Methods of correction to extrinsic parameters in a stereoscopic vision with the assistance of two known-distance points

Stereoscopic vision plays a significant role in a three-dimensional measurement. With the calibrated intrinsic and extrinsic parameters, stereoscopic vision can complete an accurate measurement. However, the extrinsic parameters are inevitably disturbed by variations in the environment, such as vibration and assembly stress, resulting in a huge measurement error. To overcome the problem, with the assistance of two known-distance points, this Letter proposes correction methods based on triangulation and differential geometry, respectively. The methods formulate the distance and solve the corrected extrinsic parameters. Simulated and actual experiments are carried out, and the results show high accuracy and stability of the proposed methods.