Guides, industry commentary and technical articles from the Angell Surveys team — covering UAV survey, LiDAR, inspection, BIM and the regulations that govern them.
Photogrammetry models the top of the canopy. Multi-return LiDAR records ground returns through gaps in it, so a bare-earth model under hedgerow, woodland and scrub is possible, but only as good as the canopy, the season, the point density and the classification allow.
LiDAR and photogrammetry reach the same RICS bands on hard detail. The choice is decided by the ground: vegetation, texture, light, structures and corridor geometry. A ground-by-ground guide to specifying the right capture method, or both.
Orthomosaic, point cloud, DTM and DSM, contours, CAD, the accuracy report and the datum statement: what each item in a UAV survey deliverable pack is for, what a client should look for in it, and the RICS band language it should be written in.
A drone LiDAR topographical survey is normally specified to RICS Band D or Band E and its accuracy is proven by independent check points, not by the sensor brochure. This guide explains the bands, what governs the achieved accuracy, and what the accuracy report must show.
A good UAV survey brief states the extent, the purpose, the datum, the RICS accuracy band, the deliverables and formats, the resolution, existing control, access and dates, site constraints and the reporting cycle. It does not specify the aircraft. Here is the ten-point list with example wording.
A drone measures position in a global GNSS frame. UK engineering wants OSGB36 National Grid and Ordnance Datum Newlyn. OSTN15 and OSGM15 are the Ordnance Survey models that make the conversion correctly, and a site grid is a further step on many infrastructure schemes. This guide explains each, with the OS accuracy figures.
What a UAV LiDAR survey of an overhead line corridor or a live substation actually delivers: a classified point cloud with the conductors in their own class, sag and clearance geometry, vegetation heights against the line, and a measurable 3D model of the compound, drawn from work we have delivered.
How a weekly UAV earthworks monitoring programme is built so that every epoch is comparable: permanent control, check points re-observed each week, identical flight design, surface differencing against the design TIN, zone-by-zone cut and fill, stockpile volumes and a 24-hour report that carries its own accuracy evidence.
PAS 128:2022 classifies every buried service on a utility survey drawing by how it was located: records (QL-D), site reconnaissance (QL-C), geophysical detection (QL-B4 to QL-B1) or exposure (QL-A). This guide explains the sub-levels, the methodology types, the RICS band each maps to, and how to choose the level for each project stage.
UK SORA has replaced the Operating Safety Case as the route to complex and BVLOS drone operations. After nine years under an OSC, Angell Surveys transitions to SORA in March 2027 — here is what the framework involves and how it underpins our BVLOS roadmap.
How a GNSS position in latitude and longitude becomes an Ordnance Survey National Grid coordinate — datums, ellipsoids, the Helmert transformation, OSTN15 and the Transverse Mercator projection, set out in full.
Surveying is the oldest applied mathematics there is. The geometry that measures a field in Suffolk is the geometry that measures one in Shaanxi — and that universality is what lets a global profession speak with one voice.