Thermographic survey and mapping

SAL Engineering designs and produces integrated systems for thermographic surveys aimed at mapping the surface temperature of terrains and any other surface. The system consists of a remotely piloted aerial vehicle, with a stabilized flight attitude and planned by waypoints thanks to a ground control station, and a thermal camera with a bolometric sensor. Despite the miniaturization of the sensors, the sensitivity of the sensor allows obtaining high precision thermal measurements.

We produce thermal targets (TT K100 series) in order to identify the reference points and georeference the model following a GNSS survey in which the detected points are recognized in the images or in the thermal video. It is possible to obtain real-time images of the area investigated on the screen of the Ground Control Station, this allows to more carefully investigate the areas with thermal anolithiases.

 

Thermographic surveys are a major advantage in scenarios where it is necessary to investigate physical phenomena that influence ground temperature. For example, these aerial surveys are useful for agricultural land, fields, slopes subject to instability due to hydrogeological instability, urbanized areas, quarries, landfills and forests.

In archeology, the thermographic survey offers the advantage of being able to identify buried structures without the need for excavation, thanks to the difference in temperature of the structures themselves with respect to the surrounding terrain.

In the geophysical field the thermographic survey allows to create thermal maps of the survey areas with very high precision. For environmental monitoring it is possible to identify the leakage of pollutants into fields, lakes or rivers or near landfills. In emergency operations, it is possible to fly over areas at risk of fire without any danger to the pilot or to identify people or objects in dangerous situations.

 

The products generated by these surveys are geo-referenced thermal videos with the possibility of being connected to a geodatabase, high resolution thermal photos, thermal orthophotos and vector products for the areas where anomalies are found, such as isotherms and the digital model of the surface temperature. Inside the thermal orthophoto there is the temperature information for every single pixel, that is for every single part of the surface investigated.

 

The thermographic survey can be carried out in most environmental situations, it is not invasive and the data acquired are of rapid processing. The aerial survey is coupled with a GNSS survey on the ground, which allows geo-referencing the 3D model obtained and all the technical products required. Data processing is carried out using specific software and the creation of the 3D model takes place through a photogrammetric process, using the structure from motion and bundle adjustment algorithms, after generating the thermal images starting from the recording matrix of absolute temperatures in ASCII format. The thermal images, therefore, do not change the representation scale during the flight path, because a representation scale of the images is set with a grayscale proportion between the highest and lowest temperature recorded in the general scene, and not for each individual image, how the thermal imaging cameras' palettes work to "color" the video in real-time.