Please use this identifier to cite or link to this item: http://hdl.handle.net/11400/5039
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: Orthorectification;DEM/DTM;Laser scanning;Automation;Visualization;Ορθοαναγωγή;Σάρωση λέιζερ;Αυτοματισμός;Νοερά απεικόνηση
Subjects: Technology
Photogrammetry
Τεχνολογία
Φωτογραμμετρία
Issue Date: 29-Jan-2015
27-Sep-2005
Date of availability: 29-Jan-2015
Abstract: Orthophotography – and photo-textured 3D surface models, in general – are most important photogrammetric products in heritage conservation. However, it is now common knowledge that conventional orthorectification software accepts only surface descriptions obtained via 2D triangulation and cannot handle the question of image visibility. Ignoring multiple surface elevations and image oc-clusions of 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. For surface modeling, however, laser scanners allow now collection of numerous accurate surface points and creation of 3D meshes. The authors present their approach for an automated production of correct orthoimages (and perspective views), given a multiple image coverage with known calibration/orientation data and fully 3D surface representations derived through laser scanning. The developed algorithm initially detects surface occlusions in the direction of projection. Next, all available imagery is utilised to establish a colour value for each pixel of the new image. After back-projecting (using the bundle adjustment data) all surface triangles onto all initial images to establish visibilities, texture ‘blending’ is performed. Suitable weighting controls the local radiometric contribution of each participating source image, while outlying colour values (due mainly to registration and modeling errors) are automatically filtered with a simple statistical test. The generation of a depth map for each original image provides a means to further restrict the effects of orientation and modeling errors on texturing, mainly by checking closeness to occlusion borders. This ‘topological’ information may also allow establishing suitable image windows for colour interpolation. Practical tests of the implemented algorithm, using images with multiple overlap and two 3D models, indicate that this fusion of laser scanner and photogrammetry is indeed capable to automa-tically synthesize novel views from multiple images. The developed approach, combining an outcome of geometric accuracy and visual quality with speed, appears as a realistic approach in heritage conservation. Further necessary elaborations are also outlined.
Language: English
Citation: Grammatikopoulos, L., Kalisperakis, I., Karras, G. and Petsa, E. (2005). Data fusion from multiple sources for the production of orthographic and perspective views with automatic visibility checking. Proc. XX CIPA International Symposium, Torino, 27/9 - 1/10/2005, pp. 819-824. Available from: http://cipa.icomos.org/fileadmin/template/doc/TURIN/819.pdf.
Conference: 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/11400/5039
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