A Streamlined Photometric Stereo Framework for Cultural Heritage
In this paper, we propose a streamlined framework of robust 3D acquisition for cultural heritage using both photometric stereo and photogrammetric information. An uncalibrated photometric stereo setup is augmented by a synchronized secondary witness camer
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Department of EECS, Northwestern University, Evanston, USA [email protected] Northwestern University/Art Institute of Chicago Center for Scientific Studies in the Art (NU-ACCESS), Evanston, USA 3 Argonne National Laboratory, Lemont, USA
Abstract. In this paper, we propose a streamlined framework of robust 3D acquisition for cultural heritage using both photometric stereo and photogrammetric information. An uncalibrated photometric stereo setup is augmented by a synchronized secondary witness camera co-located with a point light source. By recovering the witness camera’s position for each exposure with photogrammetry techniques, we estimate the precise 3D location of the light source relative to the photometric stereo camera. We have shown a significant improvement in both light source position estimation and normal map recovery compared to previous uncalibrated photometric stereo techniques. In addition, with the new configuration we propose, we benefit from improved surface shape recovery by jointly incorporating corrected photometric stereo surface normals and a sparse 3D point cloud from photogrammetry. Keywords: Photometric stereo · Reflectance transformation imaging · Near light position calibration · Photogrammetry · 3D surface shape reconstruction
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Introduction
Computational Imaging techniques have been widely used for art history analysis and cultural heritage research in the last decade. Digital imaging technologies empower conservation scientists by revealing more information about works of art, helping to better preserve and protect their history for future generations. Accurate, automatic 3D surface recovery using only commodity cameras is particularly important for a number of applications in cultural heritage research. Since artifacts of historical significance are often located in public spaces or museums without the possibility of relocation to a laboratory environment, art conservators require 3D shape acquisition techniques that are portable, inexpensive, non-destructive, and fast, in order to uncover previously unknown information about artist techniques and materials. Two commonly used techniques that c Springer International Publishing Switzerland 2016 G. Hua and H. J´ egou (Eds.): ECCV 2016 Workshops, Part I, LNCS 9913, pp. 738–752, 2016. DOI: 10.1007/978-3-319-46604-0 51
A Streamlined Photometric Stereo Framework for Cultural Heritage
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Fig. 1. Overview of the Streamlined photometric stereo framework for cultural heritage: We use photogrammetry to find the 3D light positions [L1 , · · · , Lk ] relative to a stationary photometric stereo (PS) camera. The estimated 3D light positions then allow us to compute accurate surface normal N from the PS camera. We fuse the computed normal map with a depth map zˆ, computed using photogrammetry, to generate globally accurate 3D shapes Z with high-quality micro surface details.
fit these requirements are Reflectance Transformation Imaging (RTI) and Photogrammetry (PG). RTI is a visualization technique that allows users to probe the
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