Sensor selection and 3D data representation in virtual forests

Advances in 3D reconstruction techniques have recently democratized point cloud generation methods in various domains, including forestry and general tree mapping. This in turn has been driving the development of the virtual forest concept. Despite its potential, this concept remains only vaguely defined within the forestry domain, often varying in meaning depending on its implementation. Recognizing this ambiguity, our work seeks to unify the diverse interpretations of virtual forests by proposing a standardized definition from a geomatics perspective. Two main ambiguities may be identified in the literature: first, which sensor to use in which case during the data acquisition phase of virtual forests. Second, how to represent the data in the virtual world. In an attempt to bridge these gaps, we introduce two critical concepts: the sensor-oriented Level of Scale (LoS) and the data-centered Level of Detail (LoD). The LoS concept aims to help 3D technology users in choosing which sensor is best suited for their purposes by using the scale of the scene and its complexity as the determining factors. This presents a very useful tool during the project planning phase, where balance between data quality and project budget is an important aspect. The LoD concept on the other hand, draws inspiration from established definitions in CityGML to represent trees in different complexities. In this study, the proposed LoD also incorporates an additional dimension to account for variations in data formats (e.g., mesh, point clouds, parametric models, etc.). These frameworks aim to clarify and structure the representation of virtual forests, addressing inconsistencies in their application across different contexts. A numerical analysis was also conducted to further highlight the practical implications of these concepts in improving the precision and utility of 3D vegetation mapping techniques. Although the findings of this study do not aim to establish an official standard—achieving this would require further collaborative efforts across disciplines—they provide a foundational framework for advancing standardization efforts. By offering a structured approach to defining and representing virtual forests, we hope to contribute to the broader development of practical, scalable guidelines that can be applied within forestry and related fields. This initiative marks a step forward in aligning geomatics with the needs of modern forestry applications.