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<a name="Statistics"></a>Next:&nbsp;<a rel="next" accesskey="n" href="Bugs-and-anomalies.html#Bugs-and-anomalies">Bugs and anomalies</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="Hidden-surface-removal.html#Hidden-surface-removal">Hidden surface removal</a>,
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<h5 class="subsubsection">4.4.3.1 Statistics</h5>

<p>For the curious, <code>sketch</code> writes one line of depth sort
statistics.  Here is an example for a large collection of triangles.
<pre class="verbatim">
  remark, node=34824 probe=581.9 swap=5 split=2 (in=4 out=6) ols=24851/0
</pre>
It means that 34,824 objects were depth sorted after culling. 
For each, an average of 581.9 others had to be checked to
ensure that the initial, approximate ordering was correct.  Among all
these checks, only 5 resulted in swaps to reorder the initial
sort.  In two cases, a correct ordering could not be determined, so
binary space partitions
<a name="index-binary-space-partition-498"></a>were constructed for splitting.  A total of 4
objects (triangles in this case) were inserted in the partitions, and
6 polygons were produced.  Finally, 24,851 &ldquo;last
resort&rdquo; polygon overlap checks were performed after simpler, faster
checks failed to yield conclusive results.  The final /0 is for
line-polygon overlap checks.  For comparison, the statistics for the
last figure in <a href="Overview.html#Overview">Overview</a> follow.
<pre class="verbatim">
  remark, node=27 probe=14.6 swap=36 split=15 (in=30 out=45) ols=0/69
</pre>
Note that there was proportionally much more swapping and splitting
activity in this highly connected scene.

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