Optimal depth estimation by combining focus measures using genetic programming

Three-dimensional (3D) shape reconstruction is a fundamental problem in machine vision applications. Shape From Focus (SFF) is one of the passive optical methods for 3D shape recovery that uses degree of focus as a cue to estimate 3D shape. In this approach, usually a single focus measure operator is applied to measure the focus quality of each pixel in the image sequence. However, the applicability of a single focus measure is limited to estimate accurately the depth map for diverse type of real objects. To address this problem, we develop Optimal Composite Depth (OCD) function through genetic programming (GP) for accurate depth estimation. The OCD function is constructed by optimally combining the primary information extracted using one/or more focus measures. The genetically developed composite function is then used to compute the optimal depth map of objects. The performance of the developed nonlinear function is investigated using both the synthetic and the real world image sequences. Experimental results demonstrate that the proposed estimator is more useful in computing accurate depth maps as compared to the existing SFF methods. Moreover, it is found that the heterogeneous function is more effective than homogeneous function.     

A SfM-based 3D face reconstruction method robust to self-occlusion by using a shape conversion matrix

This paper presents a 3D face reconstruction method using multiple 2D face images. Structure from motion (SfM) methods, which have been widely used to reconstruct 3D faces, are vulnerable to point correspondence errors caused by self-occlusion. In order to solve this problem, we propose a shape conversion matrix (SCM) which estimates the ground-truth 2D facial feature points (FFPs) from the observed 2D FFPs corrupted by self-occlusion errors. To make the SCM, the training observed 2D FFPs and ground-truth 2D FFPs are collected by using 3D face scans. An observed shape model and a ground-truth shape model are then built to represent the observed 2D FFPs and the ground-truth 2D FFPs, respectively. Finally, the observed shape model parameter is converted to the ground truth shape model parameter via the SCM. By using the SCM, the true locations of the self-occluded FFPs are estimated exactly with simple matrix multiplications. As a result, SfM-based 3D face reconstruction methods combined with the proposed SCM become more robust against point correspondence errors caused by self-occlusion, and the computational cost is significantly reduced. In experiments, the reconstructed 3D facial shape is quantitatively compared with the 3D facial shape obtained from a 3D scanner, and the results show that SfM-based 3D face reconstruction methods with the proposed SCM show a higher accuracy and a faster processing time than SfM-based 3D face reconstruction methods without the SCM.     

Orientation and anisotropy of multi-component shapes from boundary information

We define a method for computing the orientation of compound shapes based on boundary information. The orientation of a given compound shape S is taken as the direction α that maximises the integral of the squared length of projections, of all the straight line segments whose end points belong to particular boundaries of components of S to a line that has the slope α. Just as the concept of orientation can be extended from single component shapes to multiple components, elongation can also be applied to multiple components, and we will see that it effectively produces a measure of anisotropy since it is maximised when all components are aligned in the same direction. The presented method enables a closed formula for an easy computation of both orientation and anisotropy.     

Efficient shape optimization for certain and uncertain aerodynamic design

In this paper, we present novel developments in aerodynamic shape optimization based on shape calculus as well as the proper treatment of aleatoric uncertainties in the field of aerodynamic design.     

Accuracy and reliability of a technique for quantifying foot shape,dimensions and structural characteristics

A technique using a three-dimensional digitizing device for the measurements of foot dimension, shape and structural characteristics was developed. A total of 23 variables were calculated from the coordinates of 26 digitized points on the foot and the leg when body weight was supported mainly by one foot as the other foot was resting on a platform. All variables were measured with reference to an anatomically defined reference frame on the foot. The intra- and intertester reliability were tested both for the device and for the foot measurements. High reliability (ICC> 0.999) was found for the device in measuring distances and angles on a plastic cube. Intra- and intertester reliability for the foot measurements were high (ICC> 0.8) in most of the variables, with the lowest intratester reliability of 0.57 and the lowest intertester reliability of 0.38.     

Foot landmarking for footwear customization

As consumers are becoming increasingly selective of what they wear on their feet, manufacturers are experiencing problems developing and fitting the right footwear. Literature suggests that shoes with a shape similar to feet may be comfortable because they attempt to maintain the feet in a neutral posture. The objective of this paper is to develop a metric to quantify mismatches between feet and lasts and also to be able to generate the two-dimensional outline of the foot using the minimum number of landmarks. Fifty Hong Kong Chinese were participants in the experiment. In addition to subject weight, height, foot length and foot width, the left foot outlines were drawn and 18 landmarks were marked on each of the two-dimensional foot outlines. A step-wise procedure was used to reduce the chosen 18 landmarks to eight, such that the mean absolute negative error (an indicator of ‘tightness’) between the foot outline and the modelled curve was 1.3 mm. These eight landmarks seem to show an improvement over those proposed by other researchers, thus showing the importance of choosing the right landmarks for modelling the foot. The positive and negative absolute errors were on average 1.8 mm and 1.3 mm respectively. Moreover, the mean errors for the toe region and for the rest of the foot were 1.7 mm and 1.6 mm respectively. The results indicate that the foot outline, an important component for footwear functionality and fitting, may be modelled using eight critical landmarks.     

A Comparison of Three Types of Manual Controls on a Third-Order Tracking Task

Abstract

Three types of control levers— the spring-centrod-displaccment control, the on-off control and the pressure control— were compared on a third-order compensatory tracking task. Based on an analysis of the control transfer functions, the predicted ranking of the three controls is: (1) pressure, (2) displacement and (3) on-off. The results of a study in which five subjects tracked six trials with each control for 18 sessions were as follows. The data at the beginning of training indicated rankings of (1) pressure, (2) on-off and (3) displacement. However, the data taken during the latter sessions ranked the controls as predicted, although the difference between displacement and on-off was not statistically significant. Differences in results between, early and late training, and comparisons of these results with other studies, are discussed.     

Preliminary design and analysis of a cubic deployable support structure based on shape memory polymer composite

The deployable structures based on shape memory polymer composites (SMPCs) have been developed for its unique properties, such as high reliability, low-cost, lightweight, and self-deployment without complex mechanical devices compared with traditional deployable structures. In order to increase the inflatable structure system’s robustness and light the weight of it, a cubic deployable support structure based on SMPC is designed and analyzed preliminarily. The cubic deployable support structure based on SMPC consists of four dependent spatial cages, each spatial cage is composed of 12 three-longeron SMPC truss booms and end connections. The shape recovery of arc-shaped deployable laminates drive the three-longeron SMPC truss booms to unfold, thus realize the expansion of the deployable support structure. The concept and operation of the cubic deployable support structure are described in detail. A series of experiments are performed on the three-longeron deployable laminates unit and the simplified cubic deployable support structure to investigate the shape recovery behavior in the deployment process. Results indicate that the cubic deployable support structure has a high deployment-tgo-stowage volume ratio and can achieve self-deployment, package, and deploy without complex mechanical devices.     

Shape transformation by boundary representation interpolation: A recursive approach to establishing face correspondences

The issues relating to the shape transformation problem are discussed and a new algorithm is presented for computing the transformation of one shape into another. In this algorithm, the boundary definitions of the two initial shapes are used and a mapping is established between the vertices and edges of the respective objects. New vertices and edges are introduced into the object definitions when necessary to establish a one-to-one vertex correspondence and to match connectivity relationships between vertices. These can then be used to do a vertex-to-vertex interpolation that maintains valid polyhedral topologies for all of the intermediate shapes. The algorithm establishes a mapping between areas of the object such that adjacency relationships are preserved. These areas are recursively subdivided so that adjacency relationships of subareas are also preserved. During subdivision, vertices and edges are added to the boundaries of subareas so that a one-to-one mapping is established between them. Subdivision continues until each subarea consists of a single face. The algorithm presented works for objects that are topologically equivalent to spheres and can easily be extended to other pairs of objects as long as they are topologically equivalent to each other.     

磨边机磨头整体有限元建模及分析

用有限元方法对磨边机整体结构进行建模和动态分析 ,并探讨磨头磨块的不同分布形式对磨头结构动态特性的影响 ,发现磨块的分布是造成“狗牙”缺陷的主要因素之一 ,并选出动态特性较好的一种磨块分布形式用于整体结构 ,在实践应用中取得良好的效果。