Figure 1: Our reconstruction pipeline. From left to right: (a) semantically labeled 3D point cloud; (b) reconstructed objects using categoryspecific methods, including billboard trees, replaced common objects, and a building. The color-code on the building shows recognized different building parts; (c) textured 3D models on a ground plane, and (d) an overview of an automatically reconstructed large-scale scene. AbstractWe present a complete system to semantically decompose and reconstruct 3D models from point clouds. Different than previous urban modeling approaches, our system is designed for residential scenes, which consist of mainly low-rise buildings that do not exhibit the regularity and repetitiveness as high-rise buildings in downtown areas. Our system first automatically labels the input into distinctive categories using supervised learning techniques. Based on the semantic labels, objects in different categories are reconstructed with domain-specific knowledge. In particular, we present a novel building modeling scheme that aims to decompose and fit the building point cloud into basic blocks that are blockwise symmetric and convex. This building representation and its reconstruction algorithm are flexible, efficient, and robust to missing data. We demonstrate the effectiveness of our system on various datasets and compare our building modeling scheme with other state-of-the-art reconstruction algorithms to show its advantage in terms of both quality and speed.

Abstract. Head pose estimation is an important task for many face analysis applications, such as face recognition systems and human computer interactions. In this paper we aim to address the pose estimation problem under some challenging conditions, e.g., from a single image, large pose variation, and un-even illumination conditions. The approach we developed combines non-linear dimension reduction techniques with a learned distance metric transformation. The learned distance metric provides better intra-class clustering, therefore preserving a smooth lowdimensional manifold in the presence of large variation in the input images due to illumination changes. Experiments show that our method improves the performance, achieving accuracy within 2-3 degrees for face images with varying poses and within 3-4 degrees error for face images with varying pose and illumination changes.

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Abstract. This paper presents a new approach to synthesize face images under different pose changes given a single input image. The approach is based on two observations: 1. a series of face images of a single person under different poses could be mapped to a smooth manifold in the unified feature space. 2. the manifolds from different faces are separated from each other by their dissimilarities. The new manifold estimation is formulated as an energy minimization problem with smoothness constraints. The experiments show that face images under different poses can be robustly synthesized from one input image, even with large pose variations.

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