[Paraview] Visualize a curve field

[David E DeMarle]

Put the request on the bug tracker please.

It comes up often on the mailing list. It's not been fixed before
because we don't want to slow down the common case of rendering convex
polygons to find and fix the uncommon case of rendering concave ones.
My recollection from discussions on the mailing list is that a general
solution (apply filter x,y,z to tesselate) turns out to be harder than
it appears at first.

David E DeMarle
Kitware, Inc.
R&D Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909


On Wed, Aug 1, 2012 at 11:36 AM, Samuel Key <samuelkey at bresnan.net> wrote:
> Greetings Dave,
>
> This is a request for a minor(?) alter in a VTK rendering algorithm.
>
> Polyhedral finite elements are reaching a level of numerical maturity where
> their use is likely to become widespread  -- and correspondingly an
> increased desire to display them in ParaView. For convex polygonal faces of
> a polyhedron, the VTK algorithms work fine, and omitting the interior
> triangle edges was a nice rendering improvement.
>
> However, the discrete numerical algorithms that have emerged surprisingly
> work for polyhedrons that have the "star property." Long story told short,
> the attached ParaView figure in the right hand panel contains a polyhedral
> finite element that has a non-planar, concave polygonal face. Numerically,
> this polyhedral configuration works very well.
>
> Would it be possible for rendering purposes, to create the polygon's
> triangular sub-facets by starting with the polygon's vertex closest to the
> average coordinate of the polygon's vertex nodal points? Maybe this
> particular polygon vertex becomes a "common" vertex for all of the
> sub-triangles?
>
> Samuel W. Key
> FMA Development, LLC
>
>
>
> On 8/1/2012 4:27 AM, David E DeMarle wrote:
>>
>> Each polygon in your data file has only two points. They need 3 or
>> more coplanar points and must not be concave for VTK to work with
>> them. Also, the last polygon references point id 3, which doesn't
>> exist.
>>
>> David E DeMarle
>> Kitware, Inc.
>> R&D Engineer
>> 21 Corporate Drive
>> Clifton Park, NY 12065-8662
>> Phone: 518-881-4909
>>
>>
>> On Tue, Jul 31, 2012 at 6:14 PM, Sanket Jain <jainsanket1 at gmail.com>
>> wrote:
>>>
>>> Hello Members,
>>>
>>> I created a sample vtk file to visualize a curve in Paraview. It reads in
>>> without any errors but nothing comes on the viewer. Can someone point in
>>> the
>>> right direction to fix this?
>>>
>>> Sanket
>>>
>>> _______________________________________________
>>> Powered by www.kitware.com
>>>
>>> Visit other Kitware open-source projects at
>>> http://www.kitware.com/opensource/opensource.html
>>>
>>> Please keep messages on-topic and check the ParaView Wiki at:
>>> http://paraview.org/Wiki/ParaView
>>>
>>> Follow this link to subscribe/unsubscribe:
>>> http://www.paraview.org/mailman/listinfo/paraview
>>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the ParaView Wiki at:
>> http://paraview.org/Wiki/ParaView
>>
>> Follow this link to subscribe/unsubscribe:
>> http://www.paraview.org/mailman/listinfo/paraview
>>
>