Construction and Use of Active Thermal Markers

Thermal monitoring of complex topographic objects requires accurate integration of infrared data with three-dimensional spatial information. However, registering thermal imagery with point clouds remains challenging due to limited spatial resolution, low contrast, and the lack of stable reference features in thermal images. This study presents a methodology for generating a thermal point cloud using active thermal markers as control points. The developed markers are based on temperature-controlled Peltier modules, providing stable and detectable thermal signatures independent of the natural temperature distribution of the investigated surface. Laboratory and field experiments evaluate marker stability, detection capability, and applicability for integration with Terrestrial Laser Scanning (TLS). An automated procedure was developed to identify thermal markers and transfer temperature information from infrared images to point clouds using a Direct Linear Transformation approach. The proposed workflow was tested on a coal spoil tip, where a combined spatially referenced model was made. The results confirmed that active thermal markers enable reliable thermal image registration and allow temperature values to be assigned to three-dimensional terrain models. The proposed approach can support monitoring of mining areas, detection of potential zones of heat accumulation, and early identification of areas at risk of spontaneous combustion.