Computational themes in applications of visual perception

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76646/1/AIAA-1987-1674-988.pd

A classification scheme for visual defects arising in semiconductor wafer inspection

In this paper we describe a novel scheme to characterize surface defects and flaws that arise in semiconductor wafer processing. This is done by analyzing the texture of an image of the defect. We have developed a taxonomy for textures, which classifies textures into the broad classes of disordered, strongly ordered and weakly ordered. Disordered textures are described in terms of their fractal dimension, strongly ordered textures are by the placement of primitives, and weakly ordered textures by the underlying orientation field. We have developed an algorithm to measure the fractal dimension of a given texture. We use the qualitative theory of differential equations to devise a symbol set for the weakly ordered textures in terms of singularities. We have devised an algorithm to process an image of a defect and extract qualitative descriptions based on this theory.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28525/1/0000322.pd

Invariant surface characteristics for 3D object recognition in range images

In recent years there has been a tremendous increase in computer vision research using range images (or depth maps) as sensor input data. The most attractive feature of range images is the explicitness of the surface information. Many industrial and navigational robotic tasks will be more easily accomplished if such explicit depth information can be efficiently obtained and interpreted. Intensity image understanding research has shown that the early processing of sensor data should be data-driven. The goal of early processing is to generate a rich description for later processing. Classical differential geometry provides a complete local description of smooth surfaces. The first and second fundamental forms of surfaces provide a set of differential-geometric shape descriptors that capture domain-independent surface information. Mean curvature and Gaussian curvature are the fundamental second-order surface characteristics that possess desirable invariance properties and represent extrinsic and intrinsic surface geometry respectively. The signs of these surface curvatures are used to classify range image regions into one of eight basic viewpoint-independent surface types. Experimental results for real and synthetic range images show the properties, usefulness, and importance of differential-geometric surface characteristics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26326/1/0000413.pd

Motion detection in spatio-temporal space

We present an analysis of existing motion detectors for determining desirable characteristics of a motion detector. A spatio-temporal surface type inseparable model is then proposed for motion detection. Based on this model, we analyzed mathematically how the geometry of the intensity hypersurface gives information about motion in image. The local motion information, obtained from the parameters of the Monge patch approximating the intensity hypersurface in the spatio-temporal space, may be used for segmentation of dynamic scenes. Motion detection results for real sequences show the robustness of this detector.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28157/1/0000609.pd

Recovering a boundary-level structural description from dynamic stereo

We present a stereo algorithm to recursively compute a boundary-level structural description of a static scene, from a sequence of dynamic stereo images. This algorithm is based on connected line segments as the basic match primitive, which yields a description composed primarily of boundaries of objects in the scene. The algorithm is integrated into a dynamic stereo vision system to compute and incrementally refine such a structural description recursively, using belief measures. The approach is illustrated with a real dynamic stereo sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30120/1/0000496.pd

Collaborative online learning of user generated content

Ministry of Education, Singapore under its Academic Research Funding Tier

Collaborative online multitask learning

Ministry of Education, Singapore under its Academic Research Funding Tier

Structural Characterisation of Printable Noble Metal/Poly(Vinyl-­Alcohol) Nanocomposites for Optical Applications

This work was conducted under the aegis of the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom (EP/I004173/1). Amin Abdolvand is an EPSRC Career Acceleration Fellow at the University of Dundee.In order to enable exploitation of noble metal/poly(vinyl-alcohol) nanocomposites for device fabrication, solutions of poly(vinyl-alcohol) suitable for piezo-driven inkjet printing techniques are identified and discussed in terms of their material properties. The printable poly(vinyl-alcohol) medium is then exploited as a host material through the formation of silver or gold nanoparticles in order to create nanocomposites that exhibit a surface plasmon resonance behaviour associated with the small metallic inclusions. To mitigate some of the material redistribution effects associated with the drying of printed droplets containing finely divided materials, the metallic nanoparticles are formed after the printing and drying process is completed, by way of an in-situ reduction of an appropriate metal salt by the poly(vinyl-alcohol)-host matrix itself, which takes place at modest temperatures compatible with most substrate materials. An obvious application for such nanocomposites is in optical elements whereby the surface plasmon resonance associated with the metal is the functional aspect of devices such as sensors or active optical elements. High Resolution Transmission Electron Microscopy was used to examine the dimensions, distribution, morphology and crystal structure of the silver and gold nanoparticles in detail allowing discussion of their suitability for these applications and what further optimisation may be necessary to adequately control their formation.Publisher PDFPeer reviewe