We present a near-lighting photometric stereo (NL-PS) system to produce digital bas-reliefs from a physical object (set) directly. Unlike both the 2D image and 3D model-based modelling methods that require complicated interactions and transformations, the technique using NL-PS is easy to use with cost-effective hardware, providing users with a trade-off between abstract and representation when creating bas-reliefs. Our algorithm consists of two steps: normal map acquisition and constrained 3D reconstruction. First, we introduce a lighting model, named the quasi-point lighting model (QPLM), and provide a two-step calibration solution in our NL-PS system to generate a dense normal map. Second, we filter the normal map into a detail layer and a structure layer, and formulate detail- or structure-preserving bas-relief modelling as a constrained surface reconstruction problem of solving a sparse linear system. The main contribution is a WYSIWYG (i.e. what you see is what you get) way of building new solvers that produces multi-style bas-reliefs with their geometric structures and/or details preserved. The performance of our approach is experimentally validated via comparisons with the state-of-the-art methods.
Bibliographical noteThe authors would like to thank the anonymous AE and reviewers for their valuable comments. The authors thank Mr. Li Zhang for providing the inputs in Figure. This work was supported by the grants from the National Natural Science Foundation of China (No. 61502137, No. 61672510, No. 61772267 and No. 51705513), the Shenzhen Science Plan (No. KQJSCX20170731165108047), the Interdisciplinary Research Scheme of the Dean's Research Fund 2018-19 (FLASS/DRF/IDS-3), Top-Up Fund (TFG-04) and Seed Fund (SFG-10) for General Research Fund/Early Career Scheme of the Dean's Research Fund 2018-19 of The Education University of Hong Kong, Shenzhen Basic Research Program (No. JCYJ20170412174037594) and the State Key Laboratory for Novel Software Technology, Nanjing University (No. KFKT2018B20).
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- compression algorithms
- computational geometry
- curves and surfaces
- Computing methodologies → Shape analysis