POV-Ray : Newsgroups : povray.beta-test : Difference in height_fields between beta 35 and previous betas or 3.6 : Re: Difference in height_fields between beta 35 and previous betas or 3.6 Server Time
4 Jul 2024 13:33:05 EDT (-0400)
  Re: Difference in height_fields between beta 35 and previous betas or 3.6  
From: Jon Buller
Date: 13 Jan 2010 12:40:01
Message: <web.4b4e03e4bfa4a97d1714f530@news.povray.org>
"Thomas de Groot" <tDOTdegroot@interDOTnlANOTHERDOTnet> wrote:
> I first thought the origin would be the way png images are treated, but the
> same happens with tga. the image_maps are 16 bit gray scale images.

I made a joke about gamma values in p.b.i, but since you are getting your height
values from an image, I might have actually been close.  The valley floor
is flatter, the peaks are sharper, and I would bet money that the new beta is
doing gamma conversion on the height values when reading the image and older
versions didn't.  The image looks a lot like what I did years ago to get a flat
valley floor: square the height values, and typical gamma values are in the 1.8
to 2.2 range.

The quick workaround would be to gamma correct your height field image with a
value of 0.45 or 0.5 before letting the new beta read it in, reversing the new
bug.


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