[yt-users] Cloud in cell deposition

[Matthew Turk]

Hi Cameron,

I believe the following three fields should be available to convert
star particle data to baryon data:

star_density_pyx
star_metallicity_fraction
star_creation_time
star_dynamical_time

All of these take the star particles, selected by "creation_time > 0"
(about which I have conflicted feelings) and deposit either their
masses or their respective quantities into the grid cells.  My
understanding is that where there is no data, the baryon field is set
to zero.  These fields can then be projected, plotted, etc.

This is done via Cloud in Cell interpolation, through a
transliteration (F->C) of the Enzo routine written by Britton Smith.
For a while we had the original Fortran routine directly called, but
fortran/c linkage proved to be a bit of a problem, so this is now a
Cython/C routine.

The longer term solution, which you alluded to above, for depositing
particles will be something like this, where we have a finely-spaced
mesh onto which particles are deposited and then overplotted, rather
than a set of points.  One interesting thing we could try would be
semi-translucent images; one could imagine compositing a deposited
particle field on top of a fixed resolution buffer.

Anyway, just something to think about.  Good luck, and I hope this
helps!  Let us know if it doesn't.

-Matt

On Tue, Jun 1, 2010 at 10:06 PM, Cameron Hummels
<chummels at astro.columbia.edu> wrote:
> Hello everyone:
>
>   I would like to make some images of the stellar (or DM) particles for some
> of my enzo halos.  YT's current abilities for overplotting particle data on
> the grid gas data leaves something to be desired (although a long-term
> solution is being coordinated), so I was looking for an alternative.  Matt
> mentioned that some of you have circumvented this very problem by depositing
> particles into nearby grid cells and then using YT's excellent rendering
> abilities to produce some knockout images.  Does anyone have any suggestions
> on how one might go about generating such an image for, say, star particles?
>  Thanks!
>
> Cameron
>
> --
> Cameron Hummels
> PhD Candidate, Astronomy Department of Columbia University
> Public Outreach Director, Astronomy Department of Columbia University
> NASA IYA New York State Student Ambassador
> http://outreach.astro.columbia.edu
>
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