GSI Open Topographic Data Viewer Tutorial
What is the GSI Open Topographic Data Viewer?
The Open Topographic Data Viewer is Ireland’s gateway to free, high-quality LiDAR data. Hosted by Geological Survey Ireland (GSI), it aggregates elevation data from seven government organizations. All data is free to download under Creative Commons Attribution 4.0.
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2×2 km Tiles
Individual download tiles
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0.13m–2m Resolution
Multiple resolutions available
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DTM & DSM
GeoTIFF raster products
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Free CC BY 4.0
No registration required
Data Providers
The portal aggregates LiDAR data collected between 2006–2021 from multiple Irish government organizations:
Step-by-Step Download Guide
Follow these steps to download Irish LiDAR data
The GSI Open Topographic Data Viewer welcome screen with data provider logos
01
Access the Viewer
Navigate to the Open Topographic Data Viewer. When the welcome screen appears showing logos from all data providers, click “I agree” to accept the terms of use and proceed to the map interface.
No registration required — the data is freely accessible to everyone under the CC BY 4.0 license.
02
Navigate to Your Area
Use the map controls to find your area of interest:
- Search box: Enter an Eircode, address, or place name
- Zoom controls: Use +/- buttons or scroll wheel
- Pan: Click and drag the map
The map displays color-coded tile boundaries indicating which organization provided the data. Use the Legend button in the toolbar to see all layer color codes.
Overview of Ireland showing LiDAR coverage areas by provider
Zoomed view showing 2×2 km tile grid boundaries
03
Select a Tile
Click directly on a tile to view its attributes in a popup window. The popup displays:
- Data provider and owner organization
- Capture date and published date
- Resolution (pixel size in meters)
- RMS error (vertical accuracy)
- License information
- Download links for DTM and DSM files
Note: You can only download one tile at a time through the popup interface.
04
Download Your Data
In the popup window, click the download link for either:
- DTM (Digital Terrain Model): Bare earth elevation with buildings and vegetation removed — ideal for hydrology, archaeology
- DSM (Digital Surface Model): First-return elevation including buildings, trees, and features — ideal for urban planning, forestry
Files download as GeoTIFF rasters, typically 5–20 MB per tile depending on resolution.
Pro Tip: Use the Attribute Table at the bottom of the map to see all available tiles in a spreadsheet view with direct download URLs.
Tile popup showing metadata and download links for DTM/DSM
Technical Specifications
📐 Coordinate System
Irish Transverse Mercator (ITM) — EPSG:2157
All data uses the ITM coordinate system with the Malin Head Ordnance Datum for vertical reference (mean sea level 1960-1969).
📁 Resolution by Provider
- GSI: 1m
- DCHG/Discovery: 0.13m – 1m
- NYU: 1m (Dublin)
- TII / OPW: 2m
- Westmeath CC: 0.25m
Tips for Large Downloads
Processing Irish LiDAR in Lidarvisor
Once you’ve downloaded your GeoTIFF files, Lidarvisor makes it easy to visualize and analyze your Irish elevation data.
Frequently Asked Questions
Yes. All data on the Open Topographic Data Viewer is licensed under the Creative Commons Attribution 4.0 International license (CC BY 4.0). You can use it for any purpose—commercial or non-commercial—as long as you credit the data provider.
No, coverage is not nationwide. The data focuses on specific areas surveyed by each organization, primarily along:
- Coastal zones (OPW flood mapping)
- Transport corridors (TII)
- Archaeological and heritage sites (DCHG, Discovery Programme)
- Urban areas (NYU Dublin, GSI)
- Specific counties (Westmeath)
Use the map viewer to check coverage for your specific area of interest.
The portal was designed for individual tile downloads to manage server load. For bulk data access, consider contacting the data providers directly or checking if your organization qualifies for data sharing agreements.
All elevation values in the Irish LiDAR data reference the Malin Head Ordnance Datum, which is based on mean sea level recorded at the tide gauge in Malin Head, County Donegal, between 1960 and 1969. It was adopted as Ireland’s national vertical datum in 1970.
The Open Topographic Data Viewer only provides processed raster products (DTM/DSM). For raw point cloud data (LAS/LAZ format), you may need to contact the original data providers directly:
Additional Resources
🔗 Official Links
- data.gov.ie Dataset Page — Official metadata
- Geological Survey Ireland — Primary portal host
- CC BY 4.0 License — Full license terms
📺 Learning
- Video Tutorial — Download and create hillshade models
- GSI Viewer — Start exploring now
More Free LiDAR Data Tutorials
Explore our complete collection of free LiDAR data download tutorials: