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[IV3D-USERS] Re: Loading Label volumes


Chronological Thread 
  • From: James J Cook <james.j.cook@duke.edu>
  • To: tom fogal <tfogal@sci.utah.edu>
  • Cc: iv3d-users@sci.utah.edu
  • Subject: [IV3D-USERS] Re: Loading Label volumes
  • Date: Fri, 13 May 2011 16:49:39 -0400

Sorry i forgot version, i'm using v2.0 download from website, 2 days old.

My data started as 8 bit values from 0 to 37 with 0 as background.
I tried a few things, including converting to 16bit and scaling my values to fit between 0-32768.
This problem occured for an 8 or 16-bit volume. Scaled and not scaled.
Can i turn off that trilinear interpolation for rendering? That might be just what i want to do.        

If i build from svn will this option be available?

James Cook
CIVM, Duke University
Office: (919) 684-7672
Cell: (919) 768-3293


tom fogal <tfogal@sci.utah.edu>

05/13/11 04:25 PM

To
James J Cook <james.j.cook@duke.edu>
cc
iv3d-users@sci.utah.edu
Subject
Re: [IV3D-USERS] Loading Label volumes





Hi,

James J Cook <james.j.cook@duke.edu> writes:
>   I am loading a 3d analyze format image volume of labels.
>  I have 37 descrete levels.
>  When i load this data imagevis seems to add other levels to the    
> dataset between my labeled regions.                                  
> Is there any way to stop this?

Is this version 2.0.0 or are you building from svn by any chance?
This juuust just changed.  Also, what type are your data (floating
point?)? [1]

Some things of note, regardless of version:

 . if your data are > 16bit, they are quantized to 16bit

 . for large data, we produce a multiresolution hierarchy via a
 downsampling approach which includes averaging.  The averaging can of
 course 'smear' out your flags, especially if they are close together

 . the (visible) histogram behind the transfer functions is computed
 on the lowest resolution data, for performance reasons, but we're
 still doing the correct thing with the higher resolution data,
 despite appearances.

 . We utilize trilinear interpolation during rendering.  This is just
 plain wrong for flag data...

We've heard complaints about that last one before... should really be
fixed.  Gimme a min..

HTH,

-tom

[1] If you have no idea, you can open up ImageVis3D's debug window
(under "Help"), check the 'message' channel, and then try to convert
your dataset.  There will be a message "n-bit XxYxZ data", and then the
message after that will describe the data type.

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