[yt-dev] Projection issues

[Matthew Turk]

On Wed, Mar 14, 2012 at 5:48 PM, david collins <antpuncher at gmail.com> wrote:
> Hi again--
>
> I have another odd issue, again stemming from with this vintage
> dataset.  It's a 512^3 root with 4 levels, and a refinement by 4.
>
> When the parallel analysis gave me problems yesterday, I tried
> re-griding the data by restarting and forcing parallel root grid io on
> (including a removal of the rebuild hierarchy call to ensure the grids
> stay the same, and returning before any hydro is done.)  The odd bit
> is now projections look different.  Attached are two images,
> sphere_serial is through the old serial  root grid run,
> sphere_parallel is through the output with parallel root grid io.
> Centered on the max, 0.02 in radius, Density projection.  Projections
> were made using
> proj = pf.h.proj(ax,field,center=center,source=sphere)  You can see
> that less structure seems to be captured in the parallel dataset.
>
> I've done two checks to make sure that it's not a glitch in the
> re-griding.  First is the actual data-- the grids are in a different
> order from parallel to serial, but once that's taken into account all
> the data in subgrids is identical (at least in density, the field in
> question).  Additionally the new tiles match the corresponding
> positions in the old tile.  So the data itself is fine.
>
> The other test I did was to regrid, but leaving serial root grid io
> on-- new serial set is identical (except again for grid order) to the
> old, and the projections match.
>
> Differences also show up in profiles.
>
> Again, not a major problem, but it's pretty counter-intuitive, so I
> was wondering if anyone had run into this.

I haven't run into this, but my initial guess is that the hierarchy is
no longer completely accurate.  This can be tested by doing:

nc = sum(g.child_mask.sum() for g in pf.h.grids)
print nc

This number should be the same for both, and if it isn't, there's a
problem with child/parent relationship.

-Matt

>
> d.
>
>
> --
> Sent from my computer.
>
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