T&A Survey | Drone projects

Detection of seepage locations in dikes with Infrared (IR) Thermography

For a regional water authority, T&A Drone Services has carried out Infrared (IR) themorgraphy measurements to identify potential seepage locations that may indicate weak spots in the dikes.

Thermal images

T&A performed the survey with a high resolution radiometric thermal camera on a multi-rotor drone. This camera create a thermogram, a visual representation of the prevailing temperatures on the measured object with different colors indicating variations in temperatures. Weak spots in dikes not yet visible to the eye can be easily recognized on IR thermography images.

Environmental conditions

Temperature differences at ground level are caused by differences in the moisture content of the substrate. For these differences to be as large as possible, they should be caused by seepage water and not by rain. A cloudy day without rain is therefore optimal for making good infrared measurements. Prior to and during the flight, environmental and weather conditions are constantly taken into account. If these parameters cannot be adjusted, measurement data recorded on different measurement days cannot be compared.

Mapping a channel with RPAS photogrammetry

In 2017 T&A Survey Drone Services performed a photogrammetric drone survey for the regional water authority Waterschap Drents Overijsselse Delta.

Survey goal

The goal of the drone survey was to map a secondary channel of the river Vecht by performing an photogrammetric revision analysis covering the entire area. The Waterschap constructed the secondary channel in 2015. A natural process will gradually change the course of the channel due to the development of a meander. The information obtained from the photogrammetric survey clearly shows the current position of the secondary channel, making it possible to closely monitor its future natural development.

SmartPlanes fixed-wing drone

Since the research area is about 2 km long, the Waterschap decided the best way to perform the survey was from the air. T&A Used the SmartPlanes Freya, a fixed-wing drone which is particularly suitable for the 3D mapping of large areas.

Photogrammetry

The more than 2.000 photo's that were taken during the survey have been processed with photogrammetric software into photographic images with XYZ-information. The scale, hight and color contrasts of the images have been corrected and processed into a point cloud. From this point cloud a Digital Elevation Model (DEM) and an orthophoto (below) were calculated.

Petrochemical site mapped with drone photgrammetry

drone onderzoek op petrochemisch terrein in Roemenie

For a client, T&A carried out a drone 3D Photogrammetry measurement of a petrochemical storage site in Romania. The area had to be mapped three-dimensionally for planned remediation activities. Given the large surface of the research area and the required data accuracy, the client wanted the measurements to be carried out by a drone.

Research area

The research area is located 60 kilometers north of the capital Bucharest and has a surface of 33 hectares. Above ground oil storage tanks and oil pools are spread over the site.

Results

The RPAS (drone) study consisted of two flights and resulted in point clouds, a Digital Elevation Model (DEM) and an Orthophoto. The total of 644 photo images were processed into a photo image with XYZ information using photogrammetric software. The photo image has been corrected for scale, height and color differences. The data is then processed into a point cloud. A Digital Elevation Model (DEM) and orthophoto have been calculated from this point cloud.

Reference list

Performed drone surveys

Client	Project goal
Belectric GmbH	3D Photogrammetric Survey of solar park near Kerkrade
Water authority Hollandse Delta	Dike inspection with IR Thermography
Tauw BV	3D Photogrammetric Survey petrochemical plant in Romania
Water authority Drents Overijsselse Delta	3D Photogrammetric Survey to map a riverbed
Province of Groningen	Crop monitoring with IR Spectrometry

Specialists in Soil Investigation

Drone Projects