[FLASH-USERS] 3D visualization, also Visit issues

Tomasz Plewa tplewa at fsu.edu
Sat Apr 11 23:11:33 EDT 2009


Dennis -

Have you tried to report your problems on the visit users forum? For 
more information please consult visitusers.org.

I do not know of a better freely available visualization and data 
analysis tool, especially given the amount of development and support 
involved.

Tomek
--
D.F. Duffin wrote:
> Hello everyone,
>
> So, I'm getting headaches going through many different visualization
> programs, most needing modifications to handle FLASH (I use FLASH2.5).
>  If anyone has any program recommendations, I'm all ears.  For now,
> VisIt is my 3D preference (has anyone ever tried to do stuff 3D with
> IDL?).
>
> VisIt has by far the best 3D surfaces, and has very good features,
> especially for animations.  However, being that it is by far and away
> the only choice for 3D visuals, I have some serious concerns (I've
> included images of the problems below).  Perhaps someone here has found
> some solutions (I've also tried the visit mailing list):
>
> 1) minor, but most quantities have to be scaled for features to work
> (e.g. distances if distances are small, some surfaces turn black.  If
> your vector field or distances are to small, vector and streamline will
> not work.  This is because VisIt is single precision, still.  The fix
> is to scale things.  But then, what units will graphs show?
>
> 2) 3D surface over multiple refinement levels will cut out grid like
> features in the surface (ghost cells?).  A fix that sometimes works
> (hardly ever for me) is that you isolate the refinement levels that are
> important for that surface.  However, if your surface is on two
> different levels, you're screwed.  You would think there is a way to
> fix this...anyone? 
>
> 3)  3D streamlines:  If I plot up a magnetic field, my streamlines will
> be drawn for each refinement level.  The result is a set of field lines
> per starting point with varying degrees of accuracy.  Magnetic field
> lines (in my problems) are always living on several if not more
> refinement levels per visual, so avoiding multiple levels is
> impossible.  Even if I wanted to, the streamline plot will not allow me
> (I receive an error, improper pipeline use or something like that). 
>
> As I would like to do 3D surfaces with 3D streamlines and do a movie
> over time (and space) in a sim that has adaptive mesh refinement (so
> it's changing from plot file to plot file), these errors kill the
> pleasure and ease of using VisIt and limit its use (for me) to a data
> prospecting tool.  
>
> One possibility is the use of Ifrit (it currently reads HART AMR data),
> though it requires a bit of coding to read FLASH data (I'm still not
> understanding how to do this, though the fix seems straightforward with
> HART already set up).  The maintainer of Ifrit, Nick Gnedin, thinks
> this would be straightforward to setup however, so if anyone is
> interested+capable...
>
> Thanks to anyone who has read this, and thank you for any feedback!
> Dennis
>   
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