Boundary, Brightness, and Depth Interactions During Preattentive Representation and Attentive Recognition of Figure and Ground

This article applies a recent theory of 3-D biological vision, called FACADE Theory, to explain several percepts which Kanizsa pioneered. These include 3-D pop-out of an occluding form in front of an occluded form, leading to completion and recognition of the occluded form; 3-D transparent and opaque percepts of Kanizsa squares, with and without Varin wedges; and interactions between percepts of illusory contours, brightness, and depth in response to 2-D Kanizsa images. These explanations clarify how a partially occluded object representation can be completed for purposes of object recognition, without the completed part of the representation necessarily being seen. The theory traces these percepts to neural mechanisms that compensate for measurement uncertainty and complementarity at individual cortical processing stages by using parallel and hierarchical interactions among several cortical processing stages. These interactions are modelled by a Boundary Contour System (BCS) that generates emergent boundary segmentations and a complementary Feature Contour System (FCS) that fills-in surface representations of brightness, color, and depth. The BCS and FCS interact reciprocally with an Object Recognition System (ORS) that binds BCS boundary and FCS surface representations into attentive object representations. The BCS models the parvocellular LGN→Interblob→Interstripe→V4 cortical processing stream, the FCS models the parvocellular LGN→Blob→Thin Stripe→V4 cortical processing stream, and the ORS models inferotemporal cortex.Air Force Office of Scientific Research (F49620-92-J-0499); Defense Advanced Research Projects Agency (N00014-92-J-4015); Office of Naval Research (N00014-91-J-4100

Disparity-compensated view synthesis for s3D content correction

International audienceThe production of stereoscopic 3D HD content is considerably increasing and experience in 2-view acquisition is in progress. High quality material to the audience is required but not always ensured, and correction of the stereo views may be required. This is done via disparity-compensated view synthesis. A robust method has been developed dealing with these acquisition problems that introduce discomfort (e.g hyperdivergence and hyperconvergence...) as well as those ones that may disrupt the correction itself (vertical disparity, color difference between views...). The method has three phases: a preprocessing in order to correct the stereo images and estimate features (e.g. disparity range...) over the sequence. The second (main) phase proceeds then to disparity estimation and view synthesis. Dual disparity estimation based on robust block-matching, discontinuity-preserving filtering, consistency and occlusion handling has been developed. Accurate view synthesis is carried out through disparity compensation. Disparity assessment has been introduced in order to detect and quantify errors. A post-processing deals with these errors as a fallback mode. The paper focuses on disparity estimation and view synthesis of HD images. Quality assessment of synthesized views on a large set of HD video data has proved the effectiveness of our method

Hierarchical structural design for fracture resistance in the shell of the pteropod Clio pyramidata

The thecosomes are a group of planktonic pteropods with thin, 1 mm-sized aragonitic shells, which are known to possess a unique helical microstructure consisting of interlocking nanofibres. Here we investigate the detailed hierarchical structural and mechanical design of the pteropod Clio pyramidata. We quantify and elucidate the macroscopic distribution of the helical structure over the entire shell (~1 mm), the structural characteristics of the helical assembly (~10–100 μm), the anisotropic cross-sectional geometry of the fibrous building blocks (~0.5–10 μm) and the heterogeneous distribution of intracrystalline organic inclusions within individual fibres (<0.5 μm). A global fibre-like crystallographic texture is observed with local in-plane rotations. Microindentation and electron microscopy studies reveal that the helical organization of the fibrous building blocks effectively constrains mechanical damages through tortuous crack propagation. Uniaxial micropillar compression and cross-sectional transmission electron microscopy directly reveal that the interlocking fibrous building blocks further retard crack propagation at the nanometre scale.National Science Foundation (U.S.) ((Massachusetts Institute of Technology. Center for Materials Science and Engineering (DMR-0819762))United States. Army Research Office (Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract W911NF-07-D-0004))United States. Department of Defense. National Security Science and Engineering Faculty Fellow

Structured Light-Based 3D Reconstruction System for Plants.

Camera-based 3D reconstruction of physical objects is one of the most popular computer vision trends in recent years. Many systems have been built to model different real-world subjects, but there is lack of a completely robust system for plants. This paper presents a full 3D reconstruction system that incorporates both hardware structures (including the proposed structured light system to enhance textures on object surfaces) and software algorithms (including the proposed 3D point cloud registration and plant feature measurement). This paper demonstrates the ability to produce 3D models of whole plants created from multiple pairs of stereo images taken at different viewing angles, without the need to destructively cut away any parts of a plant. The ability to accurately predict phenotyping features, such as the number of leaves, plant height, leaf size and internode distances, is also demonstrated. Experimental results show that, for plants having a range of leaf sizes and a distance between leaves appropriate for the hardware design, the algorithms successfully predict phenotyping features in the target crops, with a recall of 0.97 and a precision of 0.89 for leaf detection and less than a 13-mm error for plant size, leaf size and internode distance

Macroporous materials: microfluidic fabrication, functionalization and applications

This article provides an up-to-date highly comprehensive overview (594 references) on the state of the art of the synthesis and design of macroporous materials using microfluidics and their applications in different fields

Three-Dimensional Liquid-Vapor Interface Reconstruction from High-Speed Stereo Images during Pool Boiling

A technique for reconstruction of liquid-gas interfaces based on high-speed stereo-imaging is applied to the liquid-vapor interfaces formed above a heated surface during pool boiling. Template matching is used for determining the correspondence of local features of the liquid-vapor interfaces between the two camera views. A sampling grid is overlaid on the reference image, and windows centered at each sampled pixel are compared with windows centered along the epipolar line in the target image to obtain a correlation signal. The three-dimensional coordinates of each matched pixel are determined via triangulation, which yields the physical world representation of the liquid-vapor interface. Liquid-vapor interface reconstruction is demonstrated during pool boiling for a range of heat fluxes. Textured mushroom-like vapor bubbles that are fed by multiple nucleation sites are formed close to the heated surface. Analysis of the temporal attributes of the interface distinguishes the transition with increasing heat flux from a mode in which vapor is released from the surface as a continuous plume to one dominated by the occurrence of intermittent vapor bursts. A characteristic morphology of the vapor mushroom formed during vapor burst events is identified. This liquid-vapor interface reconstruction technique is a time-resolved, flexible and non-invasive alternative to existing methods for phase-distribution mapping, and can be combined with other opticalbased diagnostic tools, such as tomographic particle image velocimetry. Vapor flow morphology characterization during pool boiling at high heat fluxes can be used to inform vapor removal strategies that delay the occurrence of critical heat flux during pool boiling