Raster Charts XL are derived from raster-based material obtained under licence from the UK, and other, Hydrographic Offices where land and other non-marine features have been removed. This provides familiarity for users who work with nautical charts and has the advantage of being able to combine it with any land mapping, or aerial imagery, of your choice. Raster Charts XL coverage is available depending on permissions granted by contributing nations worldwide.
Raster Charts XL provide an immediate image which is symbolised and ready to use and are available as individual charts for different geographic areas at discrete scale levels. No additional software is required as they can be opened in any image viewer. Non-marine areas are provided as transparent pixels to allow the inclusion and display of digital land mapping, such as from a National Mapping Agency, OpenStreetMap or Google Maps. The familiarity of the nautical chart for the marine area is retained.
Raster Charts XL are available in GIS compatible file formats (GeoTIFF) as individual charts and panels, or as a seamless data service from OceanWise and our Licensed Partners. Take a look at our demonstration site or download our sample data, including our Marine & Coastal Data Products User Guide, to try it for yourself.
Nautical charts created for navigational purposes are not created like land mapping with complete coverage at specific scale levels. Nautical charts are created to provide navigators with enough information to navigate safely from A to B e.g. between ports. This means that larger scale charts are available in certain areas only e.g. within ports and port approaches, and that other coastal areas may not be covered to the same largest scale. The same is true farther offshore, where only medium and small scale charts are usually available. In addition, individual charts may overlap with other charts of a similar, as well as different, scale level, and that the scale of each chart is set depending on the real world geographic area that they need to cover.
In order to create the best user experience as possible for Raster Charts XL, we have used our knowledge and expertise, and feedback from users, to carefully select and define appropriate viewing scales for each individual chart when served in the WMTS. This ensures there is no ‘bleed through’ from smaller scale charts and the viewing scales are set to ensure the charts are legible e.g. do not become pixelated when over-zoomed.
If you have any questions or require further information on any of the above, or find an area where you believe charts should be visible and they are not, then please contact the OceanWise Support Team. We welcome your feedback.