[osg-users] vpb on cluster example

J.P. Delport jpdelport at csir.co.za
Wed Jul 23 05:47:44 PDT 2008


Hi,

Robert Osfield wrote:
> 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.

OK cool, I was wondering what the whole cache thing was about :)

> 
> 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 must say that the new vpb with --terrain is a _lot_ faster than the 
old osgdem used to be. One can now generate quite a bit of data over a 
weekend :)

jp

> 
> I'm afraid I don't recall the options off the top of my head...
> 
> Robert.
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
> 

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