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Item Dynamic SfM: Detecting Scene Changes from Image Pairs(The Eurographics Association and John Wiley & Sons Ltd., 2015) Wang, Tuanfeng Y.; Kohli, Pushmeet; Mitra, Niloy J.; Mirela Ben-Chen and Ligang LiuDetecting changes in scenes is important in many scene understanding tasks. In this paper, we pursue this goal simply from a pair of image recordings. Specifically, our goal is to infer what the objects are, how they are structured, and how they moved between the images. The problem is challenging as large changes make point-level correspondence establishment difficult, which in turn breaks the assumptions of standard Structure-from-Motion (SfM). We propose a novel algorithm for dynamic SfM wherein we first generate a pool of potential corresponding points by hypothesizing over possible movements, and then use a continuous optimization formulation to obtain a low complexity solution that best explains the scene recordings, i.e., the input image pairs. We test the algorithm on a variety of examples to recover the multiple object structures and their changes.Item Reforming Shapes for Material-aware Fabrication(The Eurographics Association and John Wiley & Sons Ltd., 2015) Yang, Yong-Liang; Wang, Jun; Mitra, Niloy J.; Mirela Ben-Chen and Ligang LiuAs humans, we regularly associate shape of an object with its built material. In the context of geometric modeling, however, this inter-relation between form and material is rarely explored. In this work, we propose a novel datadriven reforming (i.e., reshaping) algorithm that adapts an input multi-component model for a target fabrication material. The algorithm adapts both the part geometry and the inter-part topology of the input shape to better align with material-aware fabrication requirements. As output, we produce the reshaped model along with respective part dimensions and inter-part junction specifications. We evaluate our algorithm on a range of man-made models and demonstrate a variety of model reshaping examples focusing only on metal and wooden materials.Item An Image Degradation Model for Depth-augmented Image Editing(The Eurographics Association and John Wiley & Sons Ltd., 2015) Hennessey, James W.; Mitra, Niloy J.; Mirela Ben-Chen and Ligang LiuImages remain the most popular medium to capture our surroundings. Although significant advances have been made in developing image editing tools, the key challenge is to intelligently account for missing depth information. The growing popularity of depth images offers a new avenue to revisit image editing tasks. In this work, we investigate how even coarse depth information can be exploited to address some of the fundamental challenges in image editing namely producing correct perspective, handling occlusion, and obtaining segmentation. To this end, we propose a novel image degradation model that predicts how well an image edit can be performed in presence of coarse depth information. Technically, we create proxy geometry to summarize available depth information, and use it to predict occlusions and ordering between image patches, complete occluded regions, and anticipate image-level changes under camera movement. We evaluate the proposed image degradation model in the context of parallax photography from single depth images.Item SmartAnnotator: An Interactive Tool for Annotating Indoor RGBD Images(The Eurographics Association and John Wiley & Sons Ltd., 2015) Wong, Yu-Shiang; Chu, Hung-Kuo; Mitra, Niloy J.; Olga Sorkine-Hornung and Michael WimmerRGBD images with high quality annotations, both in the form of geometric (i.e., segmentation) and structural (i.e., how do the segments mutually relate in 3D) information, provide valuable priors for a diverse range of applications in scene understanding and image manipulation. While it is now simple to acquire RGBD images, annotating them, automatically or manually, remains challenging. We present SMARTANNOTATOR, an interactive system to facilitate annotating raw RGBD images. The system performs the tedious tasks of grouping pixels, creating potential abstracted cuboids, inferring object interactions in 3D, and generates an ordered list of hypotheses. The user simply has to flip through the suggestions for segment labels, finalize a selection, and the system updates the remaining hypotheses. As annotations are finalized, the process becomes simpler with fewer ambiguities to resolve. Moreover, as more scenes are annotated, the system makes better suggestions based on the structural and geometric priors learned from previous annotation sessions. We test the system on a large number of indoor scenes across different users and experimental settings, validate the results on existing benchmark datasets, and report significant improvements over low-level annotation alternatives. (Code and benchmark datasets are publicly available on the project page.)Item Replaceable Substructures for Efficient Part-Based Modeling(The Eurographics Association and John Wiley & Sons Ltd., 2015) Liu, Han; Vimont, Ulysse; Wand, Michael; Cani, Marie-Paule; Hahmann, Stefanie; Rohmer, Damien; Mitra, Niloy J.; Olga Sorkine-Hornung and Michael WimmerA popular mode of shape synthesis involves mixing and matching parts from different objects to form a coherent whole. The key challenge is to efficiently synthesize shape variations that are plausible, both locally and globally. A major obstacle is to assemble the objects with local consistency, i.e., all the connections between parts are valid with no dangling open connections. The combinatorial complexity of this problem limits existing methods in geometric and/or topological variations of the synthesized models. In this work, we introduce replaceable substructures as arrangements of parts that can be interchanged while ensuring boundary consistency. The consistency information is extracted from part labels and connections in the original source models. We present a polynomial time algorithm that discovers such substructures by working on a dual of the original shape graph that encodes inter-part connectivity. We demonstrate the algorithm on a range of test examples producing plausible shape variations, both from a geometric and from a topological viewpoint.Item Frontmatter: Pacific Graphics 2015(The Eurographics Association and John Wiley & Sons Ltd., 2015) Stam, Jos; Mitra, Niloy J.; Xu, Kun; -