In 2002, the museum established the Arius3D Imaging Centre at the museum’s research and collections facility for digitizing specimens for research, conservation and education. In a series of texts, I am bringing you behind the scenes to explain how we go from a specimen to a 3D model and, finally, to a complete 3D animation!
In 3D modelling, it all starts with the scan. Is it hard work? No. I just set the scanner’s travel points to move across the specimen and hit the start button. The scanner records as it moves along, creating a new scan with each pass.
For me, putting together all the individual scans afterwards to create a 3D model is a fun task. It’s like putting together a virtual 3D puzzle.
Here is a look at the scanner that I use in creating stunning 3D archival models of museum specimens. The table I’m standing beside is called a Coordinated Measuring Machine (CMM). It weighs 3000 lb (1360 kg). That’s extremely heavy! It’s perfect for putting large specimens on and not having to worry about the table swaying or moving when the scanner is moving.
The CMM also uses air to lift up the posts that hold the scanner. It’s like a giant air-hockey table! As a result, the scanner glides across the table without any resistance, thereby allowing for perfect scans.
The scanner scans both the surface geometry and colour of the specimen. This information is captured from the reflection of the laser that sweeps over the specimen’s surface as the scanner travels back and forth. The laser is white.
What’s cool is that the white laser is made up of three individual lasers: red (R), green (G) and blue (B). When the laser beams are combined together in a fibre-optic cable, they make white. Mirrors in the camera separate the three laser wavelengths and record the surface-colour values R, G and B for each point on the specimen.
Does the laser damage the specimen? No: the laser power is very small. It’s the equivalent of a hand-held laser penlight. Even so, you still don’t look into the scanner because a direct laser beam can harm your eyes, just like you would not shine a penlight into your eyes.
Unfortunately, not everything can be scanned. I can’t really scan my hand, for example. Our skin absorbs the laser light, so it doesn’t reflect back enough light to give information about the surface geometry. In this case, I could make a plaster cast of my hand and scan that, or simply coat my hand in baby powder.
An opposite case also means that some objects can’t be scanned: very shiny minerals and wet specimens reflect the laser light, thereby scattering it and not reflecting it back to the scanner. The scanner captures best those specimens that have a hard, matte surface, which can reflect the laser light back into the scanner.
What does a system like this cost? Well, it’s more than the price of a car, but less than the price of a house. The CMM table comes in a variety of sizes, from small tabletop versions to tables that a car can drive on.