A Backpack for BIM
Students aren’t the only ones taking an interest in new backpacks this fall. A LiDAR backpack developed by researchers at the University of California at Berkeley is drawing increased attention as a quick and affordable way to generate 3D building information models (BIM).
Pioneered by Avideh Zakhor, a professor and lead researcher in the university’s video and image processing lab, the backpack system was first introduced in 2009 as a way to map the interiors of multistory buildings. Since then, the device has been tested in a wide range of applications and substantially improved to streamline data collection, increase accuracy, enhance robustness and reduce its weight and size.
“We’re continually making configuration changes to the system to improve design and performance,” Zakhor says.
The current iteration of the backpack, which weighs 60 pounds, consists of five miniature lasers and two cameras that simultaneously capture data and images as the wearer walks at a normal pace through hallways, up and down stairwells, and in and out of rooms. Proprietary software generates point clouds from the collected data, which can then be used to automatically generate 2D floor plans or textured 3D models that can be viewed interactively. Using the backpack system, entire buildings have been mapped in as little as eight hours.
Although the accuracy of the system is lower than what can be achieved with static scanning, Zakhor doesn’t see that as a limitation. “It’s not centimeter-level accuracy, but there are many applications where you don’t need that level of accuracy,” she says.
One big potential market is in capturing information for energy simulation packages. “In addition to 3D geometry, three main parameters are considered in the energy simulation packages for buildings: lighting conditions, sources of loads (computers, printers, monitors, etc.), and windows,” Zakhor says. “If those parameters can be automatically detected and the semantic information extracted from a point cloud, then you can reduce the cost of generating that data manually. With the LiDAR point cloud together with the imagery captured by the backpack system, we can do that.”
Zakhor notes that with the simple addition of an infrared camera, the system can also be used to identify thermal defects such as insulation flaws and energy leaks.
Another potential market is in architectural predesign, where the backpack system can replace the cumbersome tying together of individual photographs to create a visual representation of the space. Approximate 2D floor plans can also be quickly created, avoiding the time-consuming process of manually measuring every dimension with a laser pointer. Since updated floor plans are needed for every remodeling or energy retrofitting project and do not exist for many buildings, this latter capability can be especially useful.
Zakhor and her team are working on a much smaller, lighter version of the system while simultaneously exploring potential avenues for commercialization. Despite the current constraints of the backpack, Zakhor doesn’t discount the idea that it could be a disruptive technology in the BIM market and beyond. “I think initially it will just provide another dimension to how building data is acquired,” she says. “As time goes on and accuracy is improved, it could reach a point where it replaces static scanning in many applications. The whole system is about producing a point cloud in a cheap, fast way.”
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