>>>> the
>> >> >>>>>>> new Ids array after the fact.
>> >> >>>>>>> VTK Doc says something about a 'OrginalCellIds' but I am not
>> sure
>> >> >>>>>>> how
>> >> >>>>>>> to access this.
>> >> >>>>>>> So I extracted the output of DSF to a vtkPolyData but still
>> cant
>> >> >>>>>>> figure out how to get to that new Ids array.
>> >> >>>>>>> Any help with that is really appreciated.
>> >> >>>>>>>
>> >> >>>>>>> I will try your other suggestion in the meantime.
>> >> >>>>>>>
>> >> >>>>>>> Thanks,
>> >> >>>>>>> Bhanu
>> >> >>>>>>>
>> >> >>>>>>>
>> >> >>>>>>> On Wed, Mar 6, 2013 at 9:25 AM, David E DeMarle
>> >> >>>>>>> <dave.demarle at kitware.com> wrote:
>> >> >>>>>>>>
>> >> >>>>>>>> Sorry for the confusion, it has been a long time since I added
>> >> >>>>>>>> that
>> >> >>>>>>>> code the DataSetSurfaceFilter. Turning
>> PassThroughCell/PointIds
>> >> >>>>>>>> in
>> >> >>>>>>>> fact
>> >> >>>>>>>> generates a new Ids array, which you can retrieve after the
>> fact
>> >> >>>>>>>> to
>> >> >>>>>>>> do the
>> >> >>>>>>>> lookups into the data that is input to the DSF and extract
>> >> >>>>>>>> particular
>> >> >>>>>>>> cells/points by their offset (n'th cell in the cell array,
>> n'th
>> >> >>>>>>>> point in the
>> >> >>>>>>>> point array)
>> >> >>>>>>>>
>> >> >>>>>>>> However I still recommend making your own ids array and using
>> >> >>>>>>>> that
>> >> >>>>>>>> instead of PassThrough. vtkIdFilter will generate them for
>> you.
>> >> >>>>>>>> The
>> >> >>>>>>>> array
>> >> >>>>>>>> marked as the active global ids array is treated specially by
>> >> >>>>>>>> most
>> >> >>>>>>>> filters
>> >> >>>>>>>> in that they try to preserve it across operations (including
>> >> >>>>>>>> threshold and
>> >> >>>>>>>> DSF). We added this to VTK a few years ago specifically for
>> this
>> >> >>>>>>>> case of
>> >> >>>>>>>> finding out where particular result values come from (and in
>> >> >>>>>>>> particular for
>> >> >>>>>>>> surface selection). So the Threshold and surface filter will
>> push
>> >> >>>>>>>> globalIDS
>> >> >>>>>>>> forward just fine. Once you get a result, grab the active
>> >> >>>>>>>> globaIDs
>> >> >>>>>>>> array,
>> >> >>>>>>>> look for the values in it, and look them up in the original
>> data.
>> >> >>>>>>>> The
>> >> >>>>>>>> extract selections filter will do the job of looking them up
>> in
>> >> >>>>>>>> the
>> >> >>>>>>>> original
>> >> >>>>>>>> data and pulling them out as a new dataset.
>> >> >>>>>>>>
>> >> >>>>>>>>
>> >> >>>>>>>> David E DeMarle
>> >> >>>>>>>> Kitware, Inc.
>> >> >>>>>>>> R&D Engineer
>> >> >>>>>>>> 21 Corporate Drive
>> >> >>>>>>>> Clifton Park, NY 12065-8662
>> >> >>>>>>>> Phone: 518-881-4909
>> >> >>>>>>>>
>> >> >>>>>>>>
>> >> >>>>>>>> On Wed, Mar 6, 2013 at 10:02 AM, Bhanu Hariharan
>> >> >>>>>>>> <bhanu at petrotel.com>
>> >> >>>>>>>> wrote:
>> >> >>>>>>>>>
>> >> >>>>>>>>> David,
>> >> >>>>>>>>> Thanks for replying. However I have a doubt.
>> >> >>>>>>>>> Are you suggesting the VTKUnstructuredgrid should have an
>> >> >>>>>>>>> globalids
>> >> >>>>>>>>> array? Is that what the member is called - globalIds? I
>> actually
>> >> >>>>>>>>> pass
>> >> >>>>>>>>> VTKUnstructuredgrid  to a VTKThreshold filter and then pass
>> that
>> >> >>>>>>>>> filter to
>> >> >>>>>>>>> VTKdatasetsurfacefilter.
>> >> >>>>>>>>>
>> >> >>>>>>>>> Perhaps you can post a couple lines of code. That would be
>> very
>> >> >>>>>>>>> helpful.
>> >> >>>>>>>>> Thanks,
>> >> >>>>>>>>> Bhanu
>> >> >>>>>>>>>
>> >> >>>>>>>>>
>> >> >>>>>>>>>
>> >> >>>>>>>>> On Tue, Mar 5, 2013 at 6:55 PM, David E DeMarle
>> >> >>>>>>>>> <dave.demarle at kitware.com> wrote:
>> >> >>>>>>>>>>
>> >> >>>>>>>>>> The input data should have a globalids array containing a
>> >> >>>>>>>>>> unique
>> >> >>>>>>>>>> value for each cell. If it does, extract will preserve it.
>> >> >>>>>>>>>> After
>> >> >>>>>>>>>> the
>> >> >>>>>>>>>> extraction, use that array in the polydata to do the look
>> up to
>> >> >>>>>>>>>> the original
>> >> >>>>>>>>>> cell in the unstructured grid.
>> >> >>>>>>>>>>
>> >> >>>>>>>>>> On Mar 5, 2013 6:00 PM, "Bhanu Hariharan" <
>> bhanu at petrotel.com>
>> >> >>>>>>>>>> wrote:
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Hi All,
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> I need some help doing the following. Please could one of
>> you
>> >> >>>>>>>>>>> guide me on how.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> I use a vtkDataSetSurfaceFilter on VTKUnstructuredGrid to
>> >> >>>>>>>>>>> render
>> >> >>>>>>>>>>> skin of that grid. That works fine and I can see the
>> number of
>> >> >>>>>>>>>>> surfaces
>> >> >>>>>>>>>>> shown by grabbing the
>> >> >>>>>>>>>>> dataSetSurfaceFilter->GetOutput()->GetNumberOfCells().
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> I need a way to map the surface back to the original cell
>> id.
>> >> >>>>>>>>>>> That
>> >> >>>>>>>>>>> is if I have 2 cells and I render just skin, number of
>> >> >>>>>>>>>>> surfaces
>> >> >>>>>>>>>>> rendered are
>> >> >>>>>>>>>>> 10. I need to be able to pick on any of these 10 surfaces
>> and
>> >> >>>>>>>>>>> map
>> >> >>>>>>>>>>> them back
>> >> >>>>>>>>>>> to either of the the 2 grid cells.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> http://www.vtk.org/doc says :
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> If PassThroughCellIdsOn is 1, then the output polygonal
>> >> >>>>>>>>>>> dataset
>> >> >>>>>>>>>>> will have a celldata array that holds the cell index of the
>> >> >>>>>>>>>>> original 3D cell
>> >> >>>>>>>>>>> that produced each output cell. This is useful for cell
>> >> >>>>>>>>>>> picking.
>> >> >>>>>>>>>>> I turned the PassThroughCellIds On and I have UseStrips
>> turned
>> >> >>>>>>>>>>> off.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Then I did
>> >> >>>>>>>>>>> vtkPolyData *surfacePolyData =
>> >> >>>>>>>>>>> dataSetSurfaceFilter->GetOutput();
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> But I do not see how I can access that celldata array that
>> >> >>>>>>>>>>> holds
>> >> >>>>>>>>>>> the original 3D cells for the surfaces.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Please can anyone advise on how.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Thanks in advance.
>> >> >>>>>>>>>>> Bhanu
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> _______________________________________________
>> >> >>>>>>>>>>> Powered by www.kitware.com
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Visit other Kitware open-source projects at
>> >> >>>>>>>>>>> http://www.kitware.com/opensource/opensource.html
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Please keep messages on-topic and check the VTK FAQ at:
>> >> >>>>>>>>>>> http://www.vtk.org/Wiki/VTK_FAQ
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Follow this link to subscribe/unsubscribe:
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>> >> >>>>>>>>>>>
>> >> >>>>>>>>>
>> >> >>>>>>>>
>> >> >>>>>>>
>> >> >>>>>>
>> >> >>>>>
>> >> >>>>
>> >> >>>
>> >> >>
>> >> >>
>> >> >> _______________________________________________
>> >> >> Powered by www.kitware.com
>> >> >>
>> >> >> Visit other Kitware open-source projects at
>> >> >> http://www.kitware.com/opensource/opensource.html
>> >> >>
>> >> >> Please keep messages on-topic and check the VTK FAQ at:
>> >> >> http://www.vtk.org/Wiki/VTK_FAQ
>> >> >>
>> >> >> Follow this link to subscribe/unsubscribe:
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>> >> >>
>> >> > _______________________________________________
>> >> > Powered by www.kitware.com
>> >> >
>> >> > Visit other Kitware open-source projects at
>> >> > http://www.kitware.com/opensource/opensource.html
>> >> >
>> >> > Please keep messages on-topic and check the VTK FAQ at:
>> >> > http://www.vtk.org/Wiki/VTK_FAQ
>> >> >
>> >> > Follow this link to subscribe/unsubscribe:
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>> >
>> >
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the VTK FAQ at:
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>>
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