You will need GDAL, its dependencies, and the MrSID plugin for the GDAL framework. If you are on a MAC, the easiest way to get GDAL and the utilities is as pre-compiled binaries available from Kyng Chaos. One of those utilities, gdal_translate, does exactly what we need. Enter GDAL, an open-source GIS library which comes with some useful command-line utilities. What I wanted to do was convert the entire map to one large raster file.
Lizard Tech has some Mac utilities which allow one to view the files, but nothing I could find which would extract the high-resolution sections that I needed. This is great for streaming tiles of a larger image, but not so great if you need a large hi-resolution version of all or most of the data. It is useful because it allows software to request various sections and resolutions quickly without decompressing the entire image. MrSID (Multi-Resolution Seamless Image Database) is a highly compressed format for rasterized GIS data.
I have a disk with a USGS topographic map of an area, but on the Mac OS X platform, it is difficult to find a utility capable of working with the MrSID file format in which the maps are encoded. I spent too much time searching for a solution to this problem, so I thought I'd add a note here for the next person googling for a solution.
