Structured light scanning normally requires a projector and camera to be synchronized. A new technique developed by Brown University researchers eliminates the need for synchronization, which makes it possible to do structured light scanning with a smartphone.
Most professional 3D scanners capture images using a technique known as structured light. A projector casts a series of light patterns on an object, while a camera captures images of the object. The ways in which those patterns deform over and around an object can be used to render a 3D image. But for the technique to work, the pattern projector and the camera have to be precisely synchronized, which requires specialized and expensive hardware.
The algorithm Gabriel Taubin, associate professor of engineering and computer science, and his students have developed, however, enables the structured light technique to be done without synchronization between projector and camera, which means an off-the-shelf camera can be used with an untethered structured light flash. The camera just needs to have the ability to capture uncompressed images in burst mode (several successive frames per second), which many DSLR cameras and smartphones can do.
After the camera captures a burst of images, the algorithm calibrates the timing of the image sequence using the binary information embedded in the projected pattern. Then it goes through the images, pixel by pixel, to assemble a new sequence of images that captures each pattern in its entirety. Once the complete pattern images are assembled, a standard structured light 3D reconstruction algorithm can be used to create a single 3D image of the object or space.
During testing, the researchers used a standard structured light projector, but the team envisions working to develop a structured light flash that could eventually be used as an attachment to any camera, now that there's an algorithm that can properly assemble the images.