[yt-users] multi-field volume projection?

[Matthew Turk]

Stephen,

Sam is right -- as of right now you cannot, for instance, have a
volume rendering blend a "jet" colormap for density with a "hot"
colormap for temperature.  I don't think it makes much sense to expect
the ColorTransferFunction to return a "multi-field" image unless the
multiple fields were combined into a single field.  You can use
multiple fields in the generation of a single image, by weighting and
so on -- similar to how the PlanckTransferFunction works.  You can
also project multiple fields simultaneously in a volume rendering with
the ProjectionTransferFunction.  This will give you an image whose
first channel is one field, second is another, for instance.  Then you
can either blend these as two independent channels together, with a
function such as or similar to multi_image_composite, or create a 2D
colormap and use that.

-Matt

On Mon, Oct 31, 2011 at 12:33 AM, Sam Skillman <samskillman at gmail.com> wrote:
> Hi Stephen,
> It is not currently possible to do this with the existing framework.  That
> said, I think you might be able to do a decent job just blending two
> separate renders together.  The difficulty in doing two fields on the
> fly (in addition to building the framework to do so) would be finding a
> balance  between the two separate alpha channels so that one didn't dominate
> the other.
> Anyways, while it isn't possible now, you may want to add it as a feature
> request for a future project.
> Best,
> Sam
>
> On Sun, Oct 30, 2011 at 10:20 PM, Stephen Skory <s at skory.us> wrote:
>>
>> Hi all,
>>
>> I may be asking something that is obvious to others, but it's not to
>> me. It is it possible to have more than one data field displayed in a
>> single volume projection image? Say, each with a different color map?
>> If so, how? Thanks!
>>
>> --
>> Stephen Skory
>> s at skory.us
>> http://stephenskory.com/
>> 510.621.3687 (google voice)
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