Engineering Survey Services — Cadreatech
UAV & Drone Survey Services in Kenya
Aerial photogrammetry for large sites, difficult terrain, rapid area coverage, construction progress monitoring, and stockpile measurement across Kenya. Orthomosaic imagery, Digital Elevation Models, Digital Surface Models, and 3D point clouds — processed at 3–5cm resolution into engineering-ready deliverables. KCAA-compliant operations with licensed pilots.
Understanding the service
What Is a UAV Drone Survey?
A UAV (Unmanned Aerial Vehicle) or drone survey uses a drone fitted with a high-resolution RGB camera — or in specialist applications, a LiDAR scanner — to capture aerial data over a site. The drone flies a pre-programmed autonomous grid pattern at a set altitude, typically 80–120m above ground level (AGL), capturing overlapping photographs at every position in the flight plan.
Each photograph is tagged with its GPS coordinate at the moment of capture. The complete set of overlapping images is then processed using photogrammetry software — typically Pix4D, Agisoft Metashape, or DroneDeploy — which applies Structure from Motion (SfM) algorithms to reconstruct the scene in three dimensions from the overlapping image set. The result is a dense 3D point cloud, from which orthomosaic maps, Digital Surface Models, Digital Elevation Models, and contour plans are derived.
Engineering-grade accuracy is achieved by establishing Ground Control Points (GCPs) on the ground before the flight using RTK GNSS receivers. Each GCP is a clearly visible target whose exact real-world coordinate is measured by the RTK receiver. When the photogrammetry software processes the imagery, it uses the GCP coordinates to anchor the 3D model to real-world coordinates — producing a georeferenced survey product rather than a floating relative model.
Why drone survey has transformed construction site management in Kenya
The adoption of drone survey in Kenya's construction and infrastructure sectors has accelerated significantly since 2018 — driven by falling equipment costs, improved software, and the recognition that aerial data provides capabilities that simply did not exist at any price before.
The orthomosaic alone has changed how large projects are managed. A monthly drone flight over a 20-hectare estate development provides the project manager with a true-colour aerial photograph accurate to 3–5cm — showing every structure, every stockpile, every area of cleared ground, and every construction front simultaneously. Site progress reports that previously required a full day of walking the site can now be produced from the office using the orthomosaic as a base.
For volumetric measurement — stockpiles, cut-and-fill verification, basement excavation progress — drone survey achieves results that are both faster and more accurate than traditional ground methods on large areas. A stockpile that would take a surveyor two hours to measure by total station can be captured by drone in 15 minutes and processed to a higher point density.
KCAA regulations for drone survey in Kenya
Kenya's Civil Aviation Authority (KCAA) gazetted the Remotely Piloted Aircraft Systems (RPAS) Regulations 2020, which govern all drone operations in Kenya. Key requirements include:
- Drone pilots must hold a KCAA Remote Pilot Licence (RPL) for the class of aircraft being operated
- Operations within 5km of a licensed aerodrome require prior permission from the relevant Air Traffic Service unit
- Operations over congested areas (defined as built-up areas with people) require KCAA operational approval
- Maximum operating altitude of 400ft (120m) AGL without ATC permission
- Drones above 0.25kg must be registered with KCAA
Cadreatech works exclusively with KCAA-licensed operators and obtains all required permissions before every survey flight. Our flight reports document the licence number, flight approvals, and airspace compliance for every engagement.
Drone survey vs. satellite imagery — why they are not the same
Clients sometimes ask whether Google Earth or commercial satellite imagery can substitute for drone survey. The answer is no, for engineering applications, and the reasons are fundamental.
Commercial satellite imagery of Kenya is typically captured at 30cm–50cm resolution — 6 to 15 times coarser than drone survey at 3–5cm GSD. More critically, the imagery may be months or years old — useless for current ground conditions. And satellite imagery is not planimetrically accurate to the standard required for engineering measurement — buildings lean, ground features are displaced, and measurement from satellite imagery introduces significant errors.
Drone survey provides current-date, 3–5cm resolution, geometrically corrected imagery tied to known ground coordinates. For any application involving measurement, design, or formal documentation, only drone survey meets the accuracy standard.
When drone survey is the right choice
- Sites larger than 3–5 hectares where ground survey would take multiple days
- Steep slopes, ravines, riparian zones, or areas with poor ground access
- Construction progress monitoring — monthly or milestone snapshot surveys
- Volumetric stockpile measurement on quarries, fill sites, and material yards
- Large estate or subdivision development requiring full site coverage quickly
- Road or pipeline feasibility over difficult terrain — rapid corridor data capture
- Environmental baseline surveys for NEMA EIA
- Flood zone and riparian area mapping
- Before and after surveys for earthworks volume verification
- 3D visualisation for client, investor, or planning presentations
- Mine or quarry face mapping and safety inspection
Typical drone survey coverage
| Platform | Area/day | GSD at 100m |
|---|---|---|
| Multi-rotor drone | 50–100 ha | 2.8–4cm |
| Fixed-wing drone | 200–500 ha | 3–6cm at 150m |
| LiDAR drone | 50–150 ha | ±5cm point accuracy |
Coverage rates depend on terrain, overlap settings, wind conditions, and battery capacity. LiDAR penetrates tree canopy for ground-level returns.
Drone vs traditional ground survey
UAV Survey vs. Ground Survey — Which Is Right for Your Project?
Both methods have important strengths. The right choice depends on your site size, terrain, vegetation, required features, and timeline. On many projects, a combination of both methods gives the best result.
🎯 Ground Survey — Best for:
- Small to medium sites under 2–3 hectares
- Urban sites with dense buildings obstructing aerial view
- Sites under dense tree canopy where ground levels are needed below vegetation
- Capturing underground features — manholes, invert levels, utility depths
- Setting out, as-built verification, and precision level work
- Situations where KCAA airspace restrictions prevent flying
- When the client needs instrument-measured specific spot levels
🚁 Drone Survey — Best for:
- Large sites above 3 hectares requiring rapid comprehensive coverage
- Difficult terrain — steep slopes, rivers, inaccessible areas
- Sites where photographic context is as important as survey data
- Construction progress monitoring across a whole site simultaneously
- Stockpile volume measurement on open material yards
- Clients who need a current aerial photograph of the site as a project record
- Large estate and infrastructure corridor surveys at feasibility stage
Deliverables
Drone Survey Deliverables from Cadreatech
All products are processed from raw drone imagery using photogrammetry software and issued in engineering-standard formats with a signed accuracy report.
01
Orthomosaic Map (GeoTIFF / PDF)
Geometrically corrected aerial photograph in true colour — planimetrically accurate to 3–5cm GSD, suitable for feature mapping, design overlay, and client presentation
02
Digital Surface Model (DSM)
3D surface model including all above-ground features — buildings, trees, structures. Used for visualisation, solar analysis, line-of-sight studies, and obstruction mapping
03
Digital Elevation Model (DEM)
Bare-earth terrain model with above-ground features removed — used for drainage analysis, slope mapping, contour generation, and civil engineering design calculations
04
3D Point Cloud (LAS / LAZ)
Dense 3D point dataset — for detailed feature extraction, volume calculation, structural modelling, and import into Civil 3D, Revit, or GIS platforms
05
Contour Plan (DWG / PDF)
Contour lines generated from the DEM at client-specified intervals — for topographic mapping, grading design, drainage planning, and county planning submissions
06
Volume Report
Earthwork volume calculations from surface comparison between two drone survey epochs, or between the drone surface and a design surface — for stockpile inventory or earthworks verification
07
Accuracy Report (PDF)
GCP residuals, independent checkpoint errors, and accuracy statistics confirming the survey meets the required engineering precision standard — signed by the survey team
08
KCAA Flight Compliance Report
Documentation of pilot licence, flight approvals, altitude, overlap, GSD, date, weather conditions, and KCAA compliance confirmation for project records
Step by step
Our Drone Survey Process
Site Assessment & Airspace Check
Review site size, terrain, vegetation, proximity to Nairobi airports (JKIA, Wilson, Embakasi) and any restricted zones requiring KCAA notification or special approval
KCAA Compliance
Obtain required KCAA flight approvals and ATC notifications for operations in controlled airspace or near aerodromes — typically 5–10 working days lead time for formal approvals
GCP Establishment
Ground Control Points marked and measured with RTK GNSS across the site — minimum 5 GCPs for small sites, distributed at corners and centre, with additional points for larger or irregular areas
Flight Planning
Autonomous flight path programmed — overlap set at 75–80% front and 70–75% side for photogrammetric reliability. Altitude selected to achieve target GSD.
Drone Flight
KCAA-licensed pilot supervises autonomous flight. Camera triggers automatically at planned positions. Ground observer monitors site safety during flight operations.
Image Processing
Imagery processed in photogrammetry software — alignment, dense cloud generation, mesh, DSM, DEM, and orthomosaic extracted and tied to GCP coordinates
QA & Accuracy Check
GCP residuals and independent checkpoint errors verified against required accuracy standard. Point cloud and DEM checked for gaps, artefacts, and processing errors before issue.
Deliverable Issue
Orthomosaic, DEM, DSM, point cloud, contour plan, volume report, accuracy report, and KCAA compliance documentation issued in client-specified formats
Frequently asked questions
Drone Survey Questions — Kenya
Can drone survey be done near Nairobi's airports?
Yes, but with additional procedures. Nairobi has several licensed aerodromes — Jomo Kenyatta International Airport (JKIA), Wilson Airport, Eastleigh Air Base, and smaller strips. Operations within 5km of these require coordination with the relevant Air Traffic Service unit and, in some cases, formal KCAA approval that includes operating procedures and safety mitigations.
We handle all airspace coordination as part of our drone survey service. For sites in Nairobi's CBD, Westlands, Industrial Area, and the eastern suburbs close to Wilson and JKIA, we build KCAA notification time into the project timeline — typically 5–10 working days for standard notifications and up to 21 days for formal approval applications.
How many Ground Control Points do you need for engineering-grade accuracy?
The minimum for engineering-grade accuracy is 5 GCPs — one at each corner of the survey area and one in the centre. This configuration achieves ±5cm horizontal and ±8cm vertical accuracy with standard overlap settings. For elongated sites, corridors, or irregular shapes, we distribute GCPs to achieve coverage throughout the survey area rather than concentrating them in corners.
For sites larger than 20 hectares, we add GCPs at approximately 300–500m spacing across the interior of the site. The additional GCPs improve internal accuracy and reduce the risk of systematic errors that can develop over large areas when GCPs are sparse.
We always include independent checkpoints — points measured by RTK GNSS but not used in the photogrammetry processing — to provide an unbiased accuracy assessment of the final deliverables.
Can you do drone surveys under tree canopy in Kenya's forested areas?
Standard RGB photogrammetry captures the surface of the tree canopy rather than the ground beneath — so in forested areas, the DEM represents the top of the trees, not the terrain. For applications where ground elevation under dense vegetation is required, two approaches are used:
- LiDAR drone survey — LiDAR sensors emit laser pulses that can penetrate gaps in the canopy and return ground-level reflections. Processing the LiDAR point cloud separates ground returns from vegetation returns, producing a true bare-earth DEM. This is the most accurate approach for forested terrain.
- Hybrid approach — drone survey covers the open areas while targeted ground survey (RTK GNSS or total station) is used in the forested zones. The two datasets are merged in Civil 3D to produce a seamless terrain model.
We advise on the appropriate approach based on vegetation density and the required accuracy of the ground model at scoping stage.
Can drone survey be used for construction progress monitoring?
Yes — this is one of the highest-value applications of drone survey on large construction projects in Kenya. A monthly or milestone-based drone survey of the project site produces:
- A current orthomosaic showing every active construction area — for programme monitoring and client reporting
- A current DEM for comparison against the previous survey epoch — quantifying earthworks volumes placed or removed in the period
- Point cloud data for 3D progress visualisation
- Documented photographic record of site conditions at the survey date — for contract records and dispute avoidance
For clients with ongoing programmes, we offer survey programme agreements covering multiple visits at agreed intervals — providing consistent data for programme tracking, payment certification, and project closeout documentation.
Related services
Services That Work With Drone Survey
Request a Drone Survey Quote
Tell us your site location, approximate size in hectares, and what the drone survey is needed for — topographic mapping, progress monitoring, stockpile measurement, or NEMA EIA baseline. We will confirm KCAA airspace requirements, advise on GCP numbers, and provide a detailed quotation within 48 hours.
