[vtkusers] Sphere with scalar values

[David Doria]

On Sat, Jan 16, 2010 at 12:04 PM, KS Jothybasu <jothybasu at gmail.com> wrote:
> Hi David,
>
> What you said is true, finding  the points  inside the sphere and setting
> its scalar value.
>
> But, my problem is that, I need to move the sphere to multiple positions and
> do some calculations with the sphere scalar values and the scalar values of
> the vtkimagedata. If I can set the scalars to the sphere directly,I don't
> need to recompute those scalars for each and every position of sphere.
>
> Did you get it? I can give you some more explanation if you wish.
>
> Shall I create the sphere from scratch, as a vtkVolume/vtkPolydata, if so ,
> any examples...
>
>
> Thanks
>
> Jothy
>
> On Sat, Jan 16, 2010 at 4:52 PM, David Doria <daviddoria+vtk at gmail.com>
> wrote:
>>
>> On Sat, Jan 16, 2010 at 11:49 AM, KS Jothybasu <jothybasu at gmail.com>
>> wrote:
>> > vtkPSphereSource means "sphere source that supports pieces " as the vtk
>> > doc
>> > says.
>> >
>> > I don't understand what supporting pieces means.
>> >
>> > Regarding my sphere object.
>> >
>> > I need to create a sphere object, let's say 5 cm radius. Indise that I
>> > want
>> > to set scalar values as we set for vtkImageData with
>> > SetScalarComponentFromFloat(x,y,z,0,HU).
>> >
>> > Thanks
>> >
>> > Jothy
>> >
>> >
>> >
>> > On Sat, Jan 16, 2010 at 4:37 PM, David Doria <daviddoria+vtk at gmail.com>
>> > wrote:
>> >>
>> >> On Sat, Jan 16, 2010 at 10:30 AM, KS Jothybasu <jothybasu at gmail.com>
>> >> wrote:
>> >> > Hi,
>> >> >
>> >> > I am trying to create a sphere object comprising of voxels and
>> >> > setting
>> >> > the
>> >> > scalar values. But I am yet a find a proper method to do this.
>> >> >
>> >> > Could any of you please give me a hint?
>> >> >
>> >> > Should I create sphere object with polydata?
>> >> >
>> >> > What's the difference between vtkSphereSource and vtkPSphereSource
>> >> >
>> >> > Thanks
>> >> >
>> >> > Jothy
>> >> >
>> >>
>> >> If I understand correctly, vtkP* means it is a parallel version of the
>> >> vtk* filter. I don't think it has any relevance to your question.
>> >>
>> >> I guess I don't follow what you mean by "a sphere object comprising of
>> >> voxels". Can you elaborate or give an example?
>> >>
>> >> Thanks,
>> >>
>> >> David
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>>
>> Please keep the discussion on the mailing list.
>>
>> I agree that "supporting pieces" is not very clear. What I believe it
>> means is that the memory that comprises the object is split into
>> "pieces" which reside on multiple computers (hence, the parallel
>> version of the object).
>>
>> Why don't you just create an ImageData and for each point in the
>> ImageData test if it is inside your sphere. If it is, then set it's
>> scalar value.
>>
>> Will that work?
>>
>> Thanks,
>>
>> David

Again, please keep the discussion on the mailing list.

Can't you just apply the transformation that you would have applied to
the sphere to the ImageData instead to position the scalars in your
scene?

Thanks,

David