Improved Correction Algorithm for Harmonic- and Intensity-Related Errors in Time-of-Flight Cameras

This study uses a B-spline surface error fitting function based on reflected light intensity and depth two-dimensional variable with additive weights to correct the weak light intensity-related depth error that occurs because of the low reflectivity or long distance of the target scene. In contrast to the traditional B-spline surface error fitting, the improved model uses weight parameters to optimize partial control points of each surface to obtain a more accurate error-fitting surface. It allows average correction errors to be less than 2 mm, which is nearly three times the accuracy of the traditional model. Furthermore, the additive weight parameter is added to each control point, which ensures that the parameter matrices of control points and additive weight can be obtained in a single step during the camera parameter calibration process, overcoming the issue that the multiplicative weight matrix cannot be obtained by the least squares method. Moreover, considering that the harmonic-related error is also connected to depth, the correction of the harmonic-related error is unified into the proposed correction method.