307 lines
8.2 KiB
HTML
307 lines
8.2 KiB
HTML
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="GENERATOR" content="Mozilla/4.77 [en] (X11; U; Linux 2.4.3-20mdk i686) [Netscape]">
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<title>Native stereo support</title>
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</head>
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<body text="#000000" bgcolor="#FFFFFF" link="#0000EE" vlink="#551A8B" alink="#FF0000">
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<img SRC="images/OpenSceneGraphBanner_Distribution.jpg" height=77 width=640>
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<table>
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<tr>
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<td><a href="index.html">Index</a></td>
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<td><a href="introduction.html">Introduction</a></td>
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<td><a href="contents.html">Contents</a></td>
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<td><a href="install.html">Install</a></td>
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<td><a href="dependencies.html">Dependencies</a></td>
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<td><a href="demos.html">Demos</a></td>
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<td><a href="data.html">Data</a></td>
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<td><a href="sgv.html">Viewer</a></td>
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<td><a href="stereo.html">Stereo</a></td>
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<td><a href="plan.html">Plan</a></td>
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<td><a href="documentation.html">Reference Guides</a></td>
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</tr>
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</table>
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<h2>
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<u>Native Support for Stereo</u></h2>
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The OSG has support for anaglyphic stereo (i.e. red/green or red/cyan glasses),
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quad buffered stereo (i.e. active stereo using shutter glasses, or passive
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stereo using polarized projectors & glasses) and horizontal and vertical
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split window stereo implementations. Almost all OSG applications have the
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potential for stereo support simply by setting the relevant environmental
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variables, or via command line arguments. Little or no code changes will
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be required, the support is handled transparently inside osgUtil::SceneView's
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handling of rendering. It is a simple as:
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<br><b> sgv -stereo cow.osg</b>
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<p>If the user is planning to use head tracked stereo, or a cave then it
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is currently recommend to set it up via a VR toolkit such as VRjuggler,
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in this case refer to the VR toolkits handling of stereo, and keep all
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the OSG's stereo specific environment variables (below) set to OFF, or
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set the values to off within own your own applications.
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<br>
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<hr>
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<h3>
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The environmental variables of interest:</h3>
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<table>
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<tr>
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<td><b>OSG_STEREO</b></td>
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<td><b>ON</b></td>
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<td>Turn stereo on </td>
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</tr>
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<tr>
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<td></td>
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<td><b>OFF</b></td>
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<td>Turn stereo off (default). </td>
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</tr>
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<tr>
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<td><b>OSG_STEREO_MODE</b></td>
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<td><b>ANAGLYPHIC</b></td>
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<td>Use anaglyphic stereo when in stereo (default). </td>
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</tr>
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<tr>
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<td></td>
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<td><b>QUAD_BUFFER</b></td>
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<td>Use quad buffered stereo when in stereo. </td>
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</tr>
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<tr>
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<td></td>
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<td><b>HORIZONTAL_SPLIT</b></td>
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<td>Use horizontal split stereo mode when in stereo </td>
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</tr>
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<tr>
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<td></td>
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<td><b>VERTICAL_SPLIT</b></td>
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<td>Use vertical split stereo mode when in stereo </td>
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</tr>
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<tr>
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<td><b>OSG_SCREEN_DISTANCE</b></td>
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<td><b>0.50</b></td>
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<td>Set the distance the viewer is from screen in metres (default shown) </td>
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</tr>
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<tr>
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<td><b>OSG_SCREEN_HEIGHT</b></td>
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<td><b>0.26</b></td>
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<td>Set the height if image on the screen in metres (default shown) </td>
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</tr>
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<tr>
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<td><b>OSG_EYE_SEPARATION</b></td>
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<td><b>0.06</b></td>
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<td>Set the eye separation - interoccular distance (default shown.) </td>
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</tr>
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<tr>
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<td><b>OSG_SPLIT_STEREO_HORIZONTAL_SEPARATION</b></td>
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<td><b>42</b></td>
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<td>Set the number of pixels between the left and right viewports (default
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shown).</td>
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</tr>
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<tr>
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<td><b>OSG_SPLIT_STEREO_HORIZONTAL_EYE_MAPPING</b></td>
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<td><b>LEFT_EYE_LEFT_VIEWPORT</b></td>
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<td>Set the left eye to render to left viewport, right eye to right viewport
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(default). </td>
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</tr>
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<tr>
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<td></td>
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<td><b>LEFT_EYE_RIGHT_VIEWPORT</b></td>
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<td>Set the left eye to render to right viewport, right eye to left viewport. </td>
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</tr>
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<tr>
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<td><b>OSG_SPLIT_STEREO_VERTICAL_SEPARATION</b></td>
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<td><b>42</b></td>
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<td>Set the number of pixels between the top and bottom viewports (default
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shown).</td>
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</tr>
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<tr>
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<td><b>OSG_SPLIT_STEREO_VERTICAL_EYE_MAPPING</b></td>
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<td><b>LEFT_EYE_TOP_VIEWPORT</b></td>
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<td>Set the left eye to render to top viewport, right eye to bottom viewport
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(default). </td>
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</tr>
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<tr>
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<td></td>
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<td><b>LEFT_EYE_BOTTOM_VIEWPORT</b></td>
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<td>Set the left eye to render to bottom viewport, right eye to top viewport. </td>
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</tr>
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</table>
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<hr>
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<h3>
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Command line arguments can be used to override these settings:</h3>
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<table>
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<tr>
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<td><b>-stereo</b></td>
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<td></td>
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<td>Switch on stereo. </td>
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</tr>
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<tr>
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<td><b>-stereo</b></td>
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<td><b>ON</b></td>
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<td>Switch on stereo. </td>
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</tr>
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<tr>
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<td></td>
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<td><b>OFF</b></td>
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<td>Switch off stereo. </td>
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</tr>
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<tr>
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<td></td>
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<td><b>ANAGLYPHIC</b></td>
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<td>Switch on ANAGLYPHIC stereo. </td>
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</tr>
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<tr>
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<td></td>
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<td><b>QUAD_BUFFER</b></td>
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<td>Switch on QUAD_BUFFER stereo. </td>
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</tr>
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<tr>
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<td></td>
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<td><b>VERTICAL_SPLIT</b></td>
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<td>Switch on VERTICAL_SPLIT stereo. </td>
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</tr>
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<tr>
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<td></td>
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<td><b>HORIZONTAL_SPLIT</b></td>
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<td>Switch on VERTICAL_SPLIT stereo. </td>
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</tr>
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</table>
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<hr>
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<h3>
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Examples:</h3>
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To invoke stereo from the comandline:
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<br><b> sgv -stereo cow.osg</b>
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<p>To invoke quad buffered stereo from the commandline:
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<br><b> sgv -stereo QUAD_BUFFER cow.osg</b>
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<p>To force all apps to start up in quad buffered stereo (if system supports
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it)
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<br><b> export OSG_STEREO=ON</b>
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<br><b> export OSG_STEREO_MODE=QUAD_BUFFER</b>
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<br><b> sgv cow.osg</b>
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<p>To set quad buffered stereo to the default, but use the commandline
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to switch stereo on:
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<br><b> export OSG_STEREO=OFF</b>
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<br><b> export OSG_STEREO_MODE=QUAD_BUFFER</b>
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<br><b> sgv -stereo cow.osg</b>
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<p>
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<hr>
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<h3>
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Size matters:</h3>
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For appropriate depth perception the stereo code creates separate left
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and eye views, both the frustum and modelview are shifted to account for
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the separate eye views. To achieve the right amount of adjustment
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the OSG requires the users eye separation, the distance from the eyes to
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the screen and the height of the screen. The OSG will use the defaults
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of 0.05m,0.5m and 0.26m respectively which are assumed to be reasonable
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defaults for most users workstation configurations, note the OSG_SCREEN_HEIGHT
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is the image height rather than total size of your monitor/display surface.
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For the best stereo effects please measure these values and set them up
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via the environmental variables. Once set the views you get should
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give improved depth perception. A good way of measuring how well
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you are configured for your display is to fly away from objects (using
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the FlightManipulator for instance, but not the TrackballManipulator, see
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below) so that they go of toward infinity. As they move away the offset
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between the two images should tend towards your eye separation, if you
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achieve this then the object will be perceived as at infinity.
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<br>
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<hr>
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<h3>
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Camera Manipulator Modes:</h3>
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There are three osgUtil::CameraManipulator's which come with osgUtil, which
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operate as a Trackball, Drive and Flight modes of interaction (see sgv.html
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for how to invoke them in the scene graph viewer). The osgUtil::Trackball
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Manipulator automatically scales the fusion distance to that which will
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fusion on center point of rotation - this will appear at the middle of
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the monitor at the monitors depth. Whereas, the osgUtil::DriveManipualtor,
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osgUtil::FlightManipulator scale the fusion distance to the distance the
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viewer is from the screen, the results in a perception that the virtual
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world is scaled to physical world, this is clearly better for simulators
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and alike. You can control the fusion of the image in these two modes via
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the osg::Camera::setFusionDistanceMode(FusionDistanceMode mode) where mode
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can be osg::Camera::PROPORTIONAL_TO_LOOK_DISTANCE (used by Trackball) or
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osg::Camera::PROPORTIONAL_TO_SCREEN_DISTANCE (used by Drive and Flight),
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and osg::Camera::setFusionDistanceRatio(float). See include/osg/Camera
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for further details, and the camera manipulators for implementation details.
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The fusion distance ratio defaults to 1.0 but can be biased to move objects
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out or into screen, they will also appear to get smaller and larger respectively.
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The camera manipulators allow the user to alter this value at runtime via
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the '+' and '-' keys.
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</body>
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</html>
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