NOAA/MAPTECH/NDI/SoftChart BSB

The BSB format is a compressed raster format used for distributing raster nautical charts by various organizations in North America, notable MapTech and NOAA.

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.

Intellectual Property Issues

The compression method used to produce BSB is copyrighted, but it would seem that this does not apply to decompressing BSB files. Also, Maptech claims the file format is copyright.

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.

Example Source

Unfortunately, I no longer have a convenient package with the BSB code but it is still in development within GDAL and it can be found at http://svn.osgeo.org/gdal/trunk/gdal/frmts/bsb. The most relavent low level parts are bsb_read.c, and bsb_read.h. The bsb2raw.c is a simple converter from BSB to raw format. The bsbdataset.cpp code is a higher level wrapper of the low level code for use in GDAL.

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.tif

I 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.

Sample File

Sample files are available from a variety of locations. Check the NDI samples page.

Chart Sources

This is by no means authoritative, but the BSB nautical charts seem to be available from the following sources. Note that "modern" charts from MapTech seem to be encrypted in a manner not easily reversed, so charts bought from them can likely only be used with licensed MapTech software packages.