[vtkusers] "Filling" parts of a volume that are "inside" a set of polyhedra

[Elvis Stansvik]

2017-07-24 5:25 GMT+02:00 Dean Inglis <inglis.dl at gmail.com>:
> good to know David, thanks!!!

Many thanks to both of you. I had not found vtkPolyDataToImageStencil
yet, but was looking more towards the concept of implicit functions.
But this sounds like a much better approach, so I think I was right in
reaching out :)

Elvis

>
> - Dean
>
> On Sun, Jul 23, 2017 at 11:21 PM, David Gobbi <david.gobbi at gmail.com> wrote:
>>
>> Hi Elvis,
>>
>> I'd recommend generating a stencil with vtkPolyDataToImageStencil, then
>> iterating over over all the voxels inside the stencil with
>> vtkImagePointDataIterator:
>>
>> http://www.vtk.org/doc/nightly/html/classvtkPolyDataToImageStencil.html
>> http://www.vtk.org/doc/nightly/html/classvtkImagePointDataIterator.html
>>
>> The iterator can efficiently give you the pointId for every voxel enclosed
>> by the polyhedral surface (works for concave as well as convex surfaces).
>> Once you have the pointId, you can set that voxel to whatever you want.
>> There's a brief and vaguely relevant description on gitlab:
>> https://gitlab.kitware.com/vtk/vtk/merge_requests/1118
>>
>>  - David
>>
>>
>> On Sun, Jul 23, 2017 at 6:45 PM, Elvis Stansvik
>> <elvis.stansvik at orexplore.com> wrote:
>>>
>>> Hi all,
>>>
>>> I have a set of points describing multiple convex polyhedra. The
>>> polyhedra are for the most part disjoint in space, but they may
>>> intersect slightly in some places.
>>>
>>> I need to create an empty voxel volume (all scalars 0), and then
>>> "fill" the voxels that are inside one (or several) of the polyhedrons
>>> with some Perlin noise. I also have access to normals for the faces
>>> constituting the polyhedra, if necessary.
>>>
>>> Finally, I also have a single separate polyhedron (non-convex this
>>> time), and as a finishing step, I'd like to fill the voxels that are
>>> inside this polyhedron with a constant scalar value.
>>>
>>> Can VTK help me here?
>>>
>>> As this is new territory for me as far as VTK goes, any
>>> pointers/advice on how to go about it would be much appreciated.
>>>
>>> Cheers,
>>> Elvis
>>
>>
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>