- Distributed ARCS charts are encrypted HCRF (hydrographic chart raster format) files, and not viewable on a GIS system.
- Distributed AVCS charts are encrypted (S-63) ENC (electronic navigational chart) S-57 files, and not viewable on a GIS system.
However - Both ARCS (when as GEOTIFF) and ENC (when as UNencrypted S57) are viewable within a GIS system.
- GEOTIFF does not require any specialist GIS tool to view and is regarded as a standard raster data format containing cartographic information (LONG/LAT, Projection)
- GEOTIFF are spatially reference raster-format images that are human-viewable but are limited by the amount of information available so best support imagery analysis function.
- GEOTIFF, as a raster format, retains the symbology and presentation as constructed. A GEOTIFF looks like a chart (without marginalia).
If the user wants to be able to extrapolate contours and other specific information, then this will require spatial analysis and image manipulation in GIS system.
- S57 may require specialist tool to view.
- S57 is NOT regarded as a standard GIS data format, but GDAL supports it so GIS software like ESRI’s ArcPro and QGIS, etc. can view .000 files.
- S57 is a vector file format and therefore the user can interrogate individual features such as contours and extrapolate specific information.
- As S57 is vector format, it will require a separate symbology file so as to replicate an ENC (electronic nautical chart) in appearance. UKHO does not supply this, but these files are available for free online (we’re unable to recommend supplier).
The UKHO does not license encrypted ARCS (HCRF) or AVCS (ENC) files/products – these are available through Admiralty Distributor channel - details available on Admiralty.co.uk/how-to-buy
If a customer wishes to use Admiralty/UKHO products as unencrypted geotiffs or S57 ENCs, then this will need licensing (Introduction to Copyright Licensing (ukho.gov.uk) for additional support and guidance.
