On the Efficient Design and Implementation of Systolic Structures

Computing and Information Scienc

Mapping image processing operations onto a linear systolic machine

Computer Science Departmen

Latency Measurement, Modelling and Management for Interactive Remote Rendering

Ph. D. ThesisInteractive Remote Rendering (IRR) systems enable computationally intensive rendering tasks to be offloaded to powerful remote servers, while permitting real-time user interaction. By streaming only images from the server to the client, these systems solve many issues, but can be adversely affected by Interaction Latency (IL). This thesis explores the use of keyboard-based user interaction prediction as a potential method for reducing IL. Specifically, the following questions are addressed: What is the effect of prediction on IL? How can we model and simulate latency? How can we measure IL when prediction is used? What is the optimal number of predictions ahead required to minimise latency? On which side of the network should prediction be performed? The literature describes a few cases of prediction being used in IRR systems but there exists a lack of knowledge pertaining to the development, integration and measurement of prediction into such systems. Initial investigation identified a lack of robust techniques for simulating and measuring latency in IRR systems, especially those employing prediction. A latency model is introduced, and a simulator is developed, demonstrating results comparable to the real-world. Latency simulation is shown to be accurate and is integrated into a “IRR simulator platform”, permitting the exploration of the above research questions. As a result, two novel latency measurement techniques are presented. A prediction module is then developed and used in conjunction with the simulator platform. Results show that IL can be substantially reduced but predicting too far ahead negatively impacts IL, while less interaction history is found to result in lower mean IL. Finally, Client-Side Prediction was found to be more favourable for IL with respect to the amount of interaction history used, while Server-Side Prediction is shown to facilitate lower IL when predicting more than one step ahead. The results and tools presented in this thesis should prove useful for future exploration of PIRR systems.EPSR

Visual inspection : image sampling, algorithms and architectures

The thesis concerns the hexagonal sampling of images, the processing of industrially derived images, and the design of a novel processor element that can be assembled into pipelines to effect fast, economic and reliable processing. A hexagonally sampled two dimensional image can require 13.4% fewer sampling points than a square sampled equivalent. The grid symmetry results in simpler processing operators that compute more efficiently than square grid operators. Computation savings approaching 44% arc demonstrated. New hexagonal operators arc reported including a Gaussian smoothing filter, a binary thinner, and an edge detector with comparable accuracy to that of the Sobel detector. The design of hexagonal arrays of sensors is considered. Operators requiring small local areas of support are shown to be sufficient for processing controlled lighting and industrial images. Case studies show that small features in hexagonally processed images maintain their shape better, and that processes can tolerate a lower signal to noise ratio, than that for equivalent square processed images. The modelling of small defects in surfaces has been studied in depth. The flexible programmable processor element can perform the low level local operators required for industrial image processing on both square and hexagonal grids. The element has been specified and simulated by a high level computer program. A fast communication channel allows for dynamic reprogramming by a control computer, and the video rate element can be assembled into various pipeline architectures, that may eventually be adaptively controlled