In the Animal Simulation Laboratory at the University of Manchester in the UK, data from 3D scans of the skeletons of both pre-historic and modern-day animals is being used to create accurate 3D digital models. Dr Bill Sellers, programme director in zoology at the University, then uses the 3D models in the simulation of their gait using a specialised software program developed in-house at Manchester University called GaitSym.
Critical to the process of turning 3D scans into final computer simulations is Geomagic Studio, a 3D imaging and reverse engineering software that is used around the world to convert data captured in 3D scans of physical objects into accurate 3D digital models for use in a wide range of applications.
‘There are many instances when the only way to discover how or why some part of our physiology does what it does is to create a 3D virtual model and then simulate its movement,’ said Dr Sellers. ‘For example,’ he explained, ‘in biology the standard practice when you want to find out what something does tends to be to remove it and see what the effects are. But you can’t do that in reality. So by using the digital models and simulations that we produce, biological and physiological experiments can be performed without using live animals – or people.’
The data from a 3D scan of the skeleton, taken with a laser scanner, a CT (computed tomography) scanner or a LiDAR (light distance and ranging) scanner, is read into Geomagic Studio to produce an accurate 3D digital polygon surface model. This data is in the form of a point cloud or polygons, depending on the scanner. Within Geomagic Studio, the multiple scans required to capture the complete skeleton are registered with each other and merged to create a single 3D scan data model.
Once the unified scan data model has been created and cleaned-up as necessary, a one-button process in the software wraps a polygon surface around it to automatically convert it to a polygon surface model, which can be further edited. This editing might include filling in holes in the model caused by the scanner not being able to access parts of the skeleton that were obscured by other parts, or repairing the mesh where necessary to improve the model’s accuracy. The software’s Mesh Doctor tool automatically detects and corrects errors in the polygon mesh to yield higher-quality, surface-ready polygon models.
Once the final 3D polygon model of a complete skeleton has been created it is decimated to reduce the polygon count so that it can be imported successfully into Autodesk 3ds Max software for the next step in the process.
‘The Geomagic Studio model is as the skeleton was in the laboratory or in the museum where it would have had a “dramatic” pose,’ said Dr Sellers. ‘We want it to be standing straight with everything symmetrical, so we use Autodesk 3ds Max to repose it by moving individual elements around until it is the way we want it – a straightforward, anatomically accurate model.’
The reposed model is then imported into Manchester University’s own software for simulating gait, GaitSym.