[osg-users] vpb on cluster example

Robert Osfield robert.osfield at gmail.com
Wed Jul 23 05:34:27 PDT 2008


Hi J.P.

Many thanks for putting this guide, sure saves me some time and will
help others.

In terms of the work flow, there are couple of things that VPB can
help out with.

As you note, vpbmaster doesn't like, or actually does not permit
building on databases where the source data is in different
coordinates system, this is due to the fact that the parallel osgdem
runs would end up doing the reprojection themselves each time, which
is both a waste of compute resources as well as a threading issue.
Since vpbmaster has this requirement, we have a another tool that can
do the reprojection for use - vpbcache.

The vpbcache app can create a file cache that contains a mapping
between your original source data and reprojected versions of it.  The
vpbcache tool allows you to create this file cache, and then to do the
reprojection that is required for the final build.   vpbcache takes as
input a source file, typically exactly the same source file that
vpbmaster run will use.

So what's this about source files....  we'll this is an ascii file
that wraps up all the source data and build options that will use.
vpbmaster creates a source file and then passes this on to the slaves
so they no what to process. You can also get vpbmaster to generate a
master source file for you.

The rough process is :

Step 1:

   run vpbmaster with all your source files and then get it to output
a build.source file, this run does not run the
   actual build.  Add --so build.source to the command line to output
the source file.

Step 2:

   run vpbcache with the build.source file, to create a cache file

Step 3:

   run vpbcache to reproject the source files into the required
coordinates system for the build

Step 4:

   run vpbmaster with the cache file, and the build.source file, and a
master file describing the layout of
   your cluster

Step 5:

   Wait :-)

I'm afraid I don't recall the options off the top of my head...

Robert.



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