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Thursday, May 16 • 2:00pm - 2:30pm
(Imaging Tools/Techniques/& Tactics) Orthomosaics For Object Documentation

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Sometimes we have to record the condition of objects where the surface is too large to be recorded in a single digital image (walls, scrolls, textiles, elephants), or is partially occluded (undersides of objects close to the ground, objects obscured by other objects). These problems are compounded when we need to bring multiple images with different resolutions or camera positions into alignment (before and after images, infrared and ultraviolet images in multiband spectral imaging). Composite images provide one solution, and both general and specialist software packages (Photoshop, Gigapan, i2k) have be used to combine overlapping close-up images into high-resolution photomosaics and to provide approximate corrections of geometric distortion when bringing images with differing resolution or camera position into registration. A satisfactory-looking result can be obtained using these methods, but, in practice, it is hard to control distortion. The problem of controlling distortion is apparent for approximately two-dimensional objects (scrolls, paintings on canvas), focus blur and parallax error increase the problems of making reasonably faithful composite images of more three-dimensional objects. In this paper I discuss how photogrammetry provides solutions to some of these problems. Photogrammetry can be used to calculate a three-dimensional model of an object or surface and then the photographs used to make the model are orthorectified on the model’s surface and projected to form a single high-resolution, distortion-free two-dimensional image called an orthomosaic. In addition, manipulating the 3D model derived from photogrammetry allows us produce remove occlusions to provide orthomosaics documenting otherwise hidden surfaces. Finally, 3D model registration techniques can be used bring multiband images, or before and after image sets, into registration to produce well-aligned orthomosaics from different camera positions and sensor resolutions.

Speakers
avatar for JP Brown

JP Brown

Regenstein Conservator for Pacific Anthropology, The Field Museum
JP is the Regenstein Conservator for Pacific Anthropology at The Field Museum, Chicago. He holds degrees in both Archaeological Conservation and Computer Science. He started working on 3D imaging of museum collections in 2006 and has been doing CT, laser scanning, and photogrammetry... Read More →


Thursday May 16, 2019 2:00pm - 2:30pm EDT
Earth Ballroom A Earth Convention Center, Mohegan Sun
  General Session, Imaging Tools/Techniques/& Tactics
  • Ticketed Included in Main Registration
  • Authors in Publication Order JP Brown
  • Abstract ID 18746
  • Tags Documentation Photogrammetry Orthomosaic Image registration Multispectral imaging