[FLASH-USERS] QuickFlash Interpolation Question

[Samuel Friedman]

Dear Nathan,

I played around with the code and looked at fidlr's merge_amr routine.  A 
few things I noticed:

1)  I managed to create very easily a 3D uniform grid from AMR data by 
simply modifying the example routine in map_uniform.  Quite easy.
2)  fidlr's merge_amr routine calls either the IDL function congrid (in 
2D) or rebin (in 3D).  In both cases, they simply use nearest neighbor 
sampling.  So I think the "interpolation" should be really easy to 
implement for QuickFlash.
3)  This is harder, but I tried using map_uniform on a simulation that 
used a uniform grid and QuickFlash gave me an error message (about an 
invalid neighbor code and that mesh information was not available).

The main reason I looked into QuickFlash is that it was pretty much the 
ONLY set of tools outside of IDL avaiable for analysis.  Ultimately, I 
am looking for something without IDL's licensing agreement and fidlr3.0 
does not seem to work properly with GDL.

Sam

On Wed, 17 Feb 2010, Nathan Hearn wrote:

> Hi Sam,
> 
>     Thank you very much for your interest in QuickFlash -- providing
> basic tools for developing your own analysis software is what I
> intended by releasing it!  Indeed, the now-quite-old 1.0.0 release has
> only very simple sampling methods for automated extraction of data
> over large areas.  [Massimo: I do apologize for missing your question
> about slicing in October.  I hope that the current discussion is of
> interest to you.]  QuickFlash's strength continues to be
> high-performance access to raw block data.  However, my desire is to
> have a simple, consistent set of data structures for holding
> interpolated data, and interpolation routines compatible with the
> ghost-cell generation in Paramesh.  (I have not determined how
> Paramesh's inter-block interpolation compares to the method used in
> Fidlr's merge_amr routine that is called by loaddata.)
> 
>     I have been working on some significant functional improvements to
> the QuickFlash library, and I hope to have an interpolation
> infrastructure in the next release.  Unfortunately, development of the
> library is a one-person operation at this point, and is separate from
> the work of my current research position, so I can not make any
> guarantees about how soon it will be available.  (But I can make
> interpolation a priority.)
> 
>     In the meantime, I can certainly provide you with examples of
> filling a uniform mesh with values based on sub-sampling, but they
> would still lead to blocky structure as seen in slices that cover a
> wide range in refinement.  If you wish to develop interpolation
> routines for your own codes using QuickFlash (or help me with
> developing ones within library), I would be more than happy to assist
> you.
> 
> 
> - Nathan
> 
> 
>