[Bf-docboard] Correction for Lighting chapter

[Ton Roosendaal]

Hi,

The bias value represents a distance, from which a gradual transition  
is calculated between 100% shadow and 100% light. Especially with  
low-res shadow-buffers you can see that faces tend to be in its own  
shadow a bit - typically visible as 'rings' or 'banding' - this  
inaccuracy then can be solved by increasing the bias value.

BTW:
What someone could try is introducing an exta 'offset' value, which is  
added before calculating bias... hrms, this offset can even be  
calculated automatically with the pixel size of a shadowbuffer...  
(640x640 buffer: offset= z-depth/640). hrms...

(intrr: your spam filter still refuses mail from me!)

-Ton-

On Saturday, May 31, 2003, at 15:49 Europe/Amsterdam, instinctive new  
media wrote:

>
>
> Hi,
>
> after reading the chapter on lighting, I'm not quite sure if the  
> description
> of the "Bias" value is correct.
>
> I might be wrong, but in my opinion it just shifts the shadows back and
> forth from the lamp to account for inaccuracies. It does _not_ improve
> shadow quality, it's merely a corrective measure.
>
> Tell me if I'm wrong.
>
> | alexander ewering           instinctive new media
> | ae@instinctive.de       http://www.instinctive.de
> |
> | fon: +49-2393-220558         fax: +49-2393-220559
>
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>
------------------------------------------------------------------------ 
--
Ton Roosendaal  Blender Foundation ton@blender.org