Re: Volume visualization strangeness

• To: Bill Hibbard <billh@xxxxxxxxxxxxx> <curtis@xxxxxxxxxxxxx>, visad-list@xxxxxxxxxxxxx, dwd@xxxxxxxxxxxxx
• Subject: Re: Volume visualization strangeness
• From: John Osborne <John.Osborne@xxxxxxxx>
• Date: Fri, 14 Feb 2003 09:17:05 -0800

Bill,

Looks like you're saying this is a feature. My concerns with resampling
the grid to make things cubic are that I'm going to pay a large memory
penalty (maore than an order of magnitude greater in the case of the
61x61x5 example) and I risk aliasing the original grid. In addition,
users of ncBrowse will be stuck with how I choose to resample the grid. 

----- Original Message -----
From: Bill Hibbard <billh@xxxxxxxxxxxxx>
Date: Thursday, February 13, 2003 3:41 pm
Subject: Re: Volume visualization strangeness

> Hi John,
> 
> > You are right--changing the aspect ratio didn't fix the 
> problem.. So is
> > the rendering problem with non-cubic grids a VisAD bug or VisAD 
> feature?
> VisAD implements volume rendering as sets of planes perpendicular
> to the X, Y and Z axes. The choice of axis changes as the box
> rotates, to the axis closest to parallel with the view direction.
> This techniques is widely used (and first described in my paper
> to the 1989 volume visualization workshop), but does produce weird
> images when volumes are very non-square like your 61 x 61 x 5. Try
> Curtis's suggestion of resampling to 61 x 61 x 61.
> 
> Cheers,
> Bill
> 
> 

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    • From: Bill Hibbard