Building Custom Drones (For DroneTM)¶

Sometimes it may not be possible to buy a drone off the shelf that is easily compatible with DroneTM.

A good example of this would be for thermal imagery projects.

In these cases, it may be preferable to assemble a custom drone using standard quadcopter components.

Overview¶

Component	Role
Pixhawk	Flight controller (e.g. autopilot)
QGroundControl	Ground control software used to plan/send missions
DroneTM	Generates the mission plan
Companion Computer (SBC)	Captures + geotags images

The end result is an autonomous quadcopter running PX4/MAVLink. Missions are generated in DroneTM, uploaded via QGroundControl, and flown autonomously - no manual piloting needed. A companion computer captures geotagged images at each waypoint using a fixed camera mount for nadir (straight-down) and/or 45° oblique shots.

This guide covers two build tiers. Both produce orthomosaics usable for building mapping (e.g. digitising an informal settlement). The high-end tier matches DJI Mini 4 Pro image quality. See the Component List for specific parts and prices.

Two Tiers¶

Tier	What you get	Est. total USD
Budget	Usable ortho for building footprint mapping. Some limitations - see below.	~$400–500
High-end	DJI Mini 4 Pro equivalent image quality on a custom platform. Same workflow as any consumer mapping drone.	~$900–1,200

Georeferencing and Accuracy¶

The onboard GPS geotags every image with a position accurate to roughly 2–6 metres. For building mapping, that is usually enough: you get a correctly stitched ortho that may be offset from true position by a few metres, but buildings are the right shape and size relative to each other.

If the ortho needs to line up precisely with existing map data, you can shift it to match known features (roads, intersections, existing building outlines). Vertical accuracy can be corrected in post-processing using reference surfaces.

Ground Control Points (GCPs) - surveyed markers placed on the ground before flying - will improve absolute positioning to tens of centimetres. They are useful but not essential for building mapping. If you have access to a GPS and the time to set up markers, use them. If not, the ortho is still usable - you may just need to offset it.

Hardware¶

A custom quadcopter requires the following categories of hardware. See the Component List below for specific parts and prices.

Airframe + propulsion: a 450–500 mm quadcopter frame with 4 brushless motors, 4 ESCs (electronic speed controllers), propellers, and a power distribution board (often integrated into the frame).

Power: a 4S LiPo battery and a balance charger. Buy at least two batteries for field use.

Flight control: a Pixhawk-class autopilot running PX4 or ArduPilot firmware, a GPS + compass module, and a telemetry radio (433 or 915 MHz depending on region) for the MAVLink link between the drone and your ground station laptop.

Avoid unbranded Pixhawk 2.4.8 clones

The cheapest Pixhawk boards (~$25 on AliExpress) are unbranded clones with well-known reliability problems: sensor failures, compass errors, and firmware issues. Spend the extra $10–20 on a branded board. For budget builds, use a Radiolink Pixhawk (~$35–50). For high-end, use a Holybro Pixhawk 6C Mini (~$131) or 6C (~$166).

Imagery capture: a camera module connected to a companion computer (Raspberry Pi) which captures, geotags, and stores images. A single camera pointed straight down (nadir) is the minimum. Adding a second camera at 45° captures building facades and features hidden from above.

Storage: a MicroSD card for the Pixhawk (flight logs) and one for the companion computer (captured imagery).

Optional: an RC transmitter + receiver for manual override. Recommended as a safety measure.

Important

Be sure you are taking any restrictions from your aviation authority into account when planning the build.

The drone must be registered to be flown. If in doubt, clarify with them first.

Assembly¶

Mount motors to frame
Wire ESCs to flight controller
Connect GPS + telemetry
Install battery system
Balance all propellers (see below)
Mount camera underneath on vibration-isolated bracket (see below)
Connect camera to companion computer
Secure all wiring and verify no loose components

Vibration Management¶

This is critical for mapping

Commercial mapping drones like the DJI Mini 4 Pro have a gimbal that absorbs vibration. This build has no gimbal. If vibration from the motors reaches the camera, you get "jello" distortion - wobbly, warped images that are unusable for mapping. There is no software fix for badly jello-affected images. Getting vibration right is not optional.

There are two things to get right: reduce vibration at source and isolate the camera from what remains.

1. Balance every propeller before flight.

Unbalanced propellers are the single biggest source of vibration on a quadcopter. Cheap nylon props (1045s) are often significantly out of balance from the factory.

Use a magnetic propeller balancer (~$5–15). Place the prop on the balancer, see which side dips, and add small pieces of tape to the light blade (or carefully sand the heavy blade) until it sits level. This takes 2–3 minutes per prop. Do it for every prop, every time you fit new ones.

2. Isolate the camera from the frame.

The camera mount must be mechanically decoupled from the frame using soft rubber. Two proven approaches:

Rubber ball dampers (also called "gimbal dampers") - small rubber balls with screw studs at each end. Mount 4 of these between the frame and a camera plate. These are widely available (~$3–5 for a set of 4, search "anti-vibration rubber ball damper drone" on AliExpress). This is the recommended approach.

Silicone grommets or O-rings - thread bolts through silicone grommets to mount the camera plate. Cheaper but harder to tune.

The goal is that if you tap the frame, the camera plate should wobble gently on its mounts rather than transmitting a sharp vibration. If it feels rigid, the isolation is not working.

3. Also soft-mount the flight controller.

The Pixhawk has its own IMU sensors that are affected by vibration. Use the foam pads included with the Pixhawk (or a dedicated anti-vibration mounting plate, ~$3) to isolate the flight controller from the frame. High vibration readings in the Pixhawk logs (visible in QGroundControl) indicate a problem.

4. Check for jello on a test flight.

Before flying a mapping mission, do a short test hover and capture a few images. Look at them on a screen. If straight lines (rooftops, roads) appear wavy or wobbly, you have a jello problem. Fix it before flying a real mission - the images will be unusable.

Common fixes if jello persists:

Re-balance propellers (they may have been damaged)
Check for loose motor screws or bent motor shafts
Try softer damper balls on the camera mount
Replace cheap propellers with better quality ones (still 1045 size, but from a reputable brand)

Software¶

Install Firmware (MAVLink Enabled)¶

Flash PX4 onto the Pixhawk and configure: frame type (quadcopter), GPS, failsafes, telemetry link, and radio control (if using).

PX4 or ArduPilot? Both are open-source, both use MAVLink, and both work with QGroundControl. For autonomous waypoint missions they are functionally interchangeable. This guide references PX4 as the default since it is the native firmware for Pixhawk hardware, but ArduPilot is a drop-in replacement if preferred.

Connect Controller¶

Connect the Pixhawk to a device running QGroundControl (your laptop / device 'base station'). QGroundControl sends MAVLink instructions to the PX4 flight controller.

Generate Flightplans In DroneTM¶

DroneTM generates QGroundControl-compatible flightplans. These are imported into QGroundControl and sent as MAVLink instructions to the onboard controller.

May 2026 Component List¶

Both tiers share the same airframe. The difference is the flight controller and camera setup.

Airframe (common to both tiers)¶

#	Component	Recommended	Backup	Est. USD
1	Frame	S500 500 mm PCB + landing gear	F450 450 mm (less payload room)	$15–30
2	Motors ×4	A2212 920KV brushless	Any 2212/2216 800–1000KV	$12–25
3	ESCs ×4	30A SimonK or BLHeli	Any 30A brushless ESC w/ 5V BEC	$10–22
4	Propellers	1045 nylon CW+CCW (buy 3+ spare sets)	9450 props	$3–6
5	GPS	u-blox NEO-M8N + compass on mast	BN-880 or M10 GPS/compass	$10–22
6	Telemetry radio	SiK V3 - 433 MHz (EU/Africa) or 915 MHz (Americas)	Any 3DR-compatible telemetry pair	$15–35
7	Battery ×2	4S 14.8V 5200 mAh 35C+ LiPo (XT60)	Any 4S 3300–5200 mAh LiPo	$50–90
8	Charger	IMAX B6 balance charger (or clone)	Any LiPo balance charger supporting 4S	$12–25
9	Storage	2× MicroSD (8 GB for Pixhawk, 32–64 GB for SBC)	Any Class 10 MicroSD	$8–15
10	Camera mount	3D-printed fixed bracket on rubber ball dampers (nadir + optional 45°)	Aluminium L-bracket on silicone grommets	$5–15
11	Prop balancer	Magnetic propeller balancer	Any prop balancer	$5–15
12	Wiring & sundries	XT60 connectors, zip ties, foam tape, heat shrink, battery strap	-	$10–20
	Airframe subtotal (excl. flight controller)			~$155–310

Budget Build¶

Component	Recommended	Est. USD
Flight controller	Radiolink Pixhawk 2.4.8 (branded)	$35–50
Companion computer	Raspberry Pi Zero 2 W	$15
Camera	Raspberry Pi HQ Camera (IMX477) + 6 mm low-distortion CS lens	$60–80
Budget camera + FC subtotal		~$110–145
Budget total (airframe + above)		~$400–500

Why the Pi HQ Camera and not the cheaper Pi Camera Module 3? The Pi Camera Module 3 (~$30) uses autofocus and a fixed lens with significant barrel distortion. Both hurt stitching accuracy. The Pi HQ Camera uses interchangeable lenses and manual focus - you fit a low-distortion 6 mm CS lens (~$10–20 on AliExpress, search "6 mm CS lens 5 MP low distortion"), lock focus to infinity, and get significantly better orthomosaic geometry. The lens is the most important part of the camera for mapping.

Budget tier: what to expect and how to get the best results

The Pi HQ Camera produces a usable 12 MP ortho at ~2.5 cm/px GSD (at 80 m altitude). Buildings are clearly identifiable and traceable. The main limitations vs. the high-end tier are:

Smaller sensor (1/2.3") means worse low-light performance. Fly in good daylight only.
Rolling shutter on a small sensor means you need to fly slowly (≤6 m/s) and keep shutter speed fast (≥1/1000s). Set exposure manually before each flight - do not use auto exposure.
No gimbal - the camera is fixed to the frame via vibration dampers. This is the biggest risk on the budget tier. Follow the Vibration Management steps carefully. If your propellers are unbalanced or your camera mount is too rigid, you will get jello distortion and the images will be unusable.
The flight controller (Radiolink Pixhawk) is adequate for autonomous waypoint missions but has less sensor redundancy than the Holybro boards. Test thoroughly before field deployment.

To mitigate these limitations:

Balance your propellers before every new set.
Test for jello on a short hover before each mapping mission.
Fly with ≥80% frontlap and ≥70% sidelap. More overlap compensates for any individual soft images.
Fly at ≤6 m/s. Slower is better.
Set exposure manually: shutter ≥1/1000s, ISO as low as lighting allows.
Process with OpenDroneMap and enable rolling shutter correction if available.
If the resulting ortho is offset from your base map, shift it to align with known features.

High-End Build¶

Component	Recommended	Est. USD
Flight controller	Holybro Pixhawk 6C Mini (or 6C)	$131–166
Companion computer	Raspberry Pi 5 1 GB (or Pi 4 2 GB)	$45
Camera	Arducam IMX586 48 MP USB3 + 6 mm low-distortion C-mount lens	$130–150
High-end camera + FC subtotal		~$310–360
High-end total (airframe + above)		~$900–1,200

The Arducam IMX586 uses the same 1/2.0" 48 MP quad-Bayer sensor technology found in consumer drones. In 12 MP binned mode it produces ~1.6 cm/px GSD at 80 m with good light gathering and fast readout.

Replace the stock lens

The Arducam ships with a motorised autofocus lens. Replace it with a fixed 6 mm low-distortion C-mount lens (~$20) and lock focus to infinity. Autofocus can shift during flight and the stock lens is not optimised for low distortion.

The Holybro Pixhawk 6C Mini has redundant IMUs, vibration isolation, temperature-controlled sensors, and active firmware support. It is a significant reliability upgrade over the budget Pixhawk.

The Pi 5 (1 GB, ~$45) provides USB 3.0 needed for full-speed 48 MP capture. The 1 GB model is sufficient - the SBC only needs to capture images and write them to SD.

High-end tier: what to expect

With the right lens and good daylight, this build produces orthomosaics comparable to a DJI Mini 4 Pro in resolution and stitching quality. The DJI has a slightly larger sensor (1/1.3" vs 1/2.0") and a factory-calibrated gimbal, so it has an edge in low light and consistency. In practice, for daytime building mapping the difference is small.

The one area where this build requires more care than a DJI is vibration management. The DJI's gimbal handles vibration automatically. On this build, you need balanced propellers and a properly isolated camera mount (see Vibration Management). Once that's done, follow the same flight practices as any consumer mapping drone: fly at ≤8 m/s, ≥80% frontlap, ≥70% sidelap, set exposure manually, and process with OpenDroneMap or similar.

Thermal Cameras¶

Thermal cameras connect via SPI to the companion computer and are the same for both tiers.

Option	Spec	Est. USD
FLIR Lepton 3.5 + breakout board	160×120, radiometric (calibrated temperature per pixel)	$200–320
FLIR Lepton FS + breakout board	160×120, non-radiometric (thermal image only)	$99–160

The 160×120 resolution is useful for spotting heat anomalies (roof insulation gaps, water leaks, solar panel defects) but is not high enough for detailed thermal orthomosaics. It is a scouting tool, not a mapping sensor. For mapping-grade thermal you need a 640×512 sensor (e.g. FLIR Boson, ~$2,000+) which is outside the scope of this build.

The Lepton 3.5 gives calibrated temperature data per pixel. The Lepton FS is cheaper but only produces a thermal image without temperature values.

Dual Camera Setup¶

For 3D reconstruction, mount two cameras - one nadir, one at 45°. Oblique shots capture building facades, roof overhangs, and features hidden from directly above.

On the budget tier (Pi Zero 2 W), use an Arducam multi-camera HAT (~$10) to switch between two CSI cameras. On the high-end tier (Pi 5), use one USB camera for nadir and one CSI camera at 45°.

Build Weight¶

Tier	Dry (no battery)	All-up
Budget	~1,000 g	~1,500 g
High-end	~1,100 g	~1,600 g

Both within the S500's max takeoff capacity (~2 kg+).

Telemetry Frequency by Region¶

Region	Frequency
Europe, UK, most of Africa	433 MHz
Americas (US, Colombia, etc.)	915 MHz
Australia, New Zealand	915 MHz

Sourcing¶

All airframe components are intentionally generic - the A2212 motor, 30A ESC, and S500/F450 frames are among the most widely cloned drone parts in the world.

For the flight controller, buy from the manufacturer or an authorised reseller (Holybro store, Radiolink store). Generic "Pixhawk" boards from random AliExpress sellers are often unreliable clones.

For countries with good e-commerce (Colombia, etc.), AliExpress ships to most of Latin America (2–6 weeks). MercadoLibre often stocks generic drone parts locally.

For countries with limited e-commerce (Sierra Leone, etc.):

Local RC / electronics importers in the capital - most stock generic drone parts. Ask for "F450 drone kit" or "Pixhawk".
Alibaba (wholesale, min 5–10 units) - ships worldwide via DHL/FedEx.
Pre-purchase and carry with staff - buy in the US/UK/EU and bring in luggage. Most practical for specialist parts (flight controller, cameras).
Freight forwarder (ColisExpat, MyUS) - provides a US/UK address and forwards packages internationally.

Retailer	Best for	Ships globally?
AliExpress	Frame, motors, ESCs, props, GPS, telemetry	Most countries (2–6 wks)
Alibaba	Bulk orders (5+ kits)	Worldwide via DHL/FedEx
Holybro Store	Pixhawk 6C / 6C Mini, power modules	Worldwide
Amazon US/UK	Batteries, chargers, Arducam cameras	Many countries; forwarder if needed
GroupGets	FLIR Lepton modules	US, UK, EU, AU, CH only
The Pi Hut / Pimoroni	Raspberry Pi boards, Pi Camera modules	UK/EU; intl. via forwarder
Arducam store	IMX586 USB3 camera, IMX477 boards	Worldwide

Warning

LiPo batteries cannot go in checked airline luggage. Carry-on rules vary by airline. Often easier to source batteries locally than to import them.

Thermal camera modules require an End Use Statement for international orders. GroupGets ships to US/UK/EU/AU/CH only. For other countries, buy in those regions and carry to the destination yourself.