The "GEO/NOS" file format used by Softchart is essentially the same format. The GEO/NO1 format used by Softchart is the same as GEO/NOS except that a "rot-9" cypher is applied all the data in the file. Wow ... fancy encryption!
The format is not publically documented (except for the patent) but it has been reverse engineered (from the patent description) and free code implemented. The format hasn't been written up.
If you need more information or support on the BSB format you can contact Frank Warmerdam.
More details on the intellectual property issues and my current discussions with MapTech about the legality of distributed BSB reading code are available here. In the meantime those who wish to avoid legal risk are encouraged to *not* use the BSB reading code.
A small distribution of free C/C++ source that can read BSB files (including BSB 1.1, BSB 2.0, BSB 3.0, GEO/NOS, and GEO/NO1), and translate them into a flat raw raster file is available as a tarball or a zip file.
The BSB format code is also incorporated into the GDAL format abstraction library which also reads georeferencing and projection information from the associated header file. Prebuilt version of the gdal_translate utility are available as part of the OpenEV_FW package for Windows and Linux. Fetch the latest OpenEV_FW package from ftp://ftp.remotesensing.org/gdal/openev. The gdal_translate utility might be used like this to convert a BSB file into GeoTIFF format:
gdal_translate -of GTiff 999502.KAP 999502.tifI have recently (Dec2004) learned there is an independently developed open source library called libbsb with a variety of conversion utilities. This can be found at http://libbsb.sf.net.