Revolutionizing Preservation and Access: 3D insect models
3D models and images of insects are of immense value to taxonomic research, as they ensure the physical preservation of specimens while granting global accessibility.
In recent years, 3D digitization has become increasingly important offering a unique way to digitally preserve, document, and provide access to physical objects and artifacts reaching a wider audience than ever before. This marks a departure from traditional methods, where experts needed to physically handle these items or send them across countries or even continents, risking damage or loss and incurring high costs and time.
In contrast to real-life specimens, 3D digital representations can be easily shared with researchers worldwide, facilitating collaboration and allowing for in-depth investigation of shape, form, and texture in high quality.
Methods of Digitization
Various methods exist for digitizing natural history collections. For obtaining 3D data, photogrammetry* is considered the most versatile method for objects of different sizes and considered low cost. In recent years, innovative imaging technologies have emerged, greatly speeding up the capturing of intricate specimens like insects. The resulting 3D models enable accurate measurement of 1D, 2D and 3D features, including functionally relevant traits, as well as the measurement of volumes which is not achievable with physical specimens. This technology reaches its limits when confronted with fine hairs and extensively reflective surfaces.
A prime example: The Entomological Collection of ETH Zurich
The Entomological Collection of ETH Zurich boasts over 2 000 name-bearing insect type specimens and around 2 million insect specimens in total, primarily from Switzerland, Central Europe, and Northern Africa. Type specimens hold paramount importance for taxonomic research, serving as the foundation for naming and describing new species. They are intensively studied items within entomological collections.
Insect specimens are preserved in a temperature-regulated room at ETH Zurich. Image: © Pierre Kellenberger, ETH-Bibliothek
The Entomological Collection of ETH Zurich consists of more than 2 million specimens. Image: © Pierre Kellenberger, ETH-Bibliothek
Its current holdings include historic and modern collections of Swiss and Central European insect species, as well as significant collections of Lepidoptera, Hymenoptera, and Coleoptera from other parts of the world. Image: © Pierre Kellenberger, ETH-Bibliothek
A current priority for the ETH Zurich Entomological Collection is to provide enhanced online access to its resources, through the digitization of key sub-collections and modernization of the collection database, as well as the development of online educational resources. Image: © Pierre Kellenberger, ETH-Bibliothek
Creating digital representations safeguards the physical integrity of these specimens, while speeding up the work of taxonomists and providing access to specialists in remote locations, particularly outside Europe and North America. While a significant number of specimens originate from the Global South, the lack of adequate preservation facilities in those regions necessitates their transportation to the Western World. Given the considerable challenges associated with on-site inspections due to limited resources, digitalization serves as a valuable tool, enabling scientists from the Global South to access their own specimens, along with other collections, in a digital format. This technology empowers them to engage in scientific research using these precious materials.
Pioneering this digitalization effort is the Entomological Collection of ETH Zurich, which acquired a DISC3D scanner developed by SMALL WORLD VISION in 2021, and thus became the first Swiss institute to embark on 3D scanning of its insect type collection. The Entomological Collection of ETH Zurich aims to refine and further develop the existing DISC3D scanner procedures extending this technology's benefits to exciting new avenues such as education and public outreach involving 3D insect models. The Virtual Insect Collections project supported by SNF Agora is a first step in this direction.
How does it work?
The DISC3D scanner used by the Entomological Collection of ETH Zurich utilizes structure from motion (SfM) photogrammetry to create 3D models. Remarkably, this scanner is the only system that integrates multi-view imaging and extended depth of field imaging in an automated process. Multi-view imaging captures morphological features, colors, and texture, rendering them in the resulting 3D models. Since insect specimens are often small and suffer from shallow depth of field, multiple images are taken at varying focus points and combined to yield a final extended depth of field image that is fully in focus.
The DISC3D scanner is equipped with an industrial camera and a compact macro lens. This configuration offers advantages like full computer control of image acquisition and processing. A hemispherical lighting dome prevents overexposed highlights on shiny insect surfaces. The specimen is mounted on a two-axis gimbal that moves the specimen through predetermined positions, thus enabling a comprehensive view from virtually all angles. The motorized camera captures multiple images of each specimen position, resulting in around 400 stacked images. These images are processed by photogrammetric software to create a detailed 3D model with a colored texture map. The resulting 3D models, alongside the stacked images, camera settings, specimen positions, and lens configuration serve as a comprehensive database.
Photogrammetry: Technology that uses contactless measurement methods and evaluation procedures to determine the position and shape of an object from photographs. Photogrammetry aims to achieve an exact three-dimensional geometric reconstruction of the recorded object.