Shom raster Geotiff digital nautical chart
Shom raster digital charts are in GeoTIFF format, with a resolution of 300 dpi. They are the digital image of paper nautical charts and meet the chart carriage requirements for pleasure craft under 24 meters in length. For other categories of vessels, they can only serve as a navigational aid.
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Shom raster Geotiff digital nautical chart
Shom raster digital charts are provided in GeoTIFF format, with a standard resolution of 300 dpi. They are produced from official paper nautical charts and faithfully reproduce their content, symbology, and layout. These charts are exact images of the paper nautical charts and comply with carriage requirements for pleasure craft under 24 meters in length. For other categories of vessels, they may only be used as a navigational aid.
Following your order, we will send you a download link via WeTransfer to the email address you provided.
You can view Raster and ENC S57 charts with software such as QGIS (Geographic Information System) and GlobalMapper (wave modeling). We have no information regarding ENC S63 compatibility. These software tools are designed for cartographic analysis, not for real-time navigation.
Format and technical specifications
- Format: GeoTIFF compliant with the TIFF 6.0 standard, with embedded georeferencing tags.
- Projection: Mercator or Lambert, depending on the source chart, with WGS84 (EPSG:4326) geodetic reference system or a specific local projection.
- Resolution: 300 dpi (approximately 0.085 mm/pixel on the original paper chart).
- Metadata: Embedded in the file (extent, georeferencing coordinates, projection system, scale).
- Average file size: Variable depending on paper chart format, typically between 50 and 200 MB per chart.
Software compatibility
The GeoTIFF format is supported by several navigation and GIS (Geographic Information System) software applications:
- Navigation software: OpenCPN, …
- GIS: QGIS, ArcGIS, MapInfo, Global Mapper…
- Other uses: Integration into cartographic visualization systems, overlay with vector layers (bathymetric data, AIS, weather, regulatory zones).
Usage and regulatory limitations
- Pleasure craft (< 24 m): Shom GeoTIFF raster charts are recognized as equivalent to paper charts and meet the carriage requirements under French regulations.
- Professional navigation (> 24 m): These charts are considered navigational aids only. Vessels subject to SOLAS regulations must use ENCs (Electronic Navigational Charts, S-57/S-101) on an approved ECDIS system.
- Updates: Unlike vector ENCs, GeoTIFF raster charts do not support incremental updates. Users must download new editions or corrected versions published by Shom.
Advantages and limitations
- Advantages: Wide software compatibility, identical readability to paper charts, easy integration into a GIS environment.
- Limitations: No native interactivity (no clickable objects, unlike ENCs), need to download new files for each update, regulatory restrictions for commercial navigation.