[Bf-docboard] UPDATE: section_anti_aliasing.xml

[Stefano Selleri]

Cool!

/me swears to include this soon, not after a week like last time

Stefano
----- Original Message ----- 
From: "Kenneth Styrberg" <kenneth.styrberg at telia.com>
To: "Blender Documentation Project" <bf-docboard at projects.blender.org>
Sent: Wednesday, January 05, 2005 12:55 AM
Subject: [Bf-docboard] UPDATE: section_anti_aliasing.xml


> Added the Gauss option to the section. Also added/updated one figure.
>
> //Kenneth
>
>


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> <!-- antialiasing -->
> <section id='rendering_antialiasing'>
> <title>Antialiasing</title>
>
> <para>
> <emphasis>Relevant to Blender v2.32</emphasis>
> </para>
>
> <para>
> A computer generated image is made up of pixels, these
> pixels can of course only be a single colour. In the rendering
> process the rendering engine must therefore assign a single
> colour to each pixel on the basis of what
> object is shown in that pixel.
>   </para>
> <para>
> This often leads to poor results, especially at sharp
> boundaries, or where thin lines are present, and it is
> particularly evident for oblique lines.
> </para>
> <para>
> To overcome this problem, which is known as <emphasis>Aliasing</emphasis>,
> it is possible to resort to an
> Anti-Aliasing technique. Basically, each pixel is 'oversampled',
> by rendering it as if it were 5 pixels or more, and assigning
> an 'average' colour to the rendered pixel.
> </para>
> <para>
> The buttons to control Anti-Aliasing, or OverSAmple (OSA), are
> below the rendering button in the <literal>Render</literal>
> Panel (<xref linkend="BSG.REN.F.KST.RE01"/>).
> By pressing the <keycap>OSA</keycap>
> button antialiasing is activated, by selecting one of the four
> numeric buttons below it, the level of oversampling (from 5 to 16)
> is chosen.
> </para>
>
> <figure id="BSG.REN.F.KST.RE01" float="1">
>   <title>Render Panel.</title>
>   <mediaobject>
>     <imageobject>
> <imagedata fileref="PartR/rendering/gfx/renderPanel.png" format="PNG"/>
>     </imageobject>
>   </mediaobject>
> </figure>
>
> <para>
> Blender uses a Delta Accumulation rendering system with jittered sampling.
> The values of <literal>OSA</literal> (5, 8, 11, 16) are pre-set
> numbers that specify
> the number of samples; a higher value produces better edges, but slows
> down the rendering.
> </para>
> <para>
> Another parameter that can improve picture quality when using OSA is the
> <literal>Gaussian filter</literal> parameter, also located in the
<literal>
> Render</literal> panel. By pressing the <keycap>Gauss</keycap> button
> the filter is activated. The number slider to the right of the <literal>
> Gauss</literal> button defines the size of the sample mask. The sub-pixel
> sample creates a small weighted mask with the defined size, which also can
> affect neighbouring pixels as well.
> The result is smoother edges, less sensitive for gamma, and well suited
> to reduce motion-aliasing. (<xref linkend="BSG.REN.F.KST.RE01"/>)
> </para>
>
> <note>
> <para>
> Currently the Gauss option only works for edges of normal faces. It
> does not work for transparent rendering, or to solve high frequency
> aliasing from ray trace render, or for the Unified render.
> </para>
> </note>
>
> <para>
> <xref linkend="BSG.REN.F.S68.302"/> shows a rendering with OSA turned
>   off and with 5 or 8 OSA samples.
> </para>
>
> <figure id="BSG.REN.F.S68.302" float="1">
>   <title>Rendering without OSA (left) with OSA=5 (center) and OSA=8
(right).</title>
>   <mediaobject>
>     <imageobject>
> <imagedata fileref="PartR/rendering/gfx/AA02.png" format="PNG"/>
>     </imageobject>
>   </mediaobject>
> </figure>
> </section>
>
>


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