POV-Ray : Newsgroups : povray.binaries.images : A quick povr branch micro normal image. : Re: A quick povr branch micro normal image. Server Time
22 May 2024 01:05:10 EDT (-0400)
  Re: A quick povr branch micro normal image.  
From: William F Pokorny
Date: 24 Jan 2022 05:51:20
Message: <61ee84a8$1@news.povray.org>
On 1/23/22 07:49, Thomas de Groot wrote:
> Very nice one! More images should "fall out"...

Thanks! :-)

It's on my todo list to aim more often for more complex images! For 
whatever reason I always drift back into chasing things in the code.

Attached is another test image. The one where I first turned up the 
POV-Ray issue with 'too large for our exr reader' channel values in the 
exr HRDI sky_sphere file.

The three spheres are using different normal 'micro' pattern bump sizes. 
Further the scene uses povr's intensity_max control in both the 
reflection block and with the metallic in the overall finish block. The 
latter keeps all the reflected colors in a 0-1 channel range where the 
AA still works.

Most puzzling to me is the upper left sphere where I made the micro 
bump_size large (1.5 I think). It happens once bump_size values get over 
the usual 0.5 limit where normals can start to invert in one or more of 
the x,y,z directions due the perturbation values being so large compared 
to the raw normal values(a). Where perturbed normal inversions occur, 
the result starts to look more like a milky glass. I don't completely 
understand why...

Bill P.

(a) Only a few of povr's normal patterns prevent such inversions - and 
micro doesn't.

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