Correcting two-dimensional kinematic errors for chick embryonic movements in ovo.

In motor behavior studies of chick embryos in ovo, kinematic recording is limited to a single camera system and produces kinematic data that are distorted if out-of-plane movements are not considered. CONVERT is a rule based algorithm designed to calculate 3D limb movements given 2D kinematic data. CONVERT's calculations are based on a stationary reference point, limited translation of the chick embryo's trunk point, a multi-linked model of the body, and approximate limb segment lengths. Simulations indicate CONVERT calculates joint movements from 2D data with a maximum error of 6 degrees compared to a maximum error of 79 degrees if out-of-plane considerations are ignored. The approach used to correct two-dimensional kinematic measurement errors can be readily applied to other experimental conditions that restrict video recording to single camera systems.