[yt-dev] Vertex-centred AMR data?

[Erik Schnetter]

Matt

In my notion, there are no cells, only vertices. Or if you want to renaming
things, then there are only cells, no vertices, but the fine a coarse grid
cells do not share faces.

To answer your question specifically: no, it does not matter whether  the
centre of a "cell" is selected. Only the vertices that are selected should
be part of the selection.

-erik

On Wed, Nov 11, 2015 at 8:57 AM, Matthew Turk <matthewturk at gmail.com> wrote:

> Hi Erik,
>
> I have some ideas about this, but it relies heavily on the notion of
> how to regard "vertices" as separate from "cells", or if they should
> not be.  In terms of things like visualization, vertex centered data
> is not a huge leap in functionality, but in terms of data selection we
> need to be careful.  The canonical question is, if you have a region
> selector that includes the *center* of a zone, should all of its
> vertices be selected?  For instance, imagine you have a region
> selector whose corner resides at the center of a (3D) cell.  Does one
> select all eight vertices, since the "cell" is nominally selected, or
> just the one vertex that is included?  If we can answer that, we can
> start the work of implementing.
>
> On Tue, Nov 10, 2015 at 7:11 PM, Nathan Goldbaum <nathan12343 at gmail.com>
> wrote:
> >
> >
> > On Tuesday, November 10, 2015, Erik Schnetter <schnetter at gmail.com>
> wrote:
> >>
> >> I have implemented a front-end for cell-centred Cactus AMR data.
> >>
> >
> > Awesome! We'd love to have this in the public distribution of yt.
> >
> >>
> >>
> >> However, many Cactus simulations use vertex-centred AMR. That is, data
> is
> >> stored at the vertices of a grid (not in the cells), and coarse
> vertices are
> >> at the same locations as fine vertices.
> >>
> >> How do I present such data to yt? Do I need to set grid coordinates
> >> differently, or is there a "vertex centred" flag?
> >>
> >> When vertex-centred data are displayed, then I expect either a "control
> >> volume" around each vertex to have the same value, or to use e.g. linear
> >> interpolation in the cells from the respective boundaries.
> >
> >
> > We don't have good support for vertex-centered AMR data. I think Matt
> would
> > have a better idea of what approaches we might take here.
> >
> >>
> >>
> >> -erik
> >>
> >> --
> >> Erik Schnetter <schnetter at gmail.com>
> >> http://www.perimeterinstitute.ca/personal/eschnetter/
> >
> >
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-- 
Erik Schnetter <schnetter at gmail.com>
http://www.perimeterinstitute.ca/personal/eschnetter/
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