What a Drone Topographic Survey Gives You
A topographic survey records the shape of the ground and everything on it: levels, slopes, drains, kerbs, walls, trees and structures. On an open site, a drone captures that information in one short flight instead of days of walking with a GNSS rover or total station, and it records every square metre rather than a grid of spot heights.
From the photographs we produce a dense 3D point cloud of the site. That becomes the deliverables designers and contractors use:
- Contour plan — at the interval you specify, typically 0.5 m or 1.0 m, as DWG or DXF.
- Spot levels and features — levels on a grid and at key features, referenced to Singapore Height Datum (SHD).
- Digital terrain model — the bare ground surface, for drainage, platform and earthworks design.
- Orthophoto — a georeferenced, scale-correct aerial image of the whole site in SVY21.
- Classified point cloud — ground, noise and water separated, in LAS 1.4 format.
Singapore's Standard for Drone Surveys
In January 2023 the Singapore Land Authority published the Standard and Specifications for Survey Using Unmanned Aerial System in Singapore. It sets three survey orders, each with its own accuracy and point density, and says which jobs each order suits.
| SLA survey order | Accuracy (horizontal / vertical) | Minimum point density | Typical use |
|---|---|---|---|
| 1st order | 0.051 m / 0.026 m | 24 points per m² | Topographic plans for submission, pre-construction and as-built surveys, volume certification |
| 2nd order | 0.051 m / 0.051 m | 12 points per m² | Construction progress, earthworks, preliminary design |
| 3rd order | 0.102 m / 0.102 m | 4 points per m² | Feasibility and environmental studies, general terrain models |
Accuracies are absolute, at the 68% confidence level (RMSE, 1 sigma), as set out in Table 2-1 of SLA's January 2023 standard.
The standard also draws two clear lines. First, drone surveys are not suitable for cadastral or boundary work, which stays with a licensed cadastral surveyor. Second, the sensor matters: SLA's equipment table lists only LiDAR for 1st-order work, while photogrammetry suits 2nd-order work with a camera of at least 42 megapixels, and 3rd-order work with at least 24 megapixels.
We survey by photogrammetry with a 100-megapixel camera, so we scope most topographic jobs as 2nd or 3rd order. If your project needs 1st-order accuracy, we tell you at the quote stage, because that calls for a LiDAR survey.
When You Need a Registered Surveyor
Under SLA's standard, the survey report and survey plan are certified by a Registered Surveyor. If your topographic plan is going to a Qualified Person, a consultant or a government agency, it will usually need that certification.
We can work either way. If you already have a Registered Surveyor, we fly the capture to their brief and hand over the data, control and validation results for them to certify. If the survey is for your own use, such as earthworks planning or progress tracking, we deliver the processed outputs directly.
How We Fly a Topographic Survey
- Scope the order. We agree the survey order, contour interval, deliverables and whether the plan needs certification.
- Set out control. Ground control points are placed across the site, no more than 100 m apart for 2nd-order work, and coordinated from SLA's SiReNT network or ISN markers. At least 4 independent validation points are added for every 10 hectares.
- Plan the flight. We size the ground sample distance to better than one third of the accuracy required, with at least 60% forward and 50% side overlap, below 61 m (200 ft), under CAAS permits.
- Process. Images are processed into a point cloud and terrain model in SVY21 and SHD, then classified into ground, noise and water.
- Validate. The validation points are kept out of processing and used to check the result. Their residuals in X, Y and Z are reported against the survey order's tolerance.
- Deliver. Contours, levels, terrain model, orthophoto and point cloud, with the validation report.
Where Drone Topography Works Best, and Where It Doesn't
Works well
Open and cleared land, earthworks platforms, construction sites before and during works, slopes and drainage corridors, industrial yards and car parks.
Needs care
Freshly reclaimed sand and other uniform, low-contrast ground, and sites with sharp height changes such as tall buildings. SLA notes photogrammetry errors rise on these, so we add control points.
Not suitable
Ground under dense tree canopy, which a camera cannot see through, and any boundary or cadastral survey.
CAAS-Permitted Operations
Our flights run under the required CAAS operator and activity permits. We handle the airspace approvals, including near Changi, Paya Lebar and Seletar.
Topographic Survey Pricing
Prices cover planning, CAAS permits, ground control set-out, the flight and processing. Certification by a Registered Surveyor, where you need it, is quoted separately.
| Site area | Drone capture and processing |
|---|---|
| Under 1 hectare | $1,000 — $1,500 |
| 1 — 5 hectares | $1,500 — $3,000 |
| 5 — 20 hectares | $3,000 — $6,000 |
See also our drone site survey, cut and fill earthwork survey and photogrammetry and 3D mapping services.
Frequently Asked Questions
Get a Topographic Survey Quote
Send us the site address, approximate area, contour interval and whether the plan needs certification. We reply with a scope and quote within 24 hours.