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      <title>Topological Information</title>
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      <div class="title_topic3" id="xps10_pagetitle"> Topological Information</div>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_checker.html');return(false);">Check VDA-4955 Compliance Overview</a></p>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_criteria.html');return(false);">Description of the Check Criteria</a></p>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_interact.html');return(false);">Checker Process</a></p>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_config.html');return(false);">Configuration File</a></p>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_check_ov.html');return(false);">Check Criteria</a></p>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_select.html');return(false);">Select Geometry Set</a></p>
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               <p class="para_td">Topological Information</p>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_analysis.html');return(false);">Analysis Run</a></p>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_results.html');return(false);">Results Viewing</a></p>
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               <p class="para_td"> <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_file_usage.html');return(false);">External File Usage</a></p>
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      </table><br><p class="para_topic">Once the geometry set has been defined, it serves as the base of all other investigations that are carried out. The topology engine of the VDA Checker creates adjacency information on demand. Knowledge about one or several connected regions is the result of this computation. Adjacency is computed&nbsp; prior to executing the check routines, which rely on this information. Once the adjacency information is computed, it is retained as long as the selected geometry set is not modified or deleted.</p>
      <p class="para_topic">To give the user an impression of the topological situation before starting an analysis run, for each connected region the outer boundary may be displayed.</p>
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            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
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                  <p class="para_note_body"> For solid bodies, there is no outer boundary under normal circumstances. In case boundaries are displayed this may result from gaps exceeding the Topological Tolerances | Distance, or from tiny faces near modelling tolerance. </p>
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      <p class="para_topic">You can force the creation or renewal of topological information (Create/Renew Topology). For Number of Edge Curve Points, the topology engine evaluates the distance between two common edge curve candidates, and checks this distance against Topological Tolerances | Distance. A Topological Tolerance defines an upper threshold value beyond which a continuity check criterion violation is neither considered a violation nor logged in the Results Log File. A topological tolerance is defined for distance, angle and curvature for GC0, GC1 and GC2 continuity across surface or segment boundaries, respectively. </p>
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               <p class="para_td">Control</p>
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               <p class="para_td">Description</p>
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               <p class="para_td">Create/Renew Topology</p>
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               <p class="para_td">Force a reevaluation of the topology.</p>
               <p class="para_td">This control is enabled if the face Geometry Set is not empty. </p>
               <p class="para_td">This control can be used to (re)display the temporary markers of outer boundaries. Any temporary markers from previous actions will be deleted after a View&rarr; Refresh.</p>
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               <p class="para_td">Display Topology</p>
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               <p class="para_td">Control the display of the topological situation.</p>
               <p class="para_td">If selected, for each connected region the outer boundary is displayed by a series of temporary markers.</p>
               <p class="para_td">This option is enabled or disabled according to the setting of the Faces option under  <a class="links" href="javascript:void(0)" onclick="top.openFile('nx_analysis/vda_check_ov.html');return(false);">Check Criteria</a>.
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               <p class="para_td">The intended use of the Create/Renew Topology and Display Topology control is to evaluate and display the topology prior to an analysis run. This may help you to decide if the current Geometry Set can reasonably be used for further checking.</p>
               <p class="para_td">When changing the Topological Tolerances/Distance, the outer boundaries may change, because the treatment of adjacent edges may change from connected to unconnected, and vice versa.</p>
               <p class="para_td">The sampling rate of the temporary markers can be increased by increasing the Number of Edge Curve Points. A minimum of nine markers per edge is displayed.</p>
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            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
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                  <p class="para_note_body">When using All in Partfile for selection, these controls remain disabled until the analysis run is complete. Because of the batch-like behaviour of All in Partfile selection, there are no elements filled into the geometry set before clicking the Apply or OK buttons. For topology checking, it is better to select using Faces &rarr; Select All. </p>
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