[vtkusers] Make Smooth Isosurfaces

[Bill Lorensen]

Perhaps your scalar values are not associated with the proper points?
Have you looked at the original unstructured grid with paraview?

On Thu, Oct 29, 2009 at 10:21 PM, Sanket Jain <jainsanket1 at gmail.com> wrote:
> Yes, I tried for number of isovalues. But all of them have similar
> characteristics. Is it anything to do with the vtk file being in
> unstructured grid rather than polygonal data? For the mesh, I imported from
> COMSOL, I cannot use polygonal data.
>
> Sanket Jain
> On Thu, Oct 29, 2009 at 6:33 PM, Bill Lorensen <bill.lorensen at gmail.com>
> wrote:
>>
>> It does look strange. Have you tried changing the isosurface value?
>>
>> On Thu, Oct 29, 2009 at 5:44 PM, Sanket Jain <jainsanket1 at gmail.com>
>> wrote:
>> > I have attached a snapshot of my viewer. The isosurface is predicting
>> > the
>> > volume activated during monopolar stimulation. So, theoretically you
>> > will
>> > expect a sphere at a particular iso value.
>> >
>> > I tried using vtkPolyDataNormals. The figure attached is the output
>> > after
>> > including this filter. But I still think this is not smooth.
>> >
>> > I verified by opening my vtk file in Paraview (with, Compute Normal ON).
>> > Even then i get the same kind of response. So, do you think this is the
>> > best
>> > i can get? Or there might be some problem in the vtk file which is
>> > exported
>> > from COMSOL (I verified it multiple times).
>> >
>> > Thank you,
>> >
>> > Sanket
>> >
>> > On Thu, Oct 29, 2009 at 4:01 PM, Bill Lorensen <bill.lorensen at gmail.com>
>> > wrote:
>> >>
>> >> Sorry, reading your e-mail in more detail. Are you generating the
>> >> isosurfaces in vtk using vtkContourFIiter or some equivalent. If so,
>> >> you should run the output through vtkPolyDataNormals.
>> >>
>> >> On Thu, Oct 29, 2009 at 4:59 PM, Bill Lorensen
>> >> <bill.lorensen at gmail.com>
>> >> wrote:
>> >> > What do you mean by rough? Perhaps the faces are flat shaded? How are
>> >> > you displaying the model in vtk?
>> >> >
>> >> > Are your isosurfaces composed of only triangles? If so, did you
>> >> > provide surface normals at each point?
>> >> >
>> >> > On Thu, Oct 29, 2009 at 4:30 PM, Sanket Jain <jainsanket1 at gmail.com>
>> >> > wrote:
>> >> >> Hello Experts,
>> >> >>
>> >> >> I have just started to use VTK to fulfill my visualization needs. I
>> >> >> am
>> >> >> trying out few fundamental steps which would be crucial for my
>> >> >> future
>> >> >> development.
>> >> >>
>> >> >> I exported an  Finite Element Model (FEM) from COMSOL and wrote it
>> >> >> as
>> >> >> vtk
>> >> >> unstructured grid in matlab (points, connections and data). I am
>> >> >> just
>> >> >> trying
>> >> >> to read my vtk file and trying to visualize the isosurfaces at some
>> >> >> value.
>> >> >>
>> >> >> The problem is the isosurfaces are very rough even when I increased
>> >> >> the
>> >> >> mesh
>> >> >> density in my COMSOL model. I tried to perform the same task in
>> >> >> paraview and
>> >> >> even there i saw the same problem.
>> >> >>
>> >> >> Do you think that increasing the mesh density should solve it? I
>> >> >> cannot
>> >> >> increase the mesh density because of computational issues. Any ideas
>> >> >> on
>> >> >> this
>> >> >> problem will be appreciated.
>> >> >>
>> >> >> Thank you,
>> >> >>
>> >> >> Sanket Jain
>> >> >>
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>> >> >>
>> >> >
>> >
>> >
>> >
>> > --
>> > Sanket Jain
>> >
>
>
>
> --
> Sanket Jain
>