[Paraview] Selection of points

[John Biddiscombe]

Eric

No. My particles already have a global Id which I use to track them 
independently. The trouble is (was), that when you select some in 
ParaView, it uses their Id taken from the index they have in the 
vtkPoints list (or Cell Id if using verts) and noy my "ParticleId" 
array. This order can change arbitrarily in my data. As time steps 
change - the selected points constantly shift about.

I fixed the problem by creating a vtkSnapshot filter which simply 
captures a dataset when you create it. It caches the result and never 
updates anything from then on. This way I can select a bunch of 
particles using the mouse, copy the active selection, then snapshot it. 
I then pass this into the TTemporalTrails filter as the selction input 
(you might need to update your copy to get this filter). I can now pick 
individual (or groups) of particles at time T=large, capture them, go 
back to T=0 and draw pathlines only for thos eI wanted. Nice. This is 
also handy because particles can be injected at differnt times and if 
their Id doesn't exist at some T value, the trails filter just skips 
them. The ones selected get drawn - if they exist.

JB

> Hey John,
>
> I'm trying to make sure I understand your question -- would your 
> problem be solved if your particles had a Global ID associated with 
> them, which was a unique "tag" that didn't change over time? (Then, 
> the selection type could be "global id" and shouldn't reorder when 
> time is stepped back to zero.)
>
> I've had to add a Global ID assignment to my version of the Xdmf 
> reader so that my animated particle data could be selected and have 
> attributes plotted over time, etc.
>
> Talk to you later,
> -Eric
>
> ------------------------------------------------------
> Eric E Monson
> Duke Visualization Technology Group
>
>
>
> On Jul 22, 2008, at 3:46 AM, John Biddiscombe wrote:
>
>> I have a dataset which consists of animating particles. I can select 
>> a region of space and get the Id's of certain particles. I now wish 
>> to pass this list back into my Pathline filter so that only the 
>> particles selected are drawn with pathlines. However, when I hit the 
>> back button for the animation to return to time zero, the selected 
>> particles now change. I can change the selection type to Id - which 
>> is great because I can use this information directly in the pathline 
>> filter to pick out the lines, but again - when I change time step, 
>> the particles are re-ordered and my information is lost.
>>
>> I'd like to copy the active selection - and then fix it - so it is 
>> now disconnected from the pipeline and becomes a static piece of data 
>> which does noit change with time.  If I save the selction to disk, I 
>> can load it and use it as I'd like to. Is there a way of copying the 
>> active selection - and disconnecting it from the pipeline so that I 
>> can skip the disk save/load stage and pass the selection directly to 
>> my pathline filter?
>>
>> thanks
>>
>> JB
>>
>> -- 
>> John Biddiscombe,                            email:biddisco @ cscs.ch
>> http://www.cscs.ch/about/BJohn.php
>> CSCS, Swiss National Supercomputing Centre  | Tel:  +41 (91) 610.82.07
>> Via Cantonale, 6928 Manno, Switzerland      | Fax:  +41 (91) 610.82.82
>>
>>
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>


-- 
John Biddiscombe,                            email:biddisco @ cscs.ch
http://www.cscs.ch/about/BJohn.php
CSCS, Swiss National Supercomputing Centre  | Tel:  +41 (91) 610.82.07
Via Cantonale, 6928 Manno, Switzerland      | Fax:  +41 (91) 610.82.82