A conformal oblique projection method based on double projection

To address multi-zone Gaussian projection challenges in large-scale long-distance water diversion projects, this study proposes a conformal oblique projection method based on double projection, encompassing both forward and inverse calculation models. Case studies demonstrate that the method is theoretically sound and practically reliable. It effectively constrains length projection deformation while ensuring conformal projection, and enables high-precision mutual conversion between basic-ellipsoid geodetic coordinates and engineering plane rectangular coordinates. This meets the core requirements of large-scale, long-distance water diversion projects for an engineering plane rectangular coordinate system, including high precision, high reliability, and highly continuous coordinates throughout the entire project.