Topographic & Coordinate Survey GPS RTK · Drone · LiDAR · Bathymetric, Nationwide

A topographic survey measures the elevation and shape of the terrain to produce a contour map for engineering and construction. A cadastral survey measures the boundaries and area of a land parcel according to the title deed, and is carried out by Department of Lands officers or private surveyors licensed under the Private Surveyors Act B.E. 2535 (1992). SPN does not carry out legal land boundary surveys, but if boundary markers are found on site, their positions can be shown on the topographic map as a design reference (this is not a boundary certification)

GPS RTK suits large open areas with clear satellite signals; it is fast, with ±1–3 cm accuracy. A Total Station suits urban sites or sites with obstructions such as buildings, trees or factories, with ±5 mm accuracy. In practice SPN often uses both together for the best result

It depends on the job. For cut & fill volumes, orthophotos and 3D models, a drone survey at ±3–5 cm is sufficient and much faster. For setting out or as-built work that needs centimetre or millimetre accuracy, GPS RTK or a Total Station is still required

A bathymetric survey measures water depth and the condition of the bed with an echo sounder (an underwater sound instrument). The output is a depth map and bed profiles, used to design bridges and piers, calculate dredging and analyse scour at bridge foundations

Delivered as the client requires: AutoCAD DWG/DXF, PDF maps, Shapefile (.shp) for GIS, orthophoto .tif, 3D point cloud .las/.laz, Excel coordinate reports and a full survey report. Coordinates referenced to WGS84 or Indian 1975 (UTM Zone 47N/48N) as the project specifies

A 1–10 rai site takes 1–2 days of fieldwork and 2–3 days of processing and mapping. Price depends on the survey method, resolution, distance and site complexity. Contact SPN for a free quotation within 24 hours

TM47 (UTM Zone 47N) is used west of longitude 102° E, which covers most of Thailand. TM48 (UTM Zone 48N) is used east of longitude 102°, e.g. most of the Northeast, Sa Kaeo, Chanthaburi and Trat. Both can reference the Indian 1975 Datum (Department of Lands work / older maps) or WGS84 (modern GNSS work). SPN can deliver results in the coordinate system and datum the client needs, including conversion between WGS84 and TM47/TM48

Yes, nationwide across Thailand. We have survey experience in flat terrain, mountains, riversides and coastlines, from projects in Bangkok, the metropolitan area, the Central and Eastern regions to provincial projects across the country. Contact us for a quotation that includes an estimate of travel costs

Yes. Commercial drone flights in Thailand require the pilot to be registered with CAAT (Civil Aviation Authority of Thailand) and the aircraft to be registered with the NBTC, plus additional permission when flying in controlled areas. The SPN team holds all required licences and coordinates site flight permits for clients

Photogrammetry builds point clouds and orthophotos from overlapping photos. It suits open areas, bare earth and work that needs true-colour imagery, at lower cost. LiDAR fires a laser to measure distance directly; some pulses pass through gaps in foliage to the ground, giving true ground levels in plantations, forest or dense vegetation, where photogrammetry usually captures only the tree canopy. Many projects use both methods together

Two surfaces are compared, e.g. existing ground vs design levels, or ground before vs after earthworks, using a TIN or grid model in software such as AutoCAD Civil 3D. This gives cut volume, fill volume and a cut/fill map. Accuracy depends on point density and the accuracy of both surfaces. The volumes are in-situ volumes as measured and do not include soil swell or shrinkage, which the designer must also consider

Yes. Levels are carried by levelling from a benchmark (BM) of the Royal Thai Survey Department or another relevant agency near the project to the project BM, or GNSS heights are converted with a geoid model, which is more convenient but less accurate than levelling. If no benchmark is within a reasonable distance, an assumed level (local datum) agreed with the designer can be used

Single-beam measures depth point by point along the boat's track. It suits canals, rivers, cross-section work and tight budgets. Multibeam sweeps a wide swath of sound to cover the full bed and produce a high-resolution model, suited to ports, navigation channels and inspection around bridge foundations. Side-scan sonar images the bed to find obstructions; it does not measure depth directly