[vtkusers] VTK time support - how good is it?

[Moreland, Kenneth]

Yes, time support is indeed this general, yes it works seamlessly with the rest of VTK, and no, there is no performance penalty when working with timesteps beyond what you would have anyway iterating over the same timesteps in some other way.  From your description of your data, it sounds like the VTK time support will do exactly what you want.

We have since written a paper for IEEE Visualization which documents the implementation.  I have added this paper to the Wiki and if you go back to the Time Support Wiki page you will see a link to download it.  If you want to see a demonstration of some of the things you can do with the time support, you can review the animation we sent with the paper.  I have that posted on my web site: http://www.cs.unm.edu/~kmorel/documents/TimeVis-IEEE2007.html

To play with this, you may consider loading your data in ParaView.  It takes advantage of the time support and will synchronize the loading of time steps based on the time stamps in the data and provides all the GUI controls to manipulate time.

-Ken


On 5/13/09 7:33 AM, "Johannes Töger" <johannes.toger at med.lu.se> wrote:

Hi!

Our research group is considering using VTK (or some higher-level library like Mayavi/TVTK) for visualization of blood flow in the heart. Data is available as three-dimensional, time-resolved velocity fields measured using Phase Contrast MRI. Additionally, we have animated anatomical slices of the heart.

All datasets are sampled over one heart beat (or a part of the heartbeat for technical reasons), but with different timesteps. For example, the velocity data might have 40 timesteps and the anatomical slices 25 or 30.

This data is inherently time-resolved, so good time support is a must. I've been reading a lot about the time support in VTK, but the only thorough description I can find is an old(?) wiki post from when it was first discussed: http://www.vtk.org/Wiki/VTK/Time_Support .

One paragraph in this article is particularly interesting:

"Playback of an animation means varying time, instead of varying timesteps. By sampling time at regular intervals, animations can play-back at the correct rate, even if the timesteps in a dataset don't represent regular intervals. When dealing with multiple datasets, the correct data can automatically be displayed, as long as the dataset timesteps share a common reference (if they don't, simple offset and scale transformations are trivial to implement and use). In the case of a single dataset, matching the animation sample points to the timesteps in the dataset can provide backwards-compatible behavior."

Now to my questions:

* Is time support indeed this general in VTK?

* Does it work seamlessly with the rest of VTK?

* Is there a performance penalty when working with timesteps? If so, how large is it?


Thank you for your attention,

Johannes Töger



   ****      Kenneth Moreland
    ***      Sandia National Laboratories
***********
*** *** ***  email: kmorel at sandia.gov
**  ***  **  phone: (505) 844-8919
    ***      web:   http://www.cs.unm.edu/~kmorel

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