BSB (Nautical Chart Raster Format)
Mar 7,2026

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Introduction

BSB (Nautical Chart Raster Format) is a raster data format primarily used for storing and distributing Raster Navigational Charts (RNC). Originally developed for chart distribution, it has now become one of the standard distribution formats for official raster navigational charts issued by hydrographic offices in various countries. The BSB format adds georeferencing information to scanned paper chart image data, enabling accurate position display on navigation support software. It is characterized by its design specifically tailored for maritime navigation applications.

File Structure

A BSF format dataset mainly consists of the following files and information elements:

.KAP file (Raster data body): The main file storing the navigational chart image itself. The image data is saved in a compressed format and contains internal georeferencing information.
Header information (inside KAP): Metadata such as image size, resolution, geodetic datum, projection method, and coordinate transformation parameters are described in text format.
Georeferencing parameters: Holds information that associates reference points (control points) on the image with latitude/longitude coordinates, enabling accurate position display.
Color palette information: Contains palette data defining the color coding specific to nautical charts (shallow water, navigation aids, danger areas, etc.).
Associated metadata files (optional): May separately manage information such as issuing agency, edition number, and update date.

Pros

Optimized for navigation purposes: Since it can maintain the same visual representation as paper charts issued by official hydrographic offices, it is a format with high consistency with traditional navigation practices.
Widely supported software: Supported by many marine navigation software and ECDIS compatible systems.
Lightweight compression structure: Can be distributed with relatively lightweight file sizes through efficient image compression.
Built-in georeferencing information: Because image and location information are integrated, no separate world file is required.
Reliability as official data: As it is used as officially issued data by hydrographic offices of various countries, it has high reliability from the perspective of navigation safety.

Cons

Low expandability due to raster data: Unlike vector charts (ENC), dynamic acquisition of attribute information and layer control are not possible.
Increased capacity at high resolution: As resolution increases, file size grows, which may affect display performance.
Low editability: Being image-based, it is unsuitable for individual editing of features or attribute updates.
Limited for GIS analysis purposes: Not suitable for spatial analysis or advanced geographic information processing; its main use is limited to display and navigation.
Update management required: When new editions are released, files must be replaced, making it unsuitable for real-time updates.

Application Scenario

BSB (Nautical Chart Raster Format) is mainly used in maritime navigation and coastal navigation support systems. As official raster navigational charts, they are used on a wide range of vessels from pleasure boats to commercial ships, and are suitable for accurately overlaying a vessel's own position on electronic chart display systems. They are also utilized in fields such as maritime education, port management, and coastal surveillance. A major feature is that they can maintain the visual representation of paper charts as-is, enabling digitalization while preserving continuity with traditional navigation practices.