Angel Sappa, & M.A. Garcia. (2007). Generating compact representations of static scenes by means of 3D object hierarchies. The Visual Computer, 23(2): 143–154.
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Angel Sappa, & M.A. Garcia. (2007). Coarse-to-Fine Approximation of Range Images with Bounded Error Adaptive Triangular Meshes. Journal of Electronic Imaging, 16(2), 023010(11 pages).
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Angel Sappa, & M.A. Garcia. (2007). Incremental Integration of Multiresolution Range Images. The imaging science journal. Vol. 55, No. 3 pp. 127–139.
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Angel Sappa, & M.A. Garcia. (2007). Aprendiendo a recrear la realidad en 3D. UAB Divulga, Revista de Divulgacion Cientifica.
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Angel Sappa, & Mohammad Rouhani. (2009). Efficient Distance Estimation for Fitting Implicit Quadric Surfaces. In 16th IEEE International Conference on Image Processing (3521–3524).
Abstract: This paper presents a novel approach for estimating the shortest Euclidean distance from a given point to the corresponding implicit quadric fitting surface. It first estimates the orthogonal orientation to the surface from the given point; then the shortest distance is directly estimated by intersecting the implicit surface with a line passing through the given point according to the estimated orthogonal orientation. The proposed orthogonal distance estimation is easily obtained without increasing computational complexity; hence it can be used in error minimization surface fitting frameworks. Comparisons of the proposed metric with previous approaches are provided to show both improvements in CPU time as well as in the accuracy of the obtained results. Surfaces fitted by using the proposed geometric distance estimation and state of the art metrics are presented to show the viability of the proposed approach.
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Angel Sappa, Niki Aifanti, N. Grammalidis, & Sotiris Malassiotis. (2004). Advances in Vision-Based Human Body Modeling. In N. Sarris and M. Strintzis. (Ed.), 3D Modeling & Animation: Systhesis and Analysis Techniques for the Human Body (pp. 1–26).
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Angel Sappa, Niki Aifanti, Sotiris Malassiotis, & Michael G. Strintzis. (2003). Monocular 3D Human Body Reconstruction Towards Depth Augmentation of Television Sequences. In IEEE International Conference on Image Processing, Barcelona, Spain, September 2003 (pp. 325–328).
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Angel Sappa, Niki Aifanti, Sotiris Malassiotis, & Michael G. Strintzis. (2004). Unsupervised Motion Classification by means of Efficient Feature Selection and Tracking.
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Angel Sappa, Niki Aifanti, Sotiris Malassiotis, & Michael G. Strintzis. (2004). 3D Human Walking Modelling.
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Angel Sappa, Niki Aifanti, Sotiris Malassiotis, & Michael G. Strintzis. (2004). 3D Gait Estimation from Monoscopic Video.
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Angel Sappa, Niki Aifanti, Sotiris Malassiotis, & Michael G. Strintzis. (2005). Prior Knowledge Based Motion Model Representation. Electronic Letters on Computer Vision and Image Analysis, Special Issue on Articulated Motion & Deformable Objects, 5(3):55–67 (Electronic Letters: IF: 1.016).
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Angel Sappa, Niki Aifanti, Sotiris Malassiotis, & Michael G. Strintzis. (2009). Prior Knowledge Based Motion Model Representation. In Horst Bunke, JuanJose Villanueva, & Gemma Sanchez (Eds.), Progress in Computer Vision and Image Analysis (Vol. 16).
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Angel Sappa, Niki Aifanti, Sotiris Malassiotis, & N. Grammalidis. (2005). Survey of 3D Human Body Representations. In Encyclopedia of Information Science and Technology, 1(5):2696–2701.
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Angel Sappa, P. Carvajal, Cristhian A. Aguilera-Carrasco, Miguel Oliveira, Dennis Romero, & Boris X. Vintimilla. (2016). Wavelet based visible and infrared image fusion: a comparative study. SENS - Sensors, 16(6), 1–15.
Abstract: This paper evaluates different wavelet-based cross-spectral image fusion strategies adopted to merge visible and infrared images. The objective is to find the best setup independently of the evaluation metric used to measure the performance. Quantitative performance results are obtained with state of the art approaches together with adaptations proposed in the current work. The options evaluated in the current work result from the combination of different setups in the wavelet image decomposition stage together with different fusion strategies for the final merging stage that generates the resulting representation. Most of the approaches evaluate results according to the application for which they are intended for. Sometimes a human observer is selected to judge the quality of the obtained results. In the current work, quantitative values are considered in order to find correlations between setups and performance of obtained results; these correlations can be used to define a criteria for selecting the best fusion strategy for a given pair of cross-spectral images. The whole procedure is evaluated with a large set of correctly registered visible and infrared image pairs, including both Near InfraRed (NIR) and Long Wave InfraRed (LWIR).
Keywords: Image fusion; fusion evaluation metrics; visible and infrared imaging; discrete wavelet transform
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Angel Sappa, Patricia Suarez, Henry Velesaca, & Dario Carpio. (2022). Domain Adaptation in Image Dehazing: Exploring the Usage of Images from Virtual Scenarios. In 16th International Conference on Computer Graphics, Visualization, Computer Vision and Image Processing (pp. 85–92).
Abstract: This work presents a novel domain adaptation strategy for deep learning-based approaches to solve the image dehazing
problem. Firstly, a large set of synthetic images is generated by using a realistic 3D graphic simulator; these synthetic
images contain different densities of haze, which are used for training the model that is later adapted to any real scenario.
The adaptation process requires just a few images to fine-tune the model parameters. The proposed strategy allows
overcoming the limitation of training a given model with few images. In other words, the proposed strategy implements
the adaptation of a haze removal model trained with synthetic images to real scenarios. It should be noticed that it is quite
difficult, if not impossible, to have large sets of pairs of real-world images (with and without haze) to train in a supervised
way dehazing algorithms. Experimental results are provided showing the validity of the proposed domain adaptation
strategy.
Keywords: Domain adaptation; Synthetic hazed dataset; Dehazing
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