[vtkusers] volume rendering content does not fit into the isosurface

[Peter]

vtkExtractVOI gives different results on vtkContourFilter and 
vtkVolumeRayCastMapper.
especially the SetVOI 
 SetVOI carries arguments in a manner as below:
 SetVOI a b c d e f ( a...f = integer)
 the "a" actually affect the output.
 in vtkContourFilter, when the part was "cut" off, the postion of the 
cut-off part will be reserve
 however in vtkVolumeRayCastMapper, it does not reserve the space of the 
cut-off part, and pushes the whole object to left (simply because the left 
cut-off part is no more there ) 
 so it make the volumn rendering content can not "register" with iso-surface 
rendering. i know the cause of the problem, but i haven't find the solution 
yet.... maybe there are some other implementation on this.... 
 thank you for your advice.
 regards
 Yours
Pan


On 9/6/05, Day, Robert <Robert.Day at health.wa.gov.au> wrote: 
> 
> Its only a guess, based on looking at the picture and no code, and I don't 
> use volumes much.
> 
> I'd say the origin for the volume data set is not the same as the surface. 
> As I recall, volumes have the origin at one corner, whereas the CT may well 
> have the origin at the isocentre of the scanner. So the surface polydata 
> will inherit this origin, but the volume may well have its origin at the 
> corner.
> 
> It would be easier to guess with some code...
> 
> Rob.
> --
> Robert Day ph +61 8 9224 3227
> Project Bioengineer fax +61 8 9224 1138
> Royal Perth Hospital robert.day at health.wa.gov.au
> 
> > -----Original Message-----
> > From: Peter [mailto:meancity at gmail.com]
> > Sent: Saturday, 27 August 2005 2:19 PM
> > To: vtkusers at vtk.org
> > Subject: [vtkusers] volume rendering content does not fit into the
> > isosurface
> >
> >
> > Dear All,
> >
> > i have a question, i am doing some rending for a 3D object.
> >
> > first i did isosurface rendering for the objects.
> > then i did volume rendering.
> >
> > these two rending process in same file, but when i run the script,
> > the volume rendering content does not fit into the isosurface, i tried
> > to find the problem, but i still can't figure it out by far. i suppose
> > the volume rendering content should exactly fit into the isosurface.
> > but the result showed that there are just some part of
> > overlapping.....
> >
> > so can someone out there to help me out on this issue...
> >
> > thank you in advance,
> >
> > Yours
> > Pan
> <snip>
>
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