An analytical and digital photogrammetric study of the ‘Sirius’

Abstract

The Sirius, a staysail schooner measuring 53 1/2 feet (16 m) and captained by Harold Nossiter, departed from Sydney in June 1935 to become the first Australian designed and built yacht to circumnavigate the world. A hull plan of the Sirius was reproduced in one of Harold Nossiter's books detailing his epic voyage, but little dimensional evidence exists of the masts, spars, rigging, etc. above deck. One large photographic print in the possession of the Nossiter family, the frontispieces from two of Harold Nossiter's books, three other photographic plates from one of his books and five frames of videoimages taken from Movietone News footage of the Sirius returning to Sydney were scanned into images suited to a Macintosh computer. Coordinates of 248 points of interest were digitised from the computer screen of these eleven images and analysed in a bundle adjustment to determine the dimensions of the superstructure. Considerable difficulties such as a lack of information about the original cameras, their focal lengths and distortions, cropped photographs, film to video to computer screen distortions and the flexible nature of the mast and riggings photographed under different wind conditions were experienced during the computer processing. The final results indicate an accuracy better than ± 3 inches (± 7 cm) on the yacht and that certain features on the deck were not built according to the design plan