[vtkusers] Different alpha values for scalars

[Sebastien Jourdain]

In fact if you build your own lookuptable, and you put your own color in it,
you are able to put color with alpha. I do not remember exactly the method
names. But then the alpha transition might be smoother than the one you
want.
For your example you can fill your lut with 4 color and set properly the lut
scalar range to behave as closely as you are expecting.

- blue+aplha=0.3
- green+aplha=0.7
- yellow+aplha=0.7
- red+alpha=1

Hope this could help...

On Fri, Mar 19, 2010 at 7:59 AM, Sebastian Gatzka <
sebastian.gatzka at stud.tu-darmstadt.de> wrote:

>  Sounds good.
> Than how can I set three different alpha values for three different scalar
> intervalls?
>
> Am 17.03.2010 21:45, schrieb Sebastien Jourdain:
>
> You can also set alpha in your lookuptable...
>
> On Wed, Mar 17, 2010 at 9:29 AM, Sebastian Gatzka <
> sebastian.gatzka at stud.tu-darmstadt.de> wrote:
>
>>  Sounds good.
>>
>> And how can I mange to unite three different actors on one single cutting
>> plane?
>>
>> Sebastian
>>
>> Am 10.03.2010 16:05, schrieb Rakesh Patil:
>>
>> hi..
>>
>> one option is you can use vtkThreshold, if your threshold ranges are
>> fiixed.. Like in your example, there are three conditions.. So three times,
>> u can use vtkThreshold class and create that many actors..
>>
>> Any other way is there my friends..??
>>
>> Thanks
>>
>> Regards
>> Rakesh Patil
>>
>>
>> ---------- Original message ----------
>> From:Sebastian Gatzka< sebastian.gatzka at stud.tu-darmstadt.de >
>> Date: 10 Mar 10 17:50:06
>> Subject: [vtkusers] Different alpha values for scalars
>> To: vtkusers at vtk.org
>>
>>
>>
>> Hello world.
>>
>> Do you know if it's possible to assign different alpha values to a scalar
>> field representation (for example on a cutting plane)?
>>
>> I want to have scalar to be more transparent if they are below some
>> defined threshold.
>> For example something like this
>>
>>    - scalar < 0.1 : alpha = 0.3
>>    - 0.1 < scalar < 0.5 : alpha = 0.7
>>    - scalar > 0.5 : alpha = 1.0
>>
>> Do you know how I can manage this?
>>
>> Sebastian
>>
>>
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