Since three-dimensional surface texture can display texture information of an object better than its two-dimensional counterpart and can vary with scene illumination and the view angles, it is widely used in virtual reality, computer games and animation applications. Photometric Stereo, as one of the most effective technologies for capturing three-dimensional surface information, has attracted wide attention both from academic researchers and industrial fields. Uniform illumination is the essential condition for capturing and reconstructing surface heightmaps. In practice, non-uniform illumination leads to distorted surface heightmaps, such as distortion and aberration during the capture and reconstruction processes. This paper proposes and assesses a fast and self-adaptive method based on inverse-square law to correct non-uniform illumination for reconstruction of 3D surface heightmaps, and to eliminate the distortions. In order to objectively assess the performance of the illumination correction algorithm, average absolute gradient (AAG) is proposed to compare the surface heightmaps reconstructed using corrected illumination with those reconstructed without illumination correction. Experimental results show that the method is efficient and can produce convincing results. 相似文献
Multimedia Tools and Applications - Fine-grained recognition is a challenging task due to small intra-category variances. Most of the top-performing fine-grained recognition methods leverage parts... 相似文献
Yolk/shell (Y–S) hybrid nanoarchitectures, owing to the interior voids created for individualized catalyst applications, have emerged as new candidates for effectively isolating catalytic species. However, the well-defined hollow interiors with flexible core and shell compositions—such as noble-metal cores, metal-oxide cores, and widespread semiconductor shells—and a flexible anisotropic shape are far from the requirements. In particular, the introduction of catalytic noble metals or metal-oxide nanocrystals (NCs) with isotropic or anisotropic shapes into various hollow semiconductor structures with well-defined morphologies has been rarely reported but is urgently needed. Herein, we propose a strategy involving the careful sulfuration of as-prepared cavity-free core/shell NCs or metal-oxide NCs followed by phosphine-initialized cation-exchange reactions for preparing metal@semiconductor and metal oxide@semiconductor (II-VI) Y–S NCs. The geometry, size, and conformations of the core and shell are fully and independently considered. New and unprecendented metal@semiconductor and metal oxide@semiconductor (II-VI) Y–S NCs are prepared via widespread phosphine-initialized cation-exchange reactions.
Image segmentation is the basis of image analysis, object tracking, and other fields. However, image segmentation is still a bottleneck due to the complexity of images. In recent years, fuzzy clustering is one of the most important selections for image segmentation, which can retain information as much as possible. However, fuzzy clustering algorithms are sensitive to image artifacts. In this study, an improved image segmentation algorithm based on patch-weighted distance and fuzzy clustering is proposed, which can be divided into two steps. First, the pixel correlation between adjacent pixels is retrieved based on patch-weighted distance, and then the pixel correlation is used to replace the influence of neighboring information in fuzzy algorithms, thereby enhancing the robustness. Experiments on simulated, natural and medical images illustrate that the proposed schema outperforms other fuzzy clustering algorithms.
