Development of a Novel Photogrammetry Method for Acquiring 3D Surface Models of Infant Clubfoot Anatomy

We have developed a mobile photogrammetry cart, which can be used to obtain 3D surface models of infant leg anatomy. The purpose is to assess infants with idiopathic clubfoot by providing quantitative data. Traditional methods of 3D scanning are not suitable for infants since they will not stay still for any length of time. The system consists of 40 Raspberry Pi's, each equipped with a high-quality camera module. The cameras are mounted on t-slotted framing with custom 3D printed ball joints. The Raspberry Pi's are connected through an ethernet switch to a laptop that serves as a controller. We modified an Evenflo Exersaucer Activity Seat to safely expose the legs to the cameras in an unobstructed manner. For scaling, registration markers are engraved on a two-toned, laser cut plate mounted underneath the infant's seat. A custom application controls the Raspberry Pi's to take synchronized photos, saving them to network attached storage. Post-processing is completed in Agisoft Metashape, which generates an exact 3D model from the 2D images. We initially tested the system with a healthy, two-month-old infant with the permission of her parents. We successfully obtained 3D surface models of the volunteer's feet and lower legs, demonstrating the feasibility of the system. Our next step is to collect clubfoot data from our orthopedic clinic in an Institutional Review Board (IRB) approved study. To date, we have enrolled one two-week-old patient with bilateral clubfoot, and successfully collected a 3D surface model of their condition prior to their first corrective casting.