Yes, that sounds very sensible! Of course, the difficult part (for me, a relative noob) is to actually implement those steps in terms of a Paraview pipeline. Or would you recommend creating a new custom filter?
Unfortunately experimentation has been difficult because of the slowness / instability of the ParticleTracer filter. Even with a very modest number of particles (~10), I experience crippling delays when advancing timesteps. Perhaps pre-generating the trajectories is the answer. Thanks a lot for your suggestions. -Ryan On Tue, Jan 14, 2014 at 3:32 PM, Berk Geveci <berk.gev...@kitware.com>wrote: > I got it. I think that the correct way of doing this would be: > > 1. Seed particles > 2. Integrate 1 time step > 3. Kill particles that are older that threshold > 4. Connect particles to generate streaklets > 5. If time step % n == 0, update seed source randomly > 6. Go to 1 if time step left > > Does this make sense? > > -berk > > > On Tue, Jan 14, 2014 at 3:17 PM, Ryan Abernathey > <ryan.abernat...@gmail.com> wrote: > > Berk, > > That might be the correct interpretation for the first video, which I > think > > uses a steady (i.e. not time-dependent) flow field. For steady flows, > > streamlines, streaklines, and trajectories are all identical. > > But if you look at the second video, I think you can see that they are > > plotting Lagrangian trajectories. My velocity data is time-dependent, so > I > > think I need the trajectories. > > -Ryan > > > > > > On Tue, Jan 14, 2014 at 2:47 PM, Berk Geveci <berk.gev...@kitware.com> > > wrote: > >> > >> Hi Ryan, > >> > >> When I look at these movies carefully, it looks like they are using > >> streaklines that are seeded for a short burst. It looks like they pick > >> a number of seeds each time step and start a streakline from each and > >> keep them active for a few time steps. Then those streaklines seem to > >> be killed eventually. It also appears as if they are playing with > >> transparency depending on the age of the streakline. Am I right? > >> > >> -berk > >> > >> On Tue, Jan 14, 2014 at 2:20 PM, Ryan Abernathey > >> <ryan.abernat...@gmail.com> wrote: > >> > Hello, > >> > > >> > I am continuing my ongoing quest to do something like this > >> > > >> > > http://earth.nullschool.net/#current/wind/isobaric/1000hPa/orthographic=267.73,5.54,350 > >> > or this > >> > http://www.youtube.com/watch?v=xusdWPuWAoU > >> > in Paraview using ***time dependent velocity vectors***. > >> > > >> > While the LIC plugin is very cool, it does something different. I > >> > followed > >> > the previous suggestion and tried to use the streamline filter: > >> > http://paraview.org/Wiki/ParaView/Custom_Filters > >> > Unfortunately that is not quite right either. > >> > > >> > The problem with the streamline filter is that it treats each timestep > >> > as > >> > completely independent and regenerates the streamlines whenever the > >> > velocity > >> > field changes. (This is the correct behavior: streamlines are defined > by > >> > the > >> > *instantaneous* flow.) > >> > > >> > What we see in those videos are truly particle trajectories. In > >> > particular: > >> > - particles are seeded randomly (in space and time) > >> > - they leave a decaying trail (sometimes called a streaklet) > >> > - the particles disappear after a short lifetime > >> > This is the combination of ingredients I need to reproduce in > paraview. > >> > > >> > The best candidate is clearly the ParticleTracer filter. However, I > have > >> > hit > >> > a serious problem: it doesn't appear that this filter is able to make > >> > the > >> > particles "die" after a temporal lifetime. Compare the v 3.3 > >> > documentation > >> > http://paraview.org/OnlineHelpCurrent/ParticleTracer.html > >> > with the current documentation > >> > > >> > > http://paraview.org/Wiki/ParaView/Users_Guide/List_of_filters#ParticleTracer > >> > In the old version, there was an option called "Termination Time" that > >> > is > >> > missing from the new version. > >> > > >> > Without such an option, the particles will never disappear, the domain > >> > will > >> > get more and more crowded, and the computational expense will grow > with > >> > time. > >> > > >> > Let me know if you have any suggestions or if you know how to > re-enable > >> > this > >> > Termination Time option. > >> > > >> > Thanks a lot, > >> > Ryan > >> > > >> > _______________________________________________ > >> > 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 ParaView Wiki at: > >> > http://paraview.org/Wiki/ParaView > >> > > >> > Follow this link to subscribe/unsubscribe: > >> > http://www.paraview.org/mailman/listinfo/paraview > >> > > > > > >
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