[Paraview] Streamtracer filter

[Karla Vega]

Hi Berk,

Thank you so much for replying. I've uploaded pictures, movies and data to: (see description below)

www.tacc.utexas.edu/~vega/Blood_Flow

The movies and pictures are under "Vis". I also have uploaded 25 timesteps to "Data".
We've seeding streamlines were the velocity field was the highest. We used point-cloud and we noticed that some of the streamlines end at the walls and some just stop at some points as you can see from the pictures. We worked for a while on seeding the streamlines correctly and using different integrators and step sizes, but nothing seemed to work (although it did look better when we seeded streamlines at the highest velocity points).
The computer we are using is a Linux (Red hat) Dell Precision 670 Mini-Tower 3.60GHz, XEON Processor w/ 2MBL2 Cache with 8 GB in memory. The paraview version we are using is 2.4.2 64 bit.

I also wanted to ask you about the blending that Paraview uses. As you can see from the pictures, objects in the back are not being blended correctly. Is there a way to fix this?
Maybe changing the rendering to be back-to-front instead of front-to-back?


Thank you again for all your help!

Karla Vega
vega at tacc.utexas.edu


Description:

"Patient-specific abdominal aorta"

"Fluid-structure interaction is calculated for a patient-specific abdominal aorta of a healthy over-55 volunteer obtained from a 64-slice CT angiography. A periodic flow waveform is applied at the inlet of the aorta, while resistance boundary conditions are applied at all outlets. The computational mesh consists of 52,420 quadratic NURBS elements, and the output of the simulation includes pressure and velocity fields. The entire time series of data is approximately 500MB."

Karla Vega
Email: vega at tacc.utexas.edu
Work: (512) 232-4772
Mobile: (512) 577-8723



-----Original Message-----
From: Berk Geveci [mailto:berk.geveci at gmail.com]
Sent: Mon 7/3/2006 8:28 AM
To: Karla Vega
Cc: paraview at paraview.org
Subject: Re: [Paraview] Streamtracer filter
 
Hi Karla,

Can you be more specific? Maybe post some screenshots and data? That filter
has been quite thoroughly tested on single processor. I also fixed a few
bugs that were in the parallel implementation. Depending on your ParaView
version, you might not have the fixes for the parallel version. I would be
surprised if the integration algorithm itself has a bug. Of course, there
are always numerical accuracy issues and you can compensate by using a
different integrator or adjusting the step-size (the default is Runge-Kutta
2, I believe). Known issues are:

* Premature ending of streamlines in C-grids where the grid folds onto
itself (this may be what you are seeing)
* Premature ending of streamlines in singlular cells

I also need to check a bug report that reads "Streamlines wrong for uniform
rectilinear data... You would expect a streamline to form a circle around
the X axis, but what you get is a streamline that seems to go in completely
the wrong direction. The problem only seems to happen in rectilinear
data.  If you convert to an unstructured grid (with Clean to Grid), the
streamline appears as expected.".  I am guessing it is a bug in the voxel
cell type. I will check this bug and fix it if necessary in next few weeks.

-Berk


On 6/30/06, Karla Vega <vega at tacc.utexas.edu> wrote:
>
>  Hello everyone,
>
> I've been having difficulties with the streamtracer filter. It seems to be
> integrating the velocity field incorrectly and some of my streamlines will
> not continue where they are suppose to do so. I've read through the
> vtkStreamTracer.h file to learn about the different inputs, but it still
> doesn't show the streamlines completely.
> Does anyone know of any known issues with this filter?
>
> Thank you again,
>
> Karla
>
> _______________________________________________
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> ParaView at paraview.org
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>
>

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