Hybridization of Photogrammetry and Laser Scanning Technology for As-Built 3D CAD Models

摘要

Digital Mockups (Virtual Prototypes) significantly reduce risk and cost on large aerospace programs, but their accuracy hinges on the creation of 3D models of existing facilities, based on "as-built" field conditions instead of less-accurate design blueprints. Methods for creating as-built models vary from tedious hand-measurements, to photograph-rectification-survey techniques (collectively known as photogrammetry), to the evolving technology of terrestrial laser scanning. Lockheed Martin has proven through robust field testing that the accuracy of each technology is variable to specific applications. Therefore, we have developed a hybrid method that leverages the strengths of each technology, including edge recognition, targeting accuracy, and complex-surface collection. This hybridization has helped to identify key technical deficiencies in the current state-of-practice for as-built CAD modeling, such as automatic modeling and feature extraction. In addition, Lockheed Martin has refined a statistical evaluation technique to objectively measure the accuracy of the final model against the field conditions, regardless of the technology utilized. The advantages and disadvantages of each technology are presented here, as well as methodologies for effectively combining the technologies into a more-accurate and efficient hybrid process. This overall capability is crucial to Lockheed Martin for reducing reliance on physical prototypes, and optimizing project return on cost, schedule, and risk.