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 >> > > > _______________________________________________ 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