Tower of Pisa 3D-scanned in 20 mins with spring-mounted Zebedee
September 19, 2013
Researchers at Australia's national science agency, the CSIRO, have developed Zebedee, a spring-mounted 3D laser scanner and mapper capable of scanning complicated interiors in double-quick time. The researchers were able to scan the "cramped and complex" interior of the Leaning Tower of Pisa which, the CSIRO claims, has not been possible with previous 3D scanning technology. But more significantly, the researchers were able to complete the scan in under 20 minutes.
It's the spring that appears to be the key to the technology. To laser scan any 3D space of any complexity, you have to place your scanner at numerous locations in order to "see" around any obstructions that might be present. The spring allows the scanner to sway from side to side, helping the scanner to peak around detailed obstructions and capture small details from numerous viewpoints, continually capturing data as its carrier moves around the interior.
But the spring also poses problems. When computer software attempts to piece the data together, it's crucial that it knows the location of the scanner at the point of every scan in order to correctly stitch together the incomplete 3D snapshots into a whole model. How do you do that if the scanner is continually carried about, much less lolloping on the end of a spring?
According to the researchers, the device includes an inexpensive inertial sensor which provides "rough" tracking of the rotations of the spring. The team's specially-developed software combines these inertial measurements (along with, presumably, some additional positioning data) and the laser range scanning information to build a 3D point cloud of the space – and in less time than it took to conduct the survey.
It may sound as though this might amount to fuzzier, less accurate models than with traditional static laser scanners, but the researchers claim that this is not the case. "This technology is ideal for cultural heritage mapping, which is usually very time consuming and labour intensive. It can often take a whole research team a number of days or weeks to map a site with the accuracy and detail of what we can produce in a few hours," says Dr. Jonathan Roberts, who leads the program at the CSIRO. He claims that the Pisa model includes small details in the stairways and stonework.
The device is presumably named about the character of Zebedee, a springed jack-in-the-box in the 1960s children's television series The Magic Roundabout.