2026-04-12 · 6 min read
SVY21 is Singapore's national plane-coordinate system. EPSG code 3414. If your drone-mapping output, your surveyor's CAD file or your GIS layer ever drifts a few hundred metres on a Singapore site map — odds are someone forgot SVY21.
What SVY21 actually is
SVY21 is a transverse-Mercator projection on the WGS84 ellipsoid, with a fixed origin near the centre of Singapore and northing / easting coordinates in metres. The acronym stands for Singapore Vertical Datum and Survey 2021 — a refresh of the older SVY79 / WGS84-based working coordinates Singapore engineers used through the 1990s and 2000s.
Concretely: every point on Singapore land has a pair of metric coordinates relative to a single origin near Stamford Road. Cadastre, building plans, BCA / URA submissions and the SLA national mapping all use SVY21. If your drone deliverable is going to consume any of those inputs — or feed any of those workflows — your photogrammetry project must be on SVY21.
Why a national grid?
Two reasons. First, latitude-longitude is a curved-surface measurement; civil engineers want metres, not degrees. Second, every country with serious cadastre has its own grid for the same reason — Malaysia has Kertau RSO, Indonesia has TM3, Australia has MGA. The grid is calibrated to minimise distortion across the national footprint, which means lengths and angles read off the map are usable directly for engineering.
SVY21 in PIX4D, AutoCAD and ArcGIS
- PIX4D — pick "EPSG:3414 SVY21" from the project coordinate-system dropdown before processing. PIX4Dmatic, PIX4Dmapper and PIX4Dsurvey all carry it.
- AutoCAD / Civil 3D — load the SVY21 grid from the Geospatial coordinate-system library. Project location service must be enabled.
- ArcGIS / QGIS — set the data frame coordinate system to EPSG:3414. Reproject layers as needed; never combine SVY21 layers with WGS84 layers without an explicit transform.
- Global Mapper — handles SVY21 natively; the format-translation step is where you re-grid imported WGS84 KML or DWG layers into SVY21.
- Emlid Reach in Emlid Flow — set the coordinate system to SVY21 in the project preset. Easepect ships Reach receivers pre-configured.
SiReNT and SVY21
The SiReNT NTRIP service — the Singapore Land Authority's national CORS network — broadcasts corrections in WGS84. The receiver applies the SVY21 transform locally. Your RTK rover gives you SVY21 metric coordinates that are directly comparable with cadastral and engineering drawings.
Common mistakes
- Mixing SVY21 with WGS84 lat-long. They are not interchangeable. A WGS84 KML dropped onto an SVY21 dwg will land hundreds of metres off.
- Using SVY21 outside Singapore. The grid is calibrated for the Singapore footprint only. Cross the strait into Johor and you need Kertau RSO.
- Wrong vertical datum. SVY21 horizontal does not carry a height datum automatically — make sure project elevations reference the right vertical (typically Singapore Height Datum / SHD).
- Drone EXIF in WGS84. DJI flight logs write lat-long in WGS84. The photogrammetry step must reproject — every modern PIX4D project does this automatically once you set the output to SVY21.
When does SVY21 matter most?
Any time the deliverable will be consumed by, or compared to, a cadastral / BCA / URA / SLA / utility-authority record — which is almost every commercial Singapore engineering project. If the deliverable is a one-off internal visualisation that never leaves the consultancy, SVY21 is technically optional. The moment it leaves the building, it has to be on SVY21.
Easepect handles this for you
Every PIX4D licence, every Emlid Reach receiver and every drone-services engagement we ship is pre-configured for SVY21 plus the right vertical reference. Most operator drift in our experience comes from the next step downstream — a CAD or GIS file imported with the wrong default — and we walk customer teams through that during onboarding.