Museums have produced replicas of the real world for hundreds of years. Museums used to (and still do) cast dinosaur bones, or even an entire archaeological sites, using silicon rubber moulds filled with plaster and then painted. Unfortunately, this analogue process does not work for huge sites or intricate and fragile specimens. The traditional methods also introduce foreign materials and chemicals like silicon rubber, plasticine, latex and plaster into the specimens that are being replicated. However, digital 3D gets around all of this by using hands-off techniques to produce a digital replica. Museums are no longer bound by the realities of the physical world.
Our researchers use pixels, light, and lasers to capture the surface of sites, specimens and objects in a range of contexts, without needing to use any replication materials. These techniques include drone photogrammetry and LiDAR in the field through to micro-photogrammetry and light surface scanning in the lab. Each technique provides the museum with different abilities to capture the real world in virtual in detail never before thought possible.
Photogrammetry is not a new technology, but digital photogrammetry is and has revolutionised the 3D capture of the real world. Using hundreds to thousands of individual overlapping 2D digital photographs, captured from around a site, object or specimen, software can turn millions of two-dimensional pixels into three-dimensional points in space (a photogram model). This software process extracts the 3D pixels and produces a 3D ‘point cloud’. The cloud of points reflects the ghostly shape of the real subject captured in the photos. The more points you have the more detailed your cloud becomes, and the better your final 3D model. The software then creates a surface between these 3D points, turning what looked like a dust cloud into a solid object! These models can be used for all sorts of research, animation, display and even 3D printing.
Drone (UAV) photogrammetry
Fossil sites in Queensland are often very remote and can be difficult to access. Or sometimes, these sites might be under threat loss. Each time you excavate a fossil site you change it forever. So our scientists capture these sites before they dig, “digitise before you dig!”. Drones, or unmanned aerial vehicles, fly around very large sites, from 10s of meters to 100s of meters in size, photographing the environment as it goes. These photos are stitched together to create a 3D model of the site before and after it has been excavated, producing a 3D model of the fossil site through time (4D). With all of this 3D data, anyone in the future can re-visit a site and see what it looked like before it was changed. In the future, 4D scans will be how we ‘time-travel’ back to places and things in the past to see what they looked like!
Back at the lab, our palaeontologists use super high definition macro-lens cameras to capture our smallest specimens, only millimetres in size. As the specimens rotate on a turntable, they are captured in 3D, and using the same process of photogrammetry, models of each specimen are produced in micron accuracy. Tiny fossils need to be looked at under a microscope but they are exceptionally fragile and even the slightest bump could break them. Each time a scientist moves the specimen to study them, they risk damage to an irreplaceable specimen. High resolution 3D models of these tiniest specimens reduces the need to handle our precious specimens, assisting with their long term preservation.
Structured Light surface scanning
Much of a museum’s collection is dedicated to ‘Type Specimens’. Type Specimens are the most important representatives of any extinct or living species in existence and need to be preserved and conserved in perpetuity (over hundreds of years). However, scientists need to be able to see these specimens for their research. In the past, specimens may have risked being lost through postage or risked damage by trying to replicate them. Instead, high resolution surface scans can provide these researchers with enough detail to allow them to compare their specimens against others around the globe. We use micron-resolution structured-light surface scanning to help produce these models in an automated way. Specimens are placed on a turntable that automatically moves and predicts which directions the specimen needs to be positioned to scan. Structured-light scanning works in tandem with colour photogrammetry to produce the best resolution for a researcher to study.