[osg-users] Blue Marble example

[Michael W. Hall]

I am looking at the Blue Marble example that come with the source.  I
have a question about the createWorld function.  The first line of the
function they are getting a readerwriter.  They make a call to
getReaderWriterForExtension("gdal").  What is this extension and how do
you know what extensions to pass in?  Is there a list of them somewhere?