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vtkImageData has an Origin, which is used by the volume mappers to
correctly place the volume in 3D space. It is also used by the contour
filter to produce correct 3D vertices for the triangles. These should
match up. If they do not, then the origin / extent for the data you
are passing into the contour filter does not match the origin /
extent of the data going into the volume mapper (or there is a bug
- but intermixed isosurfaces / volume rendering is something that is
tested nightly....)<br><br>
Lisa<br><br>
<br>
At 01:48 AM 9/6/2005, Peter wrote:<br>
<blockquote type=cite class=cite cite="">vtkExtractVOI gives different
results on vtkContourFilter and vtkVolumeRayCastMapper.<br>
especially the SetVOI <br>
<br>
SetVOI carries arguments in a manner as below:<br>
<br>
SetVOI a b c d e f ( a...f = integer)<br>
<br>
the "a" actually affect the output.<br>
<br>
in vtkContourFilter, when the part was "cut" off, the postion
of the cut-off part will be reserve<br>
<br>
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 ) <br>
<br>
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.... <br>
<br>
thank you for your advice.<br>
<br>
regards<br>
<br>
Yours<br>
Pan<br><br>
<br>
On 9/6/05, <b>Day, Robert</b>
<<a href="mailto:Robert.Day@health.wa.gov.au">
Robert.Day@health.wa.gov.au</a>> wrote: <br>
<dl>
<dd>Its only a guess, based on looking at the picture and no code, and I
don't use volumes much.<br><br>
<dd>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. <br><br>
<dd>It would be easier to guess with some code...<br><br>
<dd>Rob.<br>
<dd>--<br>
<dd>Robert
Day
ph +61 8 9224 3227<br>
<dd>Project Bioengineer fax +61 8 9224 1138<br>
<dd>Royal Perth Hospital
<a href="mailto:robert.day@health.wa.gov.au">
robert.day@health.wa.gov.au</a><br><br>
<dd>> -----Original Message-----<br>
<dd>> From: Peter
[<a href="mailto:meancity@gmail.com" eudora="autourl">
mailto:meancity@gmail.com</a>]<br>
<dd>> Sent: Saturday, 27 August 2005 2:19 PM<br>
<dd>> To: <a href="mailto:vtkusers@vtk.org">vtkusers@vtk.org</a><br>
<dd>> Subject: [vtkusers] volume rendering content does not fit into
the<br>
<dd>> isosurface<br>
<dd>><br>
<dd>><br>
<dd>> Dear All,<br>
<dd>><br>
<dd>> i have a question, i am doing some rending for a 3D object.
<br>
<dd>><br>
<dd>> first i did isosurface rendering for the objects.<br>
<dd>> then i did volume rendering.<br>
<dd>><br>
<dd>> these two rending process in same file, but when i run the
script,<br>
<dd>> the volume rendering content does not fit into the isosurface, i
tried <br>
<dd>> to find the problem, but i still can't figure it out by far. i
suppose<br>
<dd>> the volume rendering content should exactly fit into the
isosurface.<br>
<dd>> but the result showed that there are just some part of<br>
<dd>> overlapping.....<br>
<dd>><br>
<dd>> so can someone out there to help me out on this issue...<br>
<dd>><br>
<dd>> thank you in advance,<br>
<dd>><br>
<dd>> Yours<br>
<dd>> Pan<br>
<dd><snip><br><br>
</dl><br>
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