Hybridization ofPhotogrammetry andLaserScanning Technology forAs-Built 3DCAD Models

DigitalMockups (VirtualPrototypes) significantly reduce riskandcoston large aerospace programs, buttheir accuracy hinges onthecreation of3D modelsofexisting facilities, basedon"as-built" field conditions instead of less-accurate design blueprints. Methods forcreating as-built modelsvaryfromtedious hand-measurements, to photograph-rectification-survey techniques (collectively knownasphotogrammetry), tothe evolving technology ofterrestrial laser scanning. Lockheed Martin hasproven through robust field testing that theaccuracy ofeachtechnology isvariable tospecific applications. Therefore, we havedeveloped a hybrid methodthatleverages thestrengths ofeachtechnology, including edgerecognition, targeting accuracy, and complex-surface collection. Thishybridization hashelped toidentify keytechnical deficiencies inthecurrent state-of- practice foras-built CAD modeling, suchasautomatic modeling andfeature extraction. Inaddition, Lockheed Martin hasrefined a statistical evaluation technique to objectively measure theaccuracy ofthefinal modelagainst thefield conditions, regardless ofthetechnology utilized. Theadvantages anddisadvantages ofeachtechnology are presented here, aswellasmethodologies foreffectively combining thetechnologies intoa more-accurate and efficient hybrid process. Thisoverall capability iscrucial to LockheedMartinforreducing reliance on physical prototypes, andoptimizing project return oncost, schedule, andrisk.'2