POV-Ray : Newsgroups : povray.binaries.images : tricubic grid interpolation : Re: tricubic grid interpolation Server Time
8 Aug 2024 22:14:59 EDT (-0400)
  Re: tricubic grid interpolation  
From: andrel
Date: 28 Apr 2005 12:42:24
Message: <427111E8.1040700@hotmail.com>
andrel wrote:
> triple_r wrote:
> 
>> Also, the small cube is the voxel containing the point to be 
>> interpolated,
>> the larger cube is the 26 surrounding cubes.
> 
> 
> Ok, I didn't get that. Now you mention it is is sort of obvious.
> Only, this means that tricubic interpolation is fixed by the
> coordinates of the grid points on this center voxel and the
> surrounding grid points. You will not be able to get continuity
> in any of the edges and faces of the voxels. Take for instance
> the upper blue point on the green line. If you approach it from
> the underside, from within the grey area, you will find another
> point in space after interpolation than if you approach it from
> the outside. 
NB I implicitly assumed that the idea was to use the 3 by 3 surround
of a voxel to compute the interpolation within that voxel.
If you repartition the entire volume in 3 by 3 voxel 'supervoxels'
then you will have voxels that fit together. However, all derivatives
may be discontinuous at the joining surface.


Post a reply to this message

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.