[Paraview] Volume Rendering with opacity mapping and specular highlights

Sun Sep 27 23:39:27 EDT 2015

On Sun, Sep 27, 2015 at 7:36 PM, Mathew Guilfoyle <mrguilfoyle at gmail.com>
wrote:

> Thanks for the reply - the ‘Shade’ setting was the key.  Am I right in
> inferring this property is not exposed for unstructured grids?
>

Right, it is only available for image data one.

>  If I threshold or clip the image data I can no longer turn ‘Shade’ on.
>

Because that creates a unstructured grid I believe.

>
> Does GPU acceleration work on OS X presently?
>

GPURayCast volume mapper which uses vtkImageData works on Mac if you use
OpenGL2 backend.

> Whenever I switch to GPU the image disappears; rendering on the CPU takes
> a long time.  Would this be more likely to work if I compiled the OpenGL2
> version?
>

Yes, please see my comment above.

Thanks,

>
> Cheers
>
> On 25 Sep 2015, at 05:05, Aashish Chaudhary <aashish.chaudhary at kitware.com>
> wrote:
>
>
>
> On Wed, Sep 23, 2015 at 3:34 PM, Mathew Guilfoyle <mrguilfoyle at gmail.com>
> wrote:
>
>> Aashish - thanks for the reply
>>
>> I am using the latest OS X binary download (4.4.0) - is this OpenGL2?
>> When I switch ‘Volume Rendering Mode’ to GPU rendering all images disappear
>> so I presume I’m only able to use CPU rendering.  I am on a 2014 Macbook
>> Pro with Nvidia GT750M.
>>
>
> No it would be OpenGL old version VTK. It would be nice if you can try
> OpenGL2 version although I don't think your problem is related to GL
> version.
>
>>
>> I’m using contrast enhanced volumetric CT imaging.  I want to render
>> blood vessels in red; within the scan they appear in approximately the
>> 100-200 Hounsfield unit range. The full range of scalar data is [-1024,
>> 3071]. On this basis I’ve set up the following colour and opacity mappings:
>>
>> Colour:
>> Value R-G-B
>> -1024 0-0-0
>> 99 0-0-0
>> 100 1-0-0
>> 200 1-0-0
>> 201 0-0-0
>> 3071 0-0-0
>>
>> Opacity:
>> Value Opacity
>> -1024 0
>> 99 0
>> 100 1
>> 200 1
>> 201 0
>> 3071 0
>>
>> None of the voxels appear to be fully opaque in the rendering.  When I
>> increase the specular from 0 to 1 it has no effect at all on the image.
>>
>> Have you enabled the lighting?
> http://www.vtk.org/doc/nightly/html/classvtkVolumeProperty.html(ShadeOn)
> on volume property?
>
> - Aashish
>
>
>> Ideally, I would want to emulate something along the lines of this:
>> http://www.cemuva.com/img/uploads/malformacion-arteriovenosa-cerebral-3d.jpg
>>
>> Again, cheers for the help
>> Mathew
>>
>> On 23 Sep 2015, at 18:24, Aashish Chaudhary <
>> aashish.chaudhary at kitware.com> wrote:
>>
>> Matthew,
>>
>> * Can you send us the exact number you are putting in for the transfer
>> function? Make sure that you have values for the entire range of scalar
>> values?
>>
>> * Are you using OpenGL2 version?
>>
>> - Aashish
>>
>> On Wed, Sep 23, 2015 at 1:18 PM, Mathew Guilfoyle <mrguilfoyle at gmail.com>
>>  wrote:
>>
>>> Thanks for the suggestions.  After looking into it further the type of
>>> visualisation I am after is volume rendering of the data with an opacity
>>> transfer function based on the scalar data values.
>>>
>>> I have set up my volume rendering to have full (i.e =1) opacity through
>>> the range of scalar values I’m interested in, reducing to near transparency
>>> either side of this.  I also want specular highlighting of the opaque
>>> tissues.
>>>
>>> However, despite these settings Paraview does not seem to render any
>>> voxels as fully opaque and there is certainly no specular highlighting.  Is
>>> this a known limitation?
>>>
>>> Many thanks
>>>
>>> On 21 Sep 2015, at 15:10, David E DeMarle <dave.demarle at kitware.com>
>>> wrote:
>>>
>>> Two suggestions:
>>> * try contour filter instead of threshold if contour isn't available,
>>> apply cell to point first.
>>> * try the clip filter with the clip type set to scalar.
>>> hth
>>>
>>> David E DeMarle
>>> Kitware, Inc.
>>> R&D Engineer
>>> 21 Corporate Drive
>>> Clifton Park, NY 12065-8662
>>> Phone: 518-881-4909
>>>
>>> On Mon, Sep 21, 2015 at 9:40 AM, Mathew Guilfoyle <mrguilfoyle at gmail.com
>>> > wrote:
>>>
>>>> I would be grateful for some advice on volume and surface rendering in
>>>> Paraview.
>>>>
>>>> I am trying to generate 3D skull models from CT data.  The reason for
>>>> using Paraview is to take advantage of the detailed fly-through/movie
>>>> capability.  I can generate an acceptable 3D model that I can interact with
>>>> in OsiriX and 3D Slicer, both of which I believe use VTK.  However, in
>>>> Paraview I am struggling to create a 3D model that looks any good.
>>>>
>>>> When I apply a threshold filter and view as a ‘Surface’ the image is a
>>>> lot more ‘blocky’ than in the other two applications.  The image is
>>>> dominated by the artifactual lines due to the original data being acquired
>>>> as axial slices; whereas in OsiriX and 3D Slicer this gets smoothed out and
>>>> the ‘genuine’ surface skull features (sutures etc) stand out.
>>>>
>>>> I realise this is probably question of apply the correct series of
>>>> filters and that the other two apps do this ‘under the hood’.  However, i
>>>> have tried to apply Decimation and Smooth to the extracted surface and am
>>>> not making any headway.
>>>>
>>>> Any pointers would be very welcome
>>>>
>>>> M
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>>>
>>>
>>>
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>>
>>
>> --
>>
>>
>>
>> *| Aashish Chaudhary | Technical Leader         | Kitware Inc.
>>   *
>> *| http://www.kitware.com/company/team/chaudhary.html
>> <http://www.kitware.com/company/team/chaudhary.html>*
>>
>>
>>
>
>
> --
>
>
>
> *| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
> *| http://www.kitware.com/company/team/chaudhary.html
> <http://www.kitware.com/company/team/chaudhary.html>*
>
>
>

-- 

*| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
*| http://www.kitware.com/company/team/chaudhary.html
<http://www.kitware.com/company/team/chaudhary.html>*
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