[yt-users] Ray casting in simple volume rendering

[Nicholas M. Earl]

Hey Matt,

Yeah, it's 3d data.

Nick

On Mar 31, 2010, at 12:58 PM, Matthew Turk wrote:

> Hi Nick,
>
> Are you using 3D data?
>
> -Matt
>
> On Wed, Mar 31, 2010 at 9:55 AM, Nicholas Earl <earlnich at msu.edu>  
> wrote:
>> This all sounds exciting, and I'm definitely making headway in  
>> terms of
>> progress on the screen, but I keep getting hung up at a ValueError:  
>> shape
>> mismatch: objects cannot be broadcast to a single shape after this  
>> line:
>>
>>     vcd = grid.get_vertex_centered_data(field).astype('float64')
>>   File "/Users/earln/yt-i386/src/yt-trunk-svn/yt/lagos/ 
>> BaseGridType.py",
>> line 445, in get_vertex_centered_data
>>     na.add(new_field, cf[1: ,1: ,1: ], new_field)
>>
>> Not quite sure wherein this would lie. Any possible ideas?
>>
>> Thanks!
>> Nick
>>
>> On Tue, Mar 30, 2010 at 2:20 PM, Matthew Turk  
>> <matthewturk at gmail.com> wrote:
>>>
>>> Hi Nicholas,
>>>
>>> Yup, the cookbook applies to 1.6, but we've changed things a bit in
>>> the trunk so as to enable parallel volume rendering -- and to make
>>> some things nicer.  For instance, you can now sample colormaps,
>>> automatically add layers, etc etc.  We're also just about ready to
>>> roll out multivariate volume rendering, including planck functions  
>>> and
>>> scattering.
>>>
>>> Anyway, I'm sorry that it's not working right now for you!  To use  
>>> the
>>> script, we just need to get rid of direct_ray_cast, which we can
>>> replace with:
>>>
>>> vp = pf.h.volume_rendering(L, W, c, Nvec, tf)
>>> vp.ray_cast()
>>>
>>> At this point, we can get the image as vp.image:
>>>
>>> to_plot = na.clip(vp.image, vp.image.min(), 0.8 * vp.image.max())
>>> to_plot = (to_plot - to_plot.min()) / (to_plot.max() -  
>>> to_plot.min())
>>>
>>> (we still have to normalize, unfortunately -- we're working on that
>>> for the future.)
>>>
>>> And we now also provide a saving function:
>>>
>>> vr.plot_rgb(to_plot, "%s" % pf)
>>>
>>> I've uploaded a new version of the cookbook recipe here:
>>>
>>> http://paste.enzotools.org/show/404/
>>>
>>> which you can download with "yt_lodgeit.py --download=404".  One  
>>> thing
>>> you might consider is that sometimes it's easier to just
>>> "add_layers(N)" on the transfer function, optionally supplying the
>>> name of a colormap (defaults to gist_stern) so that yt will add  
>>> onion
>>> layers to your image at even intervals.  I've uploaded an example of
>>> that here:
>>>
>>> http://paste.enzotools.org/show/405/
>>>
>>> Anyway, sorry for the trouble, but I hope that the annoyance is  
>>> worth
>>> the new advantages!
>>>
>>> -Matt
>>>
>>> On Tue, Mar 30, 2010 at 11:07 AM, Nicholas M. Earl  
>>> <earlnich at msu.edu>
>>> wrote:
>>>> Hey again YT community,
>>>>
>>>> I was hoping to get some heading on using the simple volume rending
>>>> script
>>>> that is written up in the YT cookbook, but it seems that
>>>> direct_ray_casting
>>>> isn't a part of yt extensions anymore? Is there something to  
>>>> substitute
>>>> this? I see that in the software sample script, there is a  
>>>> referencing
>>>> of
>>>> VolumeRendering, can I use this?
>>>>
>>>> Thanks for your time and effort!
>>>> Nicholas Earl
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