[vtkusers] 3D modeling .. . prob with thresholding

[dean.inglis at camris.ca]

Florent,

clearly, you are trying to visualize the boundary between
trabecular bone and the surrounding marrow cavities.  It is 
sufficient to set the threshold filter as you already have
and, in fact, you could use a 3D image/volume visualization pipeline to 
(say with vtkVolumeTextureMapper etc.) to also view the results.
You can also use the contour filter as is by setting the iso-contour
value to 101, 100.1, 100.01 etc. or 254.99.  A value of 100 will not
work because there are no scalars in the output of the threshold
filter below 100 to interpolate against, whereas a value of, for
example, 100.1 is between 100 and 255, so it will work.
Either way, you are still visualizing the boundary between 
bone and non-bone.  If you were measuring the area of
the non-bone surface, I would be inclined to extract an iso-value
of 255.

Dean


> 
> From: "Florent.Chandelier at USherbrooke.ca" <Florent.Chandelier at USherbrooke.ca>
> Date: 2004/10/01 Fri AM 09:46:19 GMT-04:00
> To: <dean.inglis at camris.ca>
> Subject: Re: [vtkusers] 3D modeling .. . prob with thresholding
> 
> So I've been adding the Update() to my reader .. of  course that was a 
> big mistake and thx for that.
> now I have a range[0] of 81 and a range[1] fo 255.
> 
> I'll post 6 slices , the .exe and the source of my short prog.
> see : http://florent.chandelier.free.fr/dean.zip
> 
> I've added  the same range thing after my threshold and I get 
> range[0]=100 and range[1]=255 ..... so it seems to be ok but when I use 
> the vtkContourFilter->SetValue to 150 it extracts me some contours, or 
> I've used the inbetween Threshold and it is not supposed to get any 
> result there...
> I guess my way of using the threshold is not proper and I'll check that
> 
> -- 
> Florent Chandelier - florent.chandelier at usherbrooke.ca
> PhD Student at the university of Sherbrooke (QC, Canada)
> Bio mechanical research department - http://www.biomec.gme.usherb.ca/
> 
> Lab Phone : (001) (819)-821-7000
> 
>