The Irish projection: ITM
Every survey on the Irish mainland should be delivered in Irish Transverse Mercator (ITM), EPSG:2157. ITM replaced the older Irish Grid (TM75, EPSG:29902) as the Ordnance Survey Ireland working projection from 2001 onwards and is the default for planning submissions, Transport Infrastructure Ireland projects, and anything that touches local authority data.
If your survey contractor delivers data in WGS84 geographic coordinates (EPSG:4326) or in British National Grid, that is a red flag. The data will need re-projection before your design team can use it, and re-projection introduces rounding error.
The vertical datum: Malin Head
Heights in Ireland reference Malin Head vertical datum. This is the zero point of Irish height measurement, established at the tide gauge in Malin Head, County Donegal.
Getting heights right from GNSS equipment means converting ellipsoidal heights (what the receiver measures) to orthometric heights (what a site engineer expects) through a geoid model. In Ireland, the current model is OSGM15. A survey-grade drone operator applies OSGM15 during processing so your LandXML or CAD surface is already in Malin Head heights.
Common mistake: calling “OSGM15” the datum. Malin Head is the datum. OSGM15 is the geoid model used to convert GNSS measurements to that datum.
Deliverable formats your team will actually use
Every drone survey should arrive with outputs in the formats your design stack already consumes. Here is the shortlist:
Orthomosaic
- GeoTIFF – georeferenced, compressed, opens in QGIS, ArcGIS, Civil 3D, and Revit with the AutoCAD Map toolset.
- PDF – for tender packs and progress reports where a client wants an image at a set scale.
Digital Terrain Model (DTM) and Digital Surface Model (DSM)
- GeoTIFF (float32) – raster format consumed by most GIS packages.
- ASCII XYZ – plain text grid, slow but universally readable.
- LandXML – the right format for Civil 3D surface import used in topographical surveys. Triangulated mesh ready for volume and grading work.
Point cloud
- LAS / LAZ (v1.4) – the standard output of a drone LiDAR survey, readable by Cloud Compare, Leica Cyclone, Autodesk ReCap, and Trimble Business Center. LAZ is compressed (around 10% of LAS).
- Classified (ground vs non-ground) point clouds save your team hours of manual filtering before they can extract a bare-earth surface.
Contour plans and cross sections
- DWG – native AutoCAD, specify interval (typical 0.25 m or 0.5 m for earthworks).
- DXF – for teams using Bricscad, MicroStation, or non-Autodesk CAD.
Check before you commission
Put these four questions in any drone survey tender:
- What coordinate system and vertical datum will the delivery be in? (Expected: ITM, Malin Head, OSGM15 geoid)
- What independent check points are held back from processing and reported in the residuals document?
- What formats are included in the standard deliverable package?
- Who signs off the residuals report against the tolerances in the specification?
Any operator that cannot answer all four without hesitation is not working to survey-grade standards. For the full equipment picture, see our guide to survey-grade drone equipment.
Free reference · ungated
Drone Survey Deliverables: Guide for Engineers
12-page reference covering every file format, coordinate systems, file size expectations, and Civil 3D + Revit import walkthroughs. Print it, share it, keep it on your desktop.