[yt-users] Volume renderings that are too dark

Cameron Hummels chummels at gmail.com
Tue Apr 22 17:10:50 PDT 2014


Thanks for the code and explanation, Sam.  I'll try this out.


On Tue, Apr 22, 2014 at 3:41 PM, Sam Skillman <samskillman at gmail.com> wrote:

> Hi Cameron, I always just save them first then enhance them later, since
> that's an irreversible step. There is a hub project but I can't find it at
> the moment. Here's the script that the hub project links to.
>
>
> https://bitbucket.org/samskillman/rendering_enhancement/src/a0dc61e45e923e10d84202c4f17cb66fa989a820/enhance.py?at=default
>
> The main reason clip_ratio isn't doing anything there is that the alpha
> channel in the example notebook (since grey_opacity=True) is 1.0. This ends
> up messing with the logic in clip_ratio, and tends to either muck up the
> image or do nothing.
>
> Cheers,
> Sam
>
>
> On Tue, Apr 22, 2014 at 3:22 PM, Cameron Hummels <chummels at gmail.com>wrote:
>
>> Hello,
>>
>> I'm having some issues with volume renderings being too dark in yt 2.x.
>>  I know that in the past, people have recommended using the "clip_ratio"
>> argument in the various Camera methods in order to enhance the output image
>> by clipping the values at some multiple of the standard deviation of the
>> array.  Unfortunately, I'm having trouble getting it to actually do
>> anything recently.
>>
>> I slightly modified the notebook from the yt docs cookbook entry on the
>> TransferFunctionHelper to demonstrate this issue.  If you scroll down to
>> the bottom of the notebook to the bold text, you'll see what I mean.
>>  Perhaps I'm misusing this infrastructure, but I figured I'd check with
>> people here to set me straight.
>>
>> http://nbviewer.ipython.org/gist/anonymous/11196301
>>
>> Oh, and note that this is simply an example--I don't think *this* VR is
>> too dark in the notebook, but many of the ones that I generate are too
>> dark, and I'd like to brighten them.
>>
>> Thanks for the help!
>>
>> Cameron
>>
>> --
>> Cameron Hummels
>> Postdoctoral Researcher
>> Steward Observatory
>> University of Arizona
>> http://chummels.org
>>
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>
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-- 
Cameron Hummels
Postdoctoral Researcher
Steward Observatory
University of Arizona
http://chummels.org
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