Wall Inspection via DRONE

This blog is based on case sharing from DJI Enterprise.

When it comes to keeping buildings safe and looking their best, exterior wall inspection plays a huge role. Depending on the type of surface—painted walls with finishes like tile or paint, or unpainted walls such as concrete, masonry, glass curtain walls, or wood—the inspection approach can vary. Professionals rely on different techniques to spot hidden problems: visual inspections to catch obvious cracks or damage, infrared thermography to detect moisture or heat leaks, rope access for those hard-to-reach high-rise spots, and the classic tapping method to identify hollow or loose areas. By combining these methods, professionals can uncover issues early, prevent costly repairs, and extend the life of their exterior walls. It’s all about protecting both the structure and the people inside.

DRONE Hardware Accuracy Components

When capturing the most accurate and precise data possible from drones, a number of hardware components play a key role. DJI Matrice 4E/ DJI Matrice 4T and D RTK-3 Multifunctional stations are great options.

• Camera/sensor Quality

• Sensor size

• Shutter type

• Image time accuracy

• RTK Receiver(s) Quality

• Base Station Accuracy

• Distance of Drone to Base Station/Correction Source

• Use of Ground Control Points

Mission Capture Methods with DJI

Slope missions and geometric missions are automated flight route planning tools in DJI Pilot 2 app for capturing data for 3D reconstruction, with slope missions designed for angled surfaces like facades and roofs, and geometric missions for general 3D mapping of objects or land plots using polygonal or cylindrical boundaries. Both mission types involve using AR to define the mission area, adjust parameters, and then fly a predefined path with the drone. 

Please refer to below diagram for more features during a drone wall inspection.

Step by Step guide to fly a Slope Route

Pre-flight

Connect RTK，make sure RTK fixed. Open flight assistance camera view

Step 1 : Create a AR projection of captured area

•Use aircraft’s Wide camera, choose single photo mode

•Make sure the distance between drone and captured area is within 150m.

•Adjust camera towards to captured area, making sure camera view be parallel with captured area as much as possible.  Gimbal pitch is 0 degree

Press C1 to generate AR projection。

Step 2: Adjust AR projection setting

•Adjust AR projection covered area

•Adjust the distance, angles between AR projection and the actual captured area

•Select “Slide/Rotate Mapping area” to delete AR projection

Step 3: Adjust flight route setting and save

Such as GSD, distance between AR projection and actual captured area, flight speed, course angle, overlap ratio, route start point,etc

Step 4: Execute Mission

•It is recommend to fly in VLOS

•Make sure to successfully execute mission when obstacle avoidance turning-on

•Keep checking the flight assistant camera at the left bottom of camera view  to make sure fly safety.

•It is supported to adjust gimbal pitch during flight.

•Turning on AE locked to make the exposure consistence.

Always checking if the camera focus works well

Step by Step Guide to Geometric Route

1.Plan base surface

First, please select the shape of the bottom surface (polygonal prism or cylinder).

After selecting, click on the map to draw the bottom area.

2.Set the base and top height

Fly to the base and top of the object to be measured, and press C1 or C2 to set the current height of the aircraft as the base and top height.

Manual input of top/bottom height (ASL EGM96) is supported.

Tips:

–RTK is recommended for setting height using the drone.

–If you use GNSS for height setting, ensure a safe distance around (no obstacles within 10 meters).

–If you use manual input, ensure the ASL(EMG96) value is used. For more information, refer to the navigation display area.

Optimal Weather for drone infrared Survey

• Clear weather

• Dry exterior wall

• Wind speed below 5 m/s

• Relatively few reflections from surrounding buildings (which can affect surface temperature)

• Is it possible to shoot parallel to the exterior wall?

• Can shooting be done during even temperature?

Case Sharing

In 2022 in Japan, the Building Standards Act was revised to officially recognize the use of drone-mounted infrared cameras as an alternative to the sounding inspection method. This change allows for the extensive photographing of exterior walls using drones, with the images then being analyzed to create reports. While traditional methods could take over a month to complete, using drones can finish on-site inspections in just 1 to 2 days. Additionally, this method prevents the aesthetic loss caused by erecting scaffolding, which has been well-received.

Drone: DJI M350RTK+ DJI Zenmuse H30T

Mission planning: Pilot 2

Infrared Analysis Software:DJI Thermal Analysis Tool 3