[vtkusers] creating a solid object from 3D points

[Clare Fitzpatrick]

Hi Tim,
Thanks for your reply.

These points are points from the shaft of a bone. The points are captured as
several 2D slices, each 2D slice taken at a different depth in the bone. The
points at each depth could be rearranged into left-to-right, or ordered
polar coordinate points, without too much trouble. I know it is possible to
do it by creating polygons between adjacent slices, but I was hoping there
might be a more efficent way. I tried using vtkSurfaceReconstructionFilter
which seems to reconstruct the shape of the object, but has altered the
scale and origin ...

Clare



----- Original Message ----- 
From: "Tim Hutton" <tim.hutton at gmail.com>
To: "Clare Fitzpatrick" <clare.fitzpatrick at ucd.ie>
Cc: <vtkusers at vtk.org>
Sent: Monday, September 11, 2006 2:46 PM
Subject: Re: [vtkusers] creating a solid object from 3D points


> Hi Clare,
>
> First of all, are your points completely random or are they captured
> in some direction, such as left-to-right? If so then you will probably
> have more success using this fact to derive a surface. If your points
> are geographical, for example, then a projection into 2D followed by
> vtkDelaunay2D is the best option.
>
> If the points are definitely in a random order then you need some form
> of surface reconstruction. VTK has vtkSurfaceReconstructionFilter but
> it only works if your data is densely sampled all over, and the
> surface is closed.
>
> A better algorithm is found in the following, which is written for VTK
> but covered by the GPL:
> http://www.sq3.org.uk/powercrust/
>
> Tim
>
> On 9/11/06, Clare Fitzpatrick <clare.fitzpatrick at ucd.ie> wrote:
> >
> >
> > Hi,
> >
> > I have a set of x,y,z points which i want to convert to a solid object.
> > I am reading them into vtk using vtkParticleReader:
> >
> > vtkParticleReader reader
> >   reader SetFileName "C:/points3D.txt"
> >   reader SetDataByteOrderToBigEndian
> >
> > vtkPolyDataMapper mapper
> >     mapper SetInputConnection [reader GetOutputPort]
> >
> > vtkActor actor
> >     actor SetMapper mapper
> >     [actor GetProperty] SetPointSize 1
> >
> > ren1 AddActor actor
> >
> >
> > The points in my .txt file are in a random order. Is it possible to
create a
> > solid object (the shape you'd get if you shrink-wrapped something around
all
> > the points) directly from these points, or do i have to arrange them
into a
> > particlar order so that i can use vtkDelaunay2D or vtkCellArray and
> > vtkPolyData to create the surface?
> >
> > Thanks
> >
> > Clare
> >
> >
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>
>
> -- 
> Tim Hutton - http://www.sq3.org.uk
>
> Take the Organic Builder challenge -
> http://www.sq3.org.uk/Evolution/Squirm3/OrganicBuilder/
>