[yt-dev] Gadget status

Wed Jul 16 04:41:00 PDT 2014

On Tue, Jul 15, 2014 at 6:18 PM, Sam Skillman <samskillman at gmail.com> wrote:
> Hi all,
>
> VR for particle-based simulations doesn't currently work, but I'm not
> entirely sure why. At some point I thought we could render the deposited
> fields but I haven't checked/tried in a while.

My recollection is that it's unrelated to the camera interface, but is
instead something with the kD-tree trying to split octs
(unsuccessfully), which affects RAMSES and ART data as well.

>
> As Cameron mentioned, we're moving towards a new (and hopefully better!)
> camera system (albeit slowly due to me being away from this for a while),
> but the timescale on that is not set in stone. I expect the new camera
> interface will first be implemented for grid-based datasets. Then we can
> hopefully have others that are more familiar with rendering options for
> particle datasets help implement new methods that are beyond just particle
> splatting.
>
> Cheers,
> Sam
>
>
>
>
> On Tue, Jul 15, 2014 at 3:16 PM, Chris Malone <chris.m.malone at gmail.com>
> wrote:
>>
>> Ok, thanks guys.  I figured that was the case with VR, but wanted to
>> double check.
>>
>> The field docs will be a great boon; as it is, things are quite confusing.
>>
>> Nice talk Nathan!
>>
>> Chris
>>
>>
>> On Tue, Jul 15, 2014 at 4:06 PM, Cameron Hummels <chummels at gmail.com>
>> wrote:
>>>
>>> I don't think VR is working for particle-based datasets as of yet.  The
>>> volume rendering interface is being redesigned right now, but its release
>>> has been postponed until yt 3.1 unfortunately.  When it is released it will
>>> handle all particle-based datasets as well as grid-based datasets.
>>>
>>> I know Matt is working on the field docs right now, so they should be
>>> ready somewhat soon.
>>>
>>>
>>> On Tue, Jul 15, 2014 at 3:00 PM, Nathan Goldbaum <nathan12343 at gmail.com>
>>> wrote:
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Jul 15, 2014 at 2:56 PM, Chris Malone <chris.m.malone at gmail.com>
>>>> wrote:
>>>>>
>>>>> Thanks for the feedback, Nathan.
>>>>>
>>>>> In slices, I was plotting 'all_density', which is a 'deposit' field.
>>>>> I'll try looking at 'Gas_smoothed_density' ...
>>>>>
>>>>
>>>> ('deposit', 'all_density') uses nearest neighbor deposition.  There's
>>>> also ('deposit', 'all_cic') which does cloud-in-cell.
>>>>
>>>> ('deposit', 'Gas_smoothed_density') is aliased to ('gas', 'density') or
>>>> just 'density'.  This way we can access gas fields in an SPH dataset just
>>>> like with a grid dataset.
>>>>
>>>>>
>>>>> I'll see about getting permission to pass along the dataset.  For the
>>>>> time being, do you know of any notebook or cookbook recipe that shows how to
>>>>> do this for particle data?  I couldn't seem to find anything.
>>>>
>>>>
>>>> Yes, there's an example in the docs using tipsy data:
>>>> http://yt-project.org/docs/dev-3.0/examining/loading_data.html#tipsy-data
>>>>
>>>> I also went into a bit of depth about working with SPH data in my scipy
>>>> talk: www.youtube.com/watch?v=sNkN7nyj4nE
>>>>
>>>> I don't think there's an example of volume rendering SPH data floating
>>>> around, thus my uncertainty about it working or not.
>>>>
>>>>>
>>>>>
>>>>>
>>>>> Chris
>>>>>
>>>>>
>>>>> On Tue, Jul 15, 2014 at 3:43 PM, Nathan Goldbaum
>>>>> <nathan12343 at gmail.com> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Tue, Jul 15, 2014 at 2:35 PM, Chris Malone
>>>>>> <chris.m.malone at gmail.com> wrote:
>>>>>>>
>>>>>>> Hi all,
>>>>>>>
>>>>>>> Caveat: I'm not that familiar with particle-based datasets/codes.
>>>>>>>
>>>>>>> I'm unsuccessfully trying to help a summer student do some
>>>>>>> visualization of someone else's Gadget binary data dump.  What is the status
>>>>>>> of volume rendering SPH/Gadget data in 3.0?
>>>>>>
>>>>>>
>>>>>> Not sure about volume rendering.  I believe it should work for
>>>>>> particle/octree data but haven't tried it recently.
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> When I've tried what I know works for grid-based data, the returned
>>>>>>> image is simply empty.  Projections look okay (for some variables), and
>>>>>>> Slices look worse as there are blank splotches, likely due to emptiness in
>>>>>>> the tree.
>>>>>>>
>>>>>>
>>>>>> What field are you slicing?  There shouldn't be empty spots for SPH
>>>>>> smoothed fields.
>>>>>>
>>>>>>>
>>>>>>> Also, is there a list somewhere that describes/defines what the
>>>>>>> various fluid types mean (e.g. 'all', 'gas', 'deposit', etc)?  If not, it
>>>>>>> might be nice to have somewhere in the docs.
>>>>>>>
>>>>>>
>>>>>> There are several open issues about this. We won't be releasing yt-3.0
>>>>>> until these docs are written.
>>>>>>
>>>>>> 'all' is the union that contains all particle data.
>>>>>>
>>>>>> 'gas' (lowercase g) corresponds to SPH smoothed quantities for Gadget.
>>>>>> In binary datasets, the Gas particle type corresponds to the gas particles.
>>>>>>
>>>>>> 'deposit' corresponds to fields that are deposited onto the octree
>>>>>> mesh using a particle type. The SPH smoothed fields are actually defined
>>>>>> here, 'gas' is just an alias to the smoothed deposition fields.
>>>>>>
>>>>>> If you have more specific questions (even better if you have an
>>>>>> example script and a dataset) one of us should be able to help you out more.
>>>>>>
>>>>>> -Nathan
>>>>>>
>>>>>>>
>>>>>>> Chris
>>>>>>>
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>>>>>>>
>>>>>>
>>>>>>
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>>>>>
>>>>>
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>>>
>>>
>>>
>>> --
>>> Cameron Hummels
>>> Postdoctoral Researcher
>>> Steward Observatory
>>> University of Arizona
>>> http://chummels.org
>>>
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