Please use this identifier to cite or link to this item: http://hdl.handle.net/11400/8075
Title: Data fusion from multiple sources for the production of orthographic and perspective views with automatic visibility checking
Authors: Γραμματικόπουλος, Λάζαρος
Καλησπεράκης, Ηλίας
Καρράς, Γιώργος
Πέτσα, Έλλη
Item type: Conference publication
Conference Item Type: Full Paper
Keywords: Automation;Visualization;Orthorectification;Ορθοαναγωγή;DEM/DTM;Laser scanning;Σάρωση laser;Αυτοματοποίηση;Οραματισμός
Subjects: Topography
Geodesy
Τοπογραφία
Γεωδαισία
Issue Date: 17-Mar-2015
Date of availability: 17-Mar-2015
Abstract: Orthophotography – and photo-textured 3D surface models, in general – are most important photogrammetric products in heritageconservation. However, it is now common knowledge that conventional orthorectification software accepts only surface descriptionsobtained via 2D triangulation and cannot handle the question of image visibility. Ignoring multiple surface elevations and image occlusionsof the complex surface shapes, typically met in conservation tasks, results in products visually and geometrically distorted.Tiresome human intervention in the surface modeling and image orthorectification stages might partly remedy this shortcoming. Forsurface modeling, however, laser scanners allow now collection of numerous accurate surface points and creation of 3D meshes. Theauthors present their approach for an automated production of correct orthoimages (and perspective views), given a multiple imagecoverage with known calibration/orientation data and fully 3D surface representations derived through laser scanning. The developedalgorithm initially detects surface occlusions in the direction of projection. Next, all available imagery is utilised to establish a colourvalue for each pixel of the new image. After back-projecting (using the bundle adjustment data) all surface triangles onto all initialimages to establish visibilities, texture ‘blending’ is performed. Suitable weighting controls the local radiometric contribution of eachparticipating source image, while outlying colour values (due mainly to registration and modeling errors) are automatically filteredwith a simple statistical test. The generation of a depth map for each original image provides a means to further restrict the effects oforientation and modeling errors on texturing, mainly by checking closeness to occlusion borders. This ‘topological’ information mayalso allow establishing suitable image windows for colour interpolation. Practical tests of the implemented algorithm, using imageswith multiple overlap and two 3D models, indicate that this fusion of laser scanner and photogrammetry is indeed capable to automaticallysynthesize novel views from multiple images. The developed approach, combining an outcome of geometric accuracy andvisual quality with speed, appears as a realistic approach in heritage conservation. Further necessary elaborations are also outlined.
Language: English
Conference: Proc. XX CIPA International Symposium
Access scheme: Publicly accessible
License: Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ηνωμένες Πολιτείες
URI: http://hdl.handle.net/11400/8075
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