[M4IF Technotes] MatteTexture

[axel.binder philips.com]

Hi together,
I found some drafts on MatteTexture and figured that the reveal blending 
mode
is similar to MaterialKey (apart from the threshold value calculation).
Now I want to point out two issues regarding the surface selection 
(depending on the threshold):
- for sharp surface transitions (no softness value) surface 1 is defined 
for alphas less than the threshold
  while surface 2 is defined for alphas greater than the threshold. To my 
understanding that leaves
  an undefined state for alphas equal to the threshold (at least in cases 
where the threshold is an integer).
- blending both surfaces in a softness range defines 
      surface 1 for alphas <= lower threshold
      surface 2 for alphas >= upper threshold
      linear blending for lower threshold < alpha < upper threshold.
  This is a valid definition as long as the lower and upper threshold are 
not identical.
  It would be much more robust to define
     surface 1 for alphas <= lower threshold
     surface 2 for alphas > upper threshold
     linear blending for lower threshold < alpha <= upper threshold
  (and a similar definition for the first case).
  As a side effect that would unify this aspect of the blending with 
MaterialKey and
  thus simplify implementation.
I have no idea how mature the MatteTexture feature is right now, but maybe 
somebody
involved might consider it.
regards
axel binder
=======================================================
Axel Binder                                              Philips Starnberg 
(SP3D)
Development Manager Software    Petersbrunner Str. 17
 D-82319 Starnberg, Germany
phone:  +49 8151 270 108 
fax:         +49 8151 270 200
mobile: +49 172 92 18 623
e-mail: axel.binder   philips.com
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