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    <td width="234"><a href="http://pixie.sourceforge.net"><img border="0" src="logo.jpg" width="234" height="98"></a></td>
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	<p align="center"><font face="Tahoma" size="7">Hiders</font></td>
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    <td width="234"></td>
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<hr>

<p>Pixie can generate images using raytracing or scan line rendering. As it is
often the case, scan line rendering is much faster than raytracing. However,
such methods may not support accurate reflections/shadows. Since Pixie supports
both types of algorithms, you can combine the best of the two worlds: speed of
scan-line rendering and the accuracy of raytracing. A hider is the section of
the renderer that is responsible for creating the final image. Essentially,
every hider implements a different rendering algorithm. You can switch between
defined hiders using&nbsp; Hider command. Pixie defines the following hiders:</p>
<table border="0" width="100%">
  <tr>
    <td width="183" bgcolor="#CCFF99"><b><font face="Courier New">raytrace</font></b></td>
    <td width="1269">As the name implies, this hider creates the final image
      using raytracing. This involves shooting bunch of rays for every pixel
      (defined by&nbsp; <font face="Courier New">PixelSamples</font>) and then filtering and summing the color
      of every ray (defined by&nbsp; <font face="Courier New">PixelFilter</font>).<p>&nbsp;</td>
  </tr>
  <tr>
    <td width="183" bgcolor="#CCFF99"><b><font face="Courier New">stochastic/hidden</font><br>
      (Default)</b></td>
    <td width="1269">This hider creates the final image using scan-line
      techniques very similar to Pixar's Reyes architecture. Every specified primitive is split into smaller primitives and
      deferred until needed. If the projected size of a subdivided primitive is
      small enough, a regular grid is sampled on the patch and the polygons in
      this grid are rendered using scan-line methods. Notice that a raytracer
      may need to keep the entire scene geometry in the memory in case a future
      ray can intersect them. On the other hand, the deferred and
      render-and-forget feature of this rendering algorithm allows it to keep a
      very small memory footprint<p>&nbsp;</td>
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  <tr>
    <td width="183" bgcolor="#CCFF99"><b><font face="Courier New">zbuffer</font></b></td>
    <td width="1269">This hider is a stripped down version of <b>Stochastic</b>.
      It does not support motion blur, depth of field or transparency. If your
      scene does not involve these effects, this hider can generate an equal
      quality output with the <b>Stochastic</b>.<p>&nbsp;</td>
  </tr>
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    <td width="183" bgcolor="#CCFF99"><b><font face="Courier New">opengl</font></b></td>
    <td width="1269">This is exactly the same with <b> Zbuffer</b>. However, the final
      stage of the rendering is implemented with <b> OpenGl</b>. The potential hardware
      acceleration makes this hider much faster than any other hider. If your
      computer does not have a hardware implemented opengl driver, <b>Zbuffer</b>
      is faster. <b>OpenGL</b> hider is only available on Windows systems for
      the time being.<p>&nbsp;</td>
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  <tr>
    <td width="183" bgcolor="#CCFF99"><b><font face="Courier New">photon</font></b></td>
    <td width="1269">This hider is used to compute photonmaps in a preprocessing
      step. This hider does not create an image. The renderer simply goes
      through the light sources defined in a scene and shoots photons.</td>
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</table>
<p>If you notice,&nbsp; OpenGL hider is implemented as a module. That means if
you want to use it,&nbsp; <b>opengl.dll/so</b> must be in your procedural path (check&nbsp;<font face="Courier New">
&quot;searchpath&quot; &quot;procedural&quot;</font> option).</p>
<p>The following table summarizes the capabilities of each hider:</p>
<table border="1" cellspacing="0" bordercolor="#000000" bordercolordark="#000000" cellpadding="0" width="652">
  <tr>
    <td>&nbsp;</td>
    <td width="58" bgcolor="#CCCCCC" align="center">TSM</td>
    <td width="49" bgcolor="#CCCCCC" align="center">J</td>
    <td width="43" bgcolor="#CCCCCC" align="center">T</td>
    <td width="51" bgcolor="#CCCCCC" align="center">OC</td>
    <td width="64" bgcolor="#CCCCCC" align="center">AOS</td>
    <td width="57" bgcolor="#CCCCCC" align="center">SS</td>
    <td width="54" bgcolor="#CCCCCC" align="center">MB</td>
    <td width="56" bgcolor="#CCCCCC" align="center">DOF</td>
    <td bgcolor="#CCCCCC" align="center">LOD</td>
  </tr>
  <tr>
    <td bgcolor="#CCFF99">stochastic</td>
    <td width="58" align="center"><font face="Courier New">X</font></td>
    <td width="49" align="center"><font face="Courier New">X</font></td>
    <td width="43" align="center"><font face="Courier New">X</font></td>
    <td width="51" align="center"><font face="Courier New">X</font></td>
    <td width="64" align="center"><font face="Courier New">X</font></td>
    <td width="57" align="center"><font face="Courier New">X</font></td>
    <td width="54" align="center"><font face="Courier New">X</font></td>
    <td width="56" align="center"><font face="Courier New">X</font></td>
    <td align="center"><font face="Courier New">X</font></td>
  </tr>
  <tr>
    <td bgcolor="#CCFF99">raytrace</td>
    <td width="58" align="center">&nbsp;</td>
    <td width="49" align="center"><font face="Courier New">X</font></td>
    <td width="43" align="center"><font face="Courier New">X</font></td>
    <td width="51" align="center">&nbsp;</td>
    <td width="64" align="center"><font face="Courier New">X</font></td>
    <td width="57" align="center"><font face="Courier New">X</font></td>
    <td width="54" align="center"><font face="Courier New">X</font></td>
    <td width="56" align="center"><font face="Courier New">X</font></td>
    <td align="center">X</td>
  </tr>
  <tr>
    <td bgcolor="#CCFF99">zbuffer</td>
    <td width="58" align="center">&nbsp;</td>
    <td width="49" align="center">&nbsp;</td>
    <td width="43" align="center">&nbsp;</td>
    <td width="51" align="center"><font face="Courier New">X</font></td>
    <td width="64" align="center">&nbsp;</td>
    <td width="57" align="center"><font face="Courier New">X</font></td>
    <td width="54" align="center">&nbsp;</td>
    <td width="56" align="center">&nbsp;</td>
    <td align="center">&nbsp;</td>
  </tr>
  <tr>
    <td bgcolor="#CCFF99">opengl</td>
    <td width="58" align="center">&nbsp;</td>
    <td width="49" align="center">&nbsp;</td>
    <td width="43" align="center">&nbsp;</td>
    <td width="51" align="center">&nbsp;</td>
    <td width="64" align="center">&nbsp;</td>
    <td width="57" align="center"><font face="Courier New">X</font></td>
    <td width="54" align="center">&nbsp;</td>
    <td width="56" align="center">&nbsp;</td>
    <td align="center">&nbsp;</td>
  </tr>
  <tr>
    <td bgcolor="#CCFF99">photon</td>
    <td width="58" align="center">&nbsp;</td>
    <td width="49" align="center">&nbsp;</td>
    <td width="43" align="center">&nbsp;</td>
    <td width="51" align="center">&nbsp;</td>
    <td width="64" align="center">&nbsp;</td>
    <td width="57" align="center">&nbsp;</td>
    <td width="54" align="center">&nbsp;</td>
    <td width="56" align="center">&nbsp;</td>
    <td align="center">&nbsp;</td>
  </tr>
</table>
<p>Where:</p>
<table border="0" bordercolorlight="#FFFFFF" width="352">
  <tr>
    <td width="68" bgcolor="#CCCCCC">TSM</td>
    <td width="270">Transparency Shadow Map</td>
  </tr>
  <tr>
    <td width="68" bgcolor="#CCCCCC">J</td>
    <td width="270">Jittering</td>
  </tr>
  <tr>
    <td width="68" bgcolor="#CCCCCC">T</td>
    <td width="270">Transparency</td>
  </tr>
  <tr>
    <td width="68" bgcolor="#CCCCCC">OC</td>
    <td width="270">Occlusion Culling</td>
  </tr>
  <tr>
    <td width="68" bgcolor="#CCCCCC">AOS</td>
    <td width="270">Arbitrary Output Samples</td>
  </tr>
  <tr>
    <td width="68" bgcolor="#CCCCCC">SS</td>
    <td width="270">Super Sampling</td>
  </tr>
  <tr>
    <td width="68" bgcolor="#CCCCCC">MB</td>
    <td width="270">Motion Blur</td>
  </tr>
  <tr>
    <td width="68" bgcolor="#CCCCCC">DOF</td>
    <td width="270">Depth Of Field</td>
  </tr>
  <tr>
    <td width="68" bgcolor="#CCCCCC">LOD</td>
    <td width="270">Level Of Detail</td>
  </tr>
</table>

<hr>
<p>The
      RenderMan (R) Interface Procedures and RIB Protocol are: Copyright 1988,
      1989, Pixar. </p>

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