[vtkusers] vtkImageReader - SetDataSpacing - What is it doing?

[Sean Larkin]

From: Sean Larkin [mailto:sean.larkin at lickenbrocktech.com] 
Sent: Friday, October 14, 2011 4:14 PM
To: 'Bill Lorensen'
Subject: RE: [vtkusers] vtkImageReader - SetDataSpacing - What is it doing?

 

That's what I'm thinking as well.  I understand that if the pixel spacing is
larger the opacity may change, which would change the rendered image.  But ,
if I adjust the opacity function I can never get as good an image as with
larger pixel spacing.  Maybe with smaller pixel spacing there are fewer rays
cast to produce the image?

 

From: Bill Lorensen [mailto:bill.lorensen at gmail.com] 
Sent: Friday, October 14, 2011 3:42 PM
To: Sean Larkin
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] vtkImageReader - SetDataSpacing - What is it doing?

 

I suspect that the volume mapper has some settings that are specified in
physical units.


On Friday, October 14, 2011, Sean Larkin <sean.larkin at lickenbrocktech.com>
wrote:
> Hello,
>
> I'm using vtkImageReader to loading a 3D volume and render it with
vtkVolumeMapper.  I want to be able to adjust the voxel aspect ratio, so I
decided to use the SetDataSpacing() method of vtkImageReader.  Is this the
best way to do this?  I ask this because I can get very different looking
rendered images when I use the same aspect ratio, with different values.
For example, when I set the spacing to [.043,.043,1] I get poor resolution
compared to when I use [1,1,23.3] (these are the same ratios).    Does
anyone know why this is happening?
>
>  
>
> Thanks,
>
> Sean Larkin 

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