Capturing drone images
The quality of your measurement stands and falls with your drone images. With the right flight methodology and preparation, our test cases achieve accuracies of under 1 % deviation.
Which drone
Roofy does not need an expensive pro drone. What matters is not the model or the price, but three functions and correct GPS coordinates in every photo. We developed our guide with the DJI Mini 4 Pro and tested it with other DJI models for compatibility.
Your drone must meet these three requirements
POI (Point of Interest)
Automatic circular flight around a marked object. The standard method for clean shots from all directions.
Cruise Control (Tempomat)
Automatically maintains constant speed and direction. Important for long buildings such as warehouses where POI does not work.
GPS in the photo data
Every photo carries the exact position as invisible information. Without these coordinates, Roofy cannot calculate the roof.
We calibrated Roofy with the DJI Mini 4 Pro. All altitude, distance and angle values in this guide refer to this model. With other DJI drones the values may differ slightly, but the result remains comparable.
Compatible DJI models (selection)
DJI Mini 4 Pro
249 g, under the Swiss 250 g threshold. No BAZL registration required. Our reference model. More than enough for single-family and medium multi-family homes.
DJI Mini 3 Pro
249 g, also under 250 g. Similar sensor quality to the Mini 4 Pro. No side obstacle sensor, so fly a bit more carefully.
DJI Mavic 3
895 g, BAZL registration required. Larger sensor and higher image quality. Worth it if you regularly capture larger objects.
DJI Air 3
720 g, also BAZL registration required. Has two lenses including a medium telephoto. This lets you keep more distance from the building while still seeing detail. Practical for large multi-family homes or dense areas where you cannot fly close.
Other manufacturers
Roofy is tested on DJI drones. Drones from other manufacturers (for example Autel, Parrot, Skydio) can in principle work as long as they meet the three points above. We have not, however, tested them systematically and cannot guarantee image quality or measurement accuracy.
If you want to use a non-DJI drone, check before you buy:
- Does the drone write GPS coordinates into the EXIF data of every photo? This is the most important requirement.
- Is there a function comparable to POI: automatic circular flight around a marked object?
- Is there a function comparable to Cruise Control: constant speed on straight stretches?
- Can you smoothly trigger the shutter manually during the POI flight (about every 2 seconds)?
- Does the drone produce JPEG photos at a minimum of 12 megapixel resolution?
If you successfully use a drone from another manufacturer with Roofy, we would love your feedback. Reach out via the feedback button so we can add other models to this list.
Pre-flight checklist
Run through these four points before every flight.
Pre-flight checklist
Drone battery 100% + spare battery on hand
At least one full spare battery is enough for most single-family home shoots.
Wait for GPS lock before takeoff
Wait until the DJI app shows the GPS lock (green status). Without GPS lock there is no correct EXIF data. Images are rejected by the upload.
SD card: enough space
Not necessarily empty, but room for 30-100 JPEGs (~5-10 GB).
Weather fits the flight
Overcast day or morning/late afternoon in sun. No rain, no fog, wind below 8 m/s. Details in the weather section further down.
Drone flight methodology
Two flight methods cover virtually all building types. POI is the standard for single-family homes, Cruise Control is for long buildings such as warehouses.
Method 1. POI (Point of Interest)
Standard for orbit flight around the building. Works for most single-family homes and compact multi-family homes.
What POI does
POI is an automatic function on the DJI drone. You mark an object on the screen and the drone flies a circle around it on its own, always with the camera pointed at the marked object. You keep distance and altitude constant and only press the shutter during the flight.
- Altitude
- 20-30 m above the roof (reference from the first nadir, hold ±5 m)
- Horizontal distance
- 20-30 m from the facade
- Gimbal (camera angle)
- −45° tilted down
- Rotation speed
- Slow to medium. A full orbit should take about 60-90 seconds
Altitude is a reference, not a fixed value. The first nadir image sets your flight altitude — from then on hold that altitude ±5 m for the entire orbit. Important: always measured above the roof, not above the ground. For an 8 m tall house this means about 28-38 m measured from the ground.
Step by step
- Launch the drone and climb above the centre of the roof until the whole house with some margin is visible in a nadir image (gimbal -90°). Take 2-3 photos. This altitude is your reference for the rest of the flight.
- Move the drone sideways to 20-30 m horizontal distance from the facade. Keep the altitude (reference from the first nadir). Tilt the gimbal from -90° to -45°.
- On the live view of the display, draw a square around the roof area (drag a frame with your finger). This tells the drone what the target object is.
- Activate tracking, then tap POI in the lower menu. The drone confirms acquisition and positions itself automatically.
- Pick a rotation direction (clockwise or counterclockwise, either works) and set speed to low or medium. Tap Start. The drone begins the orbit.
- During the flight press the shutter manually every 2 seconds. At normal speed this yields 30-50 photos per orbit and 70-80 % overlap.
- After one full orbit, stop the drone in place and quickly check the shots. Fly a second orbit if needed.
Even an angle below 45° works as long as the roof edge stays visible on every side. But the angle should not become too shallow either, otherwise the drone sees more facade than roof. The roof must clearly be in the frame.
If the roof edge does not fit in the frame: do not adjust the gimbal, reposition the drone instead. Either fly further away so the whole roof fits in the frame, or climb higher with a steeper angle. Then fly another orbit. This way POI does not have to continuously correct the angle during the flight and the shots come out more uniform.
Method 2. Cruise Control (Tempomat)
For long buildings such as warehouses, schools or row houses where POI does not work.
Why POI is not enough here
POI flies a circle. For a 60 m long building, the circle radius would be about 40 m and the drone would be far away from the roof. Per-image resolution would be too poor for a good measurement. With Cruise Control you instead fly parallel to the building at short range and the same level of detail is preserved.
- Button assignment
- Assign C1 or C2 to Cruise Control (DJI Fly app → Settings → Controls)
- Altitude
- 20-30 m above the roof (reference from the first nadir, hold ±5 m)
- Horizontal distance
- 20-30 m from the nearer facade
- Gimbal
- −45° tilted down
- Speed
- Slow, about 2-3 m/s. That leaves enough time for sufficient photos per pass
Step by step
- Before the flight, assign a custom button (C1 or C2 on the controller) to the Cruise Control function in the DJI Fly app.
- Launch the drone and climb above the centre of the building. At an altitude that gives a good level of detail on the roof (rule of thumb: 20-30 m above the roof). Tilt the gimbal to -90° and take several overlapping nadir shots along the long axis. For very large or long buildings, prefer more overlapping nadirs at 20-30 m over flying higher. This altitude is your reference for the rest.
- Move the drone sideways to one end of the building: 20-30 m horizontal distance from the nearer facade. Keep the altitude the same. Tilt the gimbal from -90° to -45°.
- Start flying parallel to the facade at a constant speed of about 2-3 m/s. Keep altitude and distance visually constant.
- Once the flight path is stable, press the assigned C1 or C2 button. The drone now keeps speed and direction constant on its own. Your hands are free for the shutter.
- Press the shutter every 2 seconds until you reach the end of the building. For a 50 m long warehouse this gives about 20-30 photos per pass.
- Cruise Control off, turn the drone and reposition for the next pass. For long buildings, fly back and forth twice for full coverage.
For long buildings, the centre of the roof, the nearer roof edge with facade and the corners must remain visible. The further part of the roof may be cut off. What matters is that the near side is fully in the frame.
Best workflow for evenly sided houses
This routine has proven itself for single-family homes and compact multi-family homes. It delivers consistent shots and avoids the most common mistakes. Follow the steps in order.
- Launch the drone and position it above the centre of the roof. Climb vertically until the whole house with some margin is visible in a nadir image (camera 90° straight down). This altitude is your reference for the entire flight. Rule of thumb: use the same altitude (±5 m) for the later orbit too.
- Keep this altitude from now on. This is critical. If you fly lower or higher in between and take additional nadir images, double images appear in the aerial view when the images are stitched. Roofy can no longer calculate the roof cleanly.
- Tilt the gimbal to −45° and start POI. Mark the centre of the roof on the screen and activate POI. The drone automatically keeps distance from the object. Watch the angle. If POI tries to readjust too much and the angle becomes too shallow, cancel, choose a better starting point (see Method 1 above) and start over.
- Fly one full orbit around the house. During the POI flight, press the shutter manually every few seconds. Rule of thumb: roughly every 2 seconds at normal POI speed yields 70-80 % overlap. For a typical single-family home, 30 to 50 photos are enough for one full orbit.
- Check before landing. Take a quick look at the photos on the screen. Are all roof corners visible? Is exposure even? When in doubt, fly another orbit right away rather than having to come back later.
Nadir shots: the essentials in brief
- The first nadir defines the flight altitude for the entire flight. Climb until the whole house is fully visible in one image.
- Hold the same altitude from then on (±5 m) for the orbit images.
- Do not take or upload nadir images from different altitudes. Sort them out at the latest during the upload. In our tests this caused double images in the aerial view (ghosting).
- For very large or long buildings: take several overlapping nadir shots from 20-30 m instead of flying higher.
- Camera angle: gimbal at -90° straight down.
Number of images
Scales with building size. These ranges reliably cover our test cases:
- Single-family home30-50 images
- Multi-family home50-80 images
- Warehouse / large flat roof80+ images (typically 60-100 on Cruise Control flights)
Weather and time of day
Pragmatic. Roofy works in most weather, but some conditions are clearly better than others.
Optimal
Overcast day. Diffuse light, no hard shadows or reflections
OK
Sunny day in the morning or late afternoon. Soft shadows
Difficult
Midday sun. Hard cast shadows can affect the result
Wind
Below 8 m/s for stable shots
No-go
Rain, snow, fog
What to watch out for
These conditions can affect the result, but in most of our test cases it still worked. Pay attention to warnings in the tool and verify with the elevation map (shortcut H) that the entire roof surface has correct elevation data.
A warning does not necessarily mean an error. It is an indicator that should be verified with the elevation map.
Possible interference factors
- Scaffolding around the building
- Vegetation right next to the roof (trees that reach the roof)
- Reflective surfaces (solar panels, glass windows)
- Hard midday shadows
Concrete pitfalls from the field
Avoid altitude changes on nadir images
Do NOT take nadir images from different altitudes. This causes double images in the aerial view. Set the altitude once and keep it.
Stay close to the roof
The closer to the roof, the better. Do not show much surroundings. The rest of the image is irrelevant for the reconstruction.
Example flight plan
Orbit flight with eight camera positions and nadir images from constant altitude. The pattern described in the POI method as a diagram.
Legal
Drone flying in Switzerland is subject to BAZL regulations (registration from 250 g, insurance, no-fly zones). Details in the FAQ.
For a 3D model with facades (Pro) you need extra orbit shots around the building. The 3D Capture: Facades guide.
Next step
On to the 3D capture
For a 3D model with facades, take extra orbit images — or skip straight to uploading.