[OpenWalnut-Dev] [OpenWalnut - Bug #40] (In Progress) Colormap for vector texture is still only correct if not interpolated

[Sebastian Eichelbaum]

Hi Alex

What exactly do you want to do to fix this? As you set this ticket to "in progress" I assume you are working on it?

Bye
Sebastian

On Sun, 09 Oct 2011, redmine at openwalnut.com wrote:

> 
> Issue #40 has been updated by Alexander Wiebel.
> 
> Status changed from New to In Progress
> % Done changed from 0 to 10
> 
> 
> ----------------------------------------
> Bug #40: Colormap for vector texture is still only correct if not interpolated
> http://www.openwalnut.org/issues/40
> 
> Author: Anonymous
> Status: In Progress
> Priority: Normal
> Assignee: Alexander Wiebel
> Category: OpenWalnut  1.3
> Target version: OpenWalnut 1.3
> 
> 
> Meaning we have many small artifacts which are black lines. They result from interpolation of opposing directions as Sebastian commented the following in the old ticket system:
> 
>  _This is because vectors are assumed to be in [0,1] in each component. This is simply wrong. It is fixed in my personal repo and will be merged
> soon. A general problem stays. How to show negative vector components? Maybe someone can post some document where this is addressed explicitly._
> 
> 
> Alex commented: 
> 
>  _It seems that scaling them to [0,1] does not help alone even if negative values are handled correctly. I have a solution that works nearly.
> The remaining problem is that interpolation of the vectors does not work properly because they can point in opposite directions if they are
> eigenvectors._
> 
> and:
> 
>  _Ok, it works if I turn off interpolation of the texture. As a first solution this will be the default for vector data sets. For interpolated
> textures there is still the problem of interpolating between eigenvectors of different sign. See attached image. This is left as future task._
> 
> !VectorDataSet_as_default_texture_uninterpolated.png! !VectorDataSet_as_texture_interpolated.png! 
> 
> 
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-- 
Dipl.-Inf. Sebastian Eichelbaum
Universität Leipzig
Institut für Informatik
Abteilung Bild- und Signalverarbeitung
PF 100920
D-04009 Leipzig