SeaZone Charted Raster

SeaZone Charted Raster is based on scanned and geocoded images of Admiralty Charts and is available for immediate use in Geographic Information Systems, without the need for additional software, add-ons or plug-ins, resulting in gains in time and performance.

Application

SeaZone Charted Raster data provides ideal backdrop mapping for a variety of applications on the desktop and Internet. The data can be combined with your own datasets to make the display and dissemination of maps within reports or over the Internet simple and effective.

Coordinate Reference System

Each Charted Raster has its own unique projection based on either Mercator or Transverse Mercator, but referenced to the Horizontal WGS84 Datum.

Supply Format

Charted Raster files are supplied as Geo-referenced GeoTIFFs with LCW compression as standard. These files are available for use once copied to the user's system. GIS Project files are not included with Charted Raster. They should display appropriately in most modern GIS systems e.g. ESRI ArcGIS 9.x, Cadcorp 6.1+.

Map Info requires the projection information to be setup prior to loading, please see the section below. For access to the data in other systems please contact us.

Historically, the primary source of bathymetry has been the nautical chart. However, as charts are designed to aid the safety of navigation they do not truly represent the real world. Overall water depths may be up to several metres shallower than in reality; this is known as shoal bias. Depth contours are generalised and simplified for easy reading, and in some instances missing and broken contours are apparent. Scant information is available in many areas, where there is little or no risk of grounding. This lack of detail makes charted bathymetry unsuitable for many applications, including environmental modelling and engineering design, where more accurate and detailed depth information is required.