[vtkusers] Animation of multiple input files in VTK

Thu Jul 7 10:39:37 EDT 2011

If you have all your contours ready prior to displaying and its still
slower than PV then you may want to try a similar approach but with
mappers instead.

Another thing you may do is to decimate the surfaces, if you only care
for visual appearance.

Dominik

On Thu, Jul 7, 2011 at 1:14 PM, Tijmen Klein <T.R.Klein at student.rug.nl> wrote:
> I (think that I) am allready precomputing the marching cubes. See my code
> snippet below, I think this would mean that the marching cubes are
> pre-calculated and can be cached?
> for(int i = 0; i < numberOfFrames; ++i)
> {
> reader[i] = vtkSmartPointer<vtkStructuredPointsReader>::New();
> std::stringstream name;
> name << "C:/Temp/vtk/FTLE" << (i+1) << ".vtk";
> cout << "Loading: " << name.str();
> reader[i]->SetFileName(name.str().c_str());
> reader[i]->Update();
> cout << ", and calculating ISO surface\n";
> // Create surfaces between range specified
> contours[i] = vtkSmartPointer<vtkMarchingCubes>::New();
> contours[i]->GenerateValues(10, minValue, maxValue);
> contours[i]->ComputeNormalsOn(); // fancy and expensive
> contours[i]->ComputeScalarsOn();
> contours[i]->SetInputConnection(reader[i]->GetOutputPort());
> contours[i]->Update();
> }
> On Thu, Jul 7, 2011 at 1:04 PM, Dominik Szczerba <dominik at itis.ethz.ch>
> wrote:
>>
>> > When I load this sequence in Paraview, it is able to run very smoothly
>> > (after the first run, which takes some time) while still allowing the
>> > user
>> > to interact. Does anyone know how Paraview does this?
>>
>> Probably by caching. Why not precompute marching cubes prior to rendering?
>>
>> Dominik
>>
>> >
>> > Tijmen
>> >
>> > On Wed, Jul 6, 2011 at 5:46 PM, Shashwath T.R. <trshash at gmail.com>
>> > wrote:
>> >>
>> >> Why not have multiple vtkMarchingCubes instances - one for each input,
>> >> and
>> >> then multiple mapper/actor sets? You could select which one you want to
>> >> work
>> >> on, and make the rest invisible...
>> >> Shash
>> >>
>> >> On Wed, Jul 6, 2011 at 4:37 PM, Tijmen Klein <T.R.Klein at student.rug.nl>
>> >> wrote:
>> >>>
>> >>> This is what I do. I set up the whole scene, load in all the different
>> >>> readers, and connect the first reader to the vtkMarchingCubes. Then I
>> >>> use a
>> >>> timer that calls an update function every second. This update function
>> >>> sets
>> >>> the inputconnection of the vtkMarchingCubes to the current reader
>> >>> (contours->setInputConnection(reader[current]->getOutputPort()). This
>> >>> is
>> >>> working, but results in small (but very noticable) hickups in the
>> >>> interaction. I think this is because the isosurfaces have to be
>> >>> re-calculated every time. That's why I think that I will need an array
>> >>> of
>> >>> vtkMarchingCubes too.
>> >>>
>> >>> Tijmen
>> >>>
>> >>> On Wed, Jul 6, 2011 at 11:02 AM, Dominik Szczerba
>> >>> <dominik at itis.ethz.ch>
>> >>> wrote:
>> >>>>
>> >>>> You should update your reader only from a callback function once you
>> >>>> have your scene/camera/etc set up...
>> >>>>
>> >>>> Dominik
>> >>>>
>> >>>> On Wed, Jul 6, 2011 at 10:51 AM, Tijmen Klein
>> >>>> <T.R.Klein at student.rug.nl>
>> >>>> wrote:
>> >>>> > Thank you for the reply. First of all, I'm not trying to export a
>> >>>> > animation;
>> >>>> > it should be realtime and allowing the user to navigate the scene.
>> >>>> >
>> >>>> > I'm currently applying the fist technique (update the reader in a
>> >>>> > loop).
>> >>>> > Technically this works fine, but it is really slow and also blocks
>> >>>> > the
>> >>>> > mean
>> >>>> > thread of the program (the program simply freezes when switching
>> >>>> > between 2
>> >>>> > frames). A possible solution that I came up with is the following:
>> >>>> > create N
>> >>>> > pipelines (up to the mapper), where N is the number of frames. This
>> >>>> > mean I
>> >>>> > can load the data first, create the isosurfaces and then based on
>> >>>> > the
>> >>>> > current time let the actor point to the corresponding mapper. This
>> >>>> > would
>> >>>> > mean that all the calculations are already completed.
>> >>>> >
>> >>>> > Is this a viable solution? It feels a bit hack-ish to do it like
>> >>>> > this.
>> >>>> >
>> >>>> > Tijmen
>> >>>> >
>> >>>> > On Tue, Jul 5, 2011 at 4:00 PM, Dominik Szczerba
>> >>>> > <dominik at itis.ethz.ch>
>> >>>> > wrote:
>> >>>> >>
>> >>>> >> There are a few possibilities. The simplest would be to update the
>> >>>> >> reader in a loop and dumping screen renderings. More sophisticated
>> >>>> >> would be to import them first into a temporal dataset and then
>> >>>> >> request
>> >>>> >> a specific time value.
>> >>>> >>
>> >>>> >> Dominik
>> >>>> >>
>> >>>> >> On Tue, Jul 5, 2011 at 2:57 PM, Tijmen Klein
>> >>>> >> <T.R.Klein at student.rug.nl>
>> >>>> >> wrote:
>> >>>> >> > I'm trying to animate multiple input files. These files are in
>> >>>> >> > the
>> >>>> >> > legacy
>> >>>> >> > VTK format (.vtk), and named filename[x].vtk, where [x] is an
>> >>>> >> > integer. A
>> >>>> >> > contourfilter is used to generate isosurfaces, and these
>> >>>> >> > isosurfaces
>> >>>> >> > should
>> >>>> >> > be animated.
>> >>>> >> >
>> >>>> >> > This is behaviour that is quite easy to achieve in Paraview
>> >>>> >> > (open
>> >>>> >> > the
>> >>>> >> > files,
>> >>>> >> > apply contour filter, choose a frame or click play). How can
>> >>>> >> > something
>> >>>> >> > similar be achieved in VTK? It should be possible to create a
>> >>>> >> > time-dependent
>> >>>> >> > animation, but also manually set the current frame. I thought of
>> >>>> >> > creating
>> >>>> >> > multiple InputReaders, and have the 'current' reader's
>> >>>> >> > outputport
>> >>>> >> > connected
>> >>>> >> > to the input port of the contour filter. But I think this would
>> >>>> >> > not
>> >>>> >> > be
>> >>>> >> > very
>> >>>> >> > efficient, since it's not possible to cache the results in this
>> >>>> >> > way.
>> >>>> >> > This
>> >>>> >> > would mean that all the calculations happen again when the
>> >>>> >> > animations
>> >>>> >> > restarts from frame 1. What would be a better solution?
>> >>>> >> >
>> >>>> >> > Cheers,
>> >>>> >> > Tijmen
>> >>>> >> >
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>> >>>> >
>> >>>
>> >>>
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