MIDA - Marine Irish Digital Atlas

Topography

The following are suggested sources for geospatial data related to the topic:

Ordnance Survey Ireland: The OSI Discovery Series are topographic maps at a scale of 1:50,000. Digital versions are also available as scanned map rasters, vector contours or height data.

Ordnance Survey Northern Ireland: OSNI provides topographical data at a variety of scales in raster and vector formats.

The above organisations also supply DEMs at a ground spacing of 10m and 50m.

USGS SRTM DEM: The SRTM DEM, at a spatial resolution of 90m, may be downloaded free of charge from this site. Masking of water bodies, clipping to coastline and reprojection may have to be carried out.

SRTM DEM from ERA-Maptech: A fully masked and coastline-clipped DEM of Ireland, in Irish National Grid projection at 70m ground spacing, may be purchased from ERA-Maptec.

SRTM DEM Hillshade: A hillshaded version of the SRTM DEM of Ireland may be freely downloaded from this NASA site.

Vexcel DEM: A DEM of Ireland, which has a 50m ground spacing generated using a combination of radar stereoscopy and interferometric techniques, may be purchased from Vexcel.

LANDMAP DEM: This product, generated using SAR images from the ERS satellites, has a ground spacing of 30m, however it is not very good quality. It may be appropriate for generating hill shading or simple correction of satellite images, but it is not appropriate for detailed analysis. It is freely available to third level institutions which are part of the CHEST agreement.

GTOPO30 DEM: The United States Geological Survey provides a DEM for the whole globe with a ground spacing of 1km. It may be downloaded free of charge. It was created with data from a number of sources.

ACE-DEM: The ACE-DEM, which also has a 1km ground spacing, has corrected many of the errors in the GTOPO30 global DEM by incorporating information from the radar altimeters on board the ERS satellites.

As ASTER data is available at very low cost, it is possible to generate a DEM yourself cheaply. Specific image processing software is required. One such software comes from PCI Geomatics, although other companies may also offer appropriate solutions.