Commit babb1093 authored by Cory Quammen's avatar Cory Quammen

Added section on Ghost Cells Generator

parent 8094b04c
......@@ -528,7 +528,6 @@ advantage we had with parallel processing. Because ghost cells are used so
frequently, random partitioning is not used in ParaView.
\subsection{D3 Filter}
\fixme{Replace with section on Ghost Cells Generator filter}
The previous section described the importance of load balancing and ghost
levels for parallel visualization. This section describes how to achieve
......@@ -568,6 +567,25 @@ left, we see that there are many faces improperly extracted because we are
missing ghost cells. On the right, the problem is fixed by first using the
D3 filter.
\section{Ghost Cells Generator}
If your unstructured grid data is already partitioned satisfactorily but does
not have ghost cells, it is possible to generate them using the \ui{Ghost Cells Generator}
filter. This filter can be attached to a source just like the \ui{D3} filter.
Unlike \ui{D3}, it will not repartition the data set, it will only generate
ghost cells, which is needed for some algorithms to execute correctly.
The \ui{Ghost Cells Generator} has several options. \ui{Build If Required}
tells the filter to generate ghost cells only if required by a downstream filter.
Since computing ghost cells is a computationally and communications intensive
process, turning this option on can potentially save a lot of processing time.
The \ui{Minimum Number Of Ghost Levels} specifies at least how many ghost levels
should be generated if \ui{Build If Required} is off. Downstream filters may request
more ghost levels than this minimum, in which case the \ui{Ghost Cells Generator}
will generate the requested number of ghost levels. The \ui{Use Global Ids} option
makes use of a GlobalIds array if it is present if on. If off, ghost cells are
determined by coincident points.
\section{ParaView architecture}
Before we see how to use ParaView for parallel data processing, let's take a
......@@ -684,8 +702,6 @@ command \texttt{mpirun -np 4 pvserver}.}
\label{fig:SphereColoredByProcessId}
\end{figure}
\fixme{Change to D3}.
If a data reader or source is not ``parallel aware'', you can still get
the benefits of spreading the data among processing cores by using the
\ui{D3} filter. This filter partitions a dataset into convex regions
......
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