  Advancements in optical metrology has enabled documentation of dense 3D point
clouds of cultural heritage sites. For large scale and continuous digital
documentation, processing of dense 3D point clouds becomes computationally
cumbersome, and often requires additional hardware for data management,
increasing the time cost, and complexity of projects. To this end, this
manuscript presents an original approach to generate fast and reliable semantic
digital models of heritage hemispherical domes using only two images. New
closed formulations were derived to establish the relationships between spheres
and their projected ellipses onto images, which fostered the development of a
new automatic framework for as-built generation of spheres. The effectiveness
of the proposed method was evaluated under both laboratory and real-world
datasets. The results revealed that the proposed method achieved as-built
modeling accuracy of around 6mm, while improving the computation time by a
factor of 7, when compared to established point cloud processing methods.
