Marine Digimap is accompanied by detailed help pages to aid you through the varying facilities. There are also quick guides to the facilities available in the Getting Started section. The help pages also contain detailed information about the datasets used in the service and available for download; a glossary is also available.
The data publication dates page is kept up to date with information on when the datasets in Marine Digimap were last updated.
No, the data in these maps is not sufficiently comprehensive or up to date to be used for offshore navigation.
Important: At no point is the data ever up-to-date enough to be used for navigation. Maps and data from Marine Digimap should NEVER be used for navigation under any circumstances. Further information is available.
These are maps rather than charts because they are not for navigational purposes. Typically only maps for navigational purposes such as for ships or for aircraft are termed 'charts' (e.g. Hydrographic Charts, Aeronautical Charts etc.).
There are several reasons why your Raster Charts might not georeference properly. Raster Charts are delivered in GeoTiff format, which is explained fully in the Data Formats section. If you are having problems with the GeoTiffs you may need to download the latest service pack or patch for your GIS software. This is a known issue for ArcGIS 9.0 and 9.1.
If you have edited the GeoTiff files in a graphics package to add new features or labels, it is likely that the georeferencing information will have been lost. You will need to download the data from Marine Digimap again if this is the case; most GIS packages will allow you to add graphics to the maps without losing the georeferencing information. We would recommend you add such data within the GIS application rather than the graphics application.
The source data is in WGS 84 but we display the data in British National Grid (OSGB36 datum, Airy Spheroid), both on screen and in printed maps.
Although we have used the same source dataset for all zoom levels, we have made a selection of features to display at different scales so as not to overcrowd or clutter the display.
Try resetting the feature selection back to the Basemap using the "Reset to Basemap" button in the Map Content Control.
The text is not horizontal because we are storing the raw data in the database in its native coordinate system which is Geographic (Lat/Long) WGS 84. To display (and print) this data in British National Grid (which is what we are doing in Marine Roam) we need to transform the coordinates from one coordinate system to another. In this process the text locating point is being transformed but the orientation (which was horizontal) is also being transformed so that it is rotated slightly. This is more noticeable the farther you are away from the Central Meridian of the British National Grid coordinate system (i.e. 2° West).
The Get Feature Info interface will return a list of all features that exist in the database for the point you have selected (plus a small buffer around it). To see all features that exist at the point you have selected you can turn them all on using the Select/De-Select all layers toggle in the Map Content Control menu.
This is because the source dataset (Marine Themes Vector) has been compiled mainly from the largest scale UKHO Hydrographic Charts available for a particular area. Hydrographic Charts are highly variable in terms of scale, coverage and date of update. They are also not edgematched so that features on one chart may not match features on another adjoining chart (even if they are the same scale). Consequently, for many features in the Marine Themes Vector dataset there are discontinuities, gaps, missing areas etc. at these data boundaries.
As well as being compiled from data shown on Hydrographic Charts, the data supplier has used other sources of information for specific feature types in the Marine Themes Vector dataset. For Wrecks that includes the source UKHO wrecks database which includes wrecks that are not charted. The accuracy of position on many of these non-charted wrecks is sometimes not sufficient to accurately locate them. It should also be noted however that some wrecks are on land either because they have been deliberately sunk or are in areas where the coastline has changed location.
Not found what you are looking for? Please ask a question or give feedback by emailing (digimap@ed.ac.uk) or chatting with the Digimap team.
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