On Tue, Jul 15, 2014 at 2:56 PM, Chris Malone <chris.m.malone@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@gmail.com> wrote:

On Tue, Jul 15, 2014 at 2:35 PM, Chris Malone <chris.m.malone@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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