[Paraview] Volume Rendering with opacity mapping and specular highlights

Sun Sep 27 19:36:26 EDT 2015

Thanks for the reply - the ‘Shade’ setting was the key.  Am I right in inferring this property is not exposed for unstructured grids?  If I threshold or clip the image data I can no longer turn ‘Shade’ on.

Does GPU acceleration work on OS X presently?  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?

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 <mailto: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 <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 <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 <mailto: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 <mailto: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 <mailto: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 <tel:518-881-4909>
>>> On Mon, Sep 21, 2015 at 9:40 AM, Mathew Guilfoyle <mrguilfoyle at gmail.com <mailto: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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>> -- 
>> | 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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