[yt-dev] Issue #570: Healpix volume rendering produces garbled, artifacted images (yt_analysis/yt)

[Geoffrey So]

Sorry what I meant was the script ran fine without crashing, the image I
got and the script I used is now updated on the bug issue comment section.
 The grid boundary is clearly visible so something seems wrong.

From
G.S.


On Fri, May 17, 2013 at 2:04 PM, Matthew Turk <matthewturk at gmail.com> wrote:

> Can you attach your image to the issue? On the mailing list you also said
> it worked fine I thought.
> On May 17, 2013 5:01 PM, "Geoffrey So" <gsiisg at gmail.com> wrote:
>
>> I can confirm, the images I got looks like the grids were not ordered
>> correctly, patches of zones looks fine inbetween, but zone and zones do not
>> match well at the boundary.
>>
>> From
>> G.S.
>>
>>
>> On Fri, May 17, 2013 at 1:49 PM, Nathan Goldbaum <
>> issues-reply at bitbucket.org> wrote:
>>
>>> New issue 570: Healpix volume rendering produces garbled, artifacted
>>> images
>>>
>>> https://bitbucket.org/yt_analysis/yt/issue/570/healpix-volume-rendering-produces-garbled
>>>
>>> Nathan Goldbaum:
>>>
>>> Using the sample script from the docs:
>>>
>>>
>>> ```
>>> #!python
>>>
>>> from yt.mods import *
>>> import yt.visualization.volume_rendering.camera as camera
>>>
>>> pf = load("IsolatedGalaxy/galaxy0030/galaxy0030")
>>> image = camera.allsky_projection(pf, [0.5,0.5,0.5], 100.0/pf['kpc'], 64,
>>> "Density")
>>> camera.plot_allsky_healpix(image, 64, "allsky.png", "Column Density
>>> [g/cm^2]")
>>> ```
>>>
>>> Produces the following image:
>>>
>>> ![](http://i.imgur.com/5wskzay.png)
>>>
>>> I also tried the manual method described further down in the docs:
>>>
>>>
>>> ```
>>> #!python
>>>
>>> rom yt.mods import *
>>> import yt.visualization.volume_rendering.camera as camera
>>>
>>> Nside = 32
>>> pf = load("IsolatedGalaxy/galaxy0030/galaxy0030")
>>> cam = camera.HEALpixCamera([0.5,0.5,0.5], 0.2, Nside, pf = pf,
>>> log_fields = [False])
>>> bitmap = cam.snapshot()
>>>
>>> import yt.utilities.lib as au
>>> from numpy import pi
>>> phi, theta = np.mgrid[0.0:2*pi:800j, 0:pi:800j]
>>> pixi = au.arr_ang2pix_nest(Nside, theta.ravel(), phi.ravel())
>>> img = np.log10(bitmap[:,0,0][pixi]).reshape((800,800))
>>>
>>> import matplotlib.figure
>>> import matplotlib.backends.backend_agg
>>>
>>> fig = matplotlib.figure.Figure((10, 5))
>>> ax = fig.add_subplot(1,1,1,projection='mollweide')
>>> image = ax.imshow(img, extent=(-pi,pi,-pi/2,pi/2), clip_on=False,
>>> aspect=0.5)
>>> cb = fig.colorbar(image, orientation='horizontal')
>>>
>>>
>>> cb.set_label(r"$\mathrm{Column}\/\mathrm{Density}\/[\mathrm{g}/\mathrm{cm}^2]$")
>>> canvas = matplotlib.backends.backend_agg.FigureCanvasAgg(fig)
>>> canvas.print_figure("allsky.png")
>>>
>>> ```
>>> Note that I had to update this a bit since amr_utils was renamed a while
>>> back.  This produces the following image:
>>>
>>> ![](http://i.imgur.com/Jax1sYB.png)
>>>
>>> While this looks more sensible, it's not clear to me that it is correct.
>>>
>>>
>>> _______________________________________________
>>> yt-dev mailing list
>>> yt-dev at lists.spacepope.org
>>> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>>>
>>
>>
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