[yt-users] Problem with annotate_contour() callback on OffAxisProjectionPlots

[Matthew Turk]

Hi Cameron,

On Tue, Apr 1, 2014 at 4:51 PM, Matthew Turk <matthewturk at gmail.com> wrote:
>
> On Apr 1, 2014 4:42 PM, "Cameron Hummels" <chummels at gmail.com> wrote:
>>
>> Sorry about that--I wasn't totally clear in what I wanted to get out of
>> this.
>>
>> I wanted the contours in test4 to be identical to the contours in test3,
>> since they're both created using annotate_contour() with the same
>> data_source.  Yes, there are contours in test4.png, but they are
>> significantly different from those in test3.  Does this make sense?
>>
>> If you look at the contours for test1 and test2, they match, despite the
>> fact the underlying data being plotted change.
>>
>
> Ah, I understand now.
>
> So, two things. I have used real data (much easier than random) and the
> contours do not match as well as I would like. However, they cannot match
> exactly - you can see this in the random pf by looking at how the off axis
> projections are covered with what look like stencil outlines of cells. These
> won't go away, regardless of what we do with the off six projection, because
> of how the data is created. The on-axis is produced by pixelizing a sparse
> grid of points, which is then fed into a Delaunay triangulation before
> contouring the result. The off axis is already densely packed, which means
> the interpolation process becomes nearest neighbor.
>
> As for the other issue, I believe there is a transposition error combined
> with the fact that linearly interpolating inside a cell produces different
> results during the projecting process. I think you had proposed an
> adjustment to the axis order for OAP objects; did it make it in?

Ah!  I think I found it.  I was doing something wrong in my script; by
setting north_vector and so on, I got identical results for the
different images, *except* that one was clearly weighted when it
shouldn't be.  I tracked this down and have pushed a partial fix here:

https://bitbucket.org/MatthewTurk/yt/commits/1e4ca6c3f7da6a6a7857660690c2207dab934652

Unfortunately, I was unable to finish it because I don't know how the
CallbackWrapper works completely, and it is necessary.  Here we need
to regenerate the FRB from a different data_source, whereas by default
the contours will use the extant FRB.  Nathan, do you know how we
might fix this?  Can we just retain a reference to the window_plot in
the wrapper?

-Matt

>
> Matt
>
>>
>> On Tue, Apr 1, 2014 at 1:32 PM, Matthew Turk <matthewturk at gmail.com>
>> wrote:
>>>
>>> Hi Cameron,
>>>
>>> On Tue, Apr 1, 2014 at 4:11 PM, Cameron Hummels <chummels at gmail.com>
>>> wrote:
>>> > Hey everyone,
>>> >
>>> > I have an unusual problem that I cannot seem to work out.  I'm trying
>>> > to
>>> > generate a set of contours on an OffAxisProjectionPlot using the
>>> > underlying
>>> > data from another OffAxisProjectionPlot (i.e. a different data_source).
>>> > I
>>> > can get this working A-OK when I just use the ProjectionPlot class, but
>>> > when
>>> > I attempt to use the OffAxisProjectionPlot, I encounter problems.
>>> >
>>> > I made a small script demonstrating this problem, as well as the
>>> > success
>>> > when this method is applied to a ProjectionPlot object.  Any
>>> > suggestions?
>>> >
>>> > Note, this is yt 2.x dev.  Here is the script:
>>> >
>>> > http://paste.yt-project.org/show/4459/
>>> >
>>> > Cameron
>>>
>>> My reading of your script is that you want "test4.png" to have
>>> contours on it, right?  I just ran this script on 61e6b84f875c, which
>>> is near tip of 2.x, and I got this image for test4.png:
>>>
>>> http://i.imgur.com/hfycSN9.png
>>>
>>> Is this not what you wanted?
>>>
>>> -Matt
>>>
>>> >
>>> > --
>>> > Cameron Hummels
>>> > Postdoctoral Researcher
>>> > Steward Observatory
>>> > University of Arizona
>>> > http://chummels.org
>>> >
>>> > _______________________________________________
>>> > yt-users mailing list
>>> > yt-users at lists.spacepope.org
>>> > http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>> >
>>> _______________________________________________
>>> yt-users mailing list
>>> yt-users at lists.spacepope.org
>>> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>
>>
>>
>>
>> --
>> Cameron Hummels
>> Postdoctoral Researcher
>> Steward Observatory
>> University of Arizona
>> http://chummels.org
>>
>> _______________________________________________
>> yt-users mailing list
>> yt-users at lists.spacepope.org
>> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>