Ken Brodlie - Research Page


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Overview

My research interests cover the spectrum of visualization as a discipline - from foundations to applications; from systems to algorithms; from scientific visualization to information visualization; from data visualization to computational steering; from abstract visualizations to modelling reality.  A recent unifying theme has been the use of visualization in e-science - with a number of research projects funded under the UK e-Science initiative..

This work is carried out within the wider Visualization and Virtual Reality Research Group at Leeds, and is done in close collaboration with a number of staff and students at Leeds; with colleagues at other universities through joint research projects; and with industry - in particular, NAG Ltd.

Visualization Systems

Our work aims to extend current visualization systems in three directions: collaborative visualization, computational steering, and the incorporation of visualization in Web- and Grid-based environments.  Much of this work has been done in collaboration with Jason Wood, and more recently James Handley, Chris Goodyer and Jungwook Seo.  Two Eurographics State-of-the-Art reports have been presented in this area, and subsequently published in Computer Graphics Forum (Distributed and Collaborative Visualization and Visual Supercomputing: Technologies, Applications and Challenges).

Our recent work is highlighted in three e-Science projects: gViz, e-Viz and Integrative Biology:



gviz project

 The gViz project - in collaboration with the Universities of Oxford and Oxford Brookes, CCLRC/RAL, and three industrial companies: NAG, IBM UK and Streamline - was carried out under the UK e-science core programme in the period 2002-04.  It studied visualization middleware for e-science - focusing on how to evolve visualization systems to Grid computing. Specifically it extended IRIS Explorer to work in a secure, distributed fashion, with the modules in the visualization pipeline executing on remote Grid resources.  It is expected that this software will be available in the next release of IRIS Explorer from NAG Ltd.  The project also studied computational steering in Grid environments, developing a library, the gViz library, that allows a simulation running remotely on the Grid to be monitored and controlled from the desktop.  An important contribution of gViz, due largely to Oxford Brookes, was the development of skML, an XML language to describe the syntax of dataflow visualization.  The gViz project has built on our earlier work on collaborative visualization - specifically, the EPSRC COVISA project which showed how dataflow visualization systems can be extended to multi-user working, by allowing individual dataflow pipelines to interconnect in order to share data and parameters.  This is now an integral feature within IRIS Explorer. 


eviz project

 The e-viz project - in collaboration with the universities of Manchester, Bangor and Swansea - studied advanced environments for enabling visual supercomputing.  Our contribution, led by Jason Wood, focused on building user interfaces for computational steering and on extending skML from gviz, to provide semantics as well as syntax for visualization pipelines.
integrative biology project

Integrative Biology paper presented at UK e-Science All Hands Meeting 2005
 The Integrative Biology project - a collaboration led by University of Oxford and involving a number of other UK universities - is exploring how e-science technologies can help biologists in the study of heart disease and cancer tumour growth.  Our contribution, led by James Handley and Chris Goodyer, was been in collaboration with Richard Clayton of Sheffield University and Arun Holden of Leeds University, in the context of heart modelling.  We have studied the potential for user interaction in models for cardiac virtual tissue, and novel techniques for displaying multivariate, time-dependent data.

We are now collaborating with NAG and VSNi on a new service-based approach to visualization and analysis in a DTI-funded project called ADVISE.

Visualization Algorithms

Our work aims both to improve the quality of existing algorithms and also to develop novel techniques.  This has been achieved by a talented group of research students over a number of years.  Recent work described below includes improving the quality of isosurfacing; visualization subject to constraints; and novel approaches to multivariate visualization and to volume rendering. 


Accuracy in Isosurfacing

Adriano Lopes and I have studied the behaviour of the trilinear interpolant used in the marching cubes algorithm to determine the surface within a cell.  Our paper in IEEE TVCG gives a complete analysis of the interpolant, and develops a unique topologically correct polygonal representation for the isosurface.  This representation is robust in the sense that it changes continuously as the data changes or the isovalue changes. This means that there are no visual discontinuities when the threshold lies in a neighbourhood of the saddle point value of the trilinear interpolant.
 adriano isosurface

Constrained Visualization

While on sabbatical in New Zealand and California, I extended previous work by my research student, Rafiq Asim, on visualization of data subject to constraints such as positivity.  With Keith Unsworth of Lincoln University in New Zealand, we developed a constrined version of the Shepard family of interpolants.  This enables us to visualize for example rainfall data, where observations are made at scattered locations and we wish to visualize rainfall patterns over a continuous region - while making sure that the  rainfall is always greater than zero.

This is an electronic version of an article published in Computer Graphics Forum. Complete citation information for the final version of the paper, as published in the print edition of Computer Graphics Forum, is available on the Blackwell Synergy online delivery service, accessible via the journal's website at http://www.blackwellpublishing.com/journal.asp?ref=0167-7055 or http://www.blackwell-synergy.com.

 constrained shepard

Multidimensional and Multivariate Visualization

Selan dos Santos and I have sought to unify the visualization of multidimensional (function of many variables) and multivariate (data tables with multiple columns) data.  The Hyperscribe tool guides a user through a sequence of projections in a continuous manner.   This work was presented at Eurographics-IEEE TCVG Symposium on Visualization in 2002, and later published in Computers and Graphics (Vol 28, 2004).

The multivariate visualization research is continuing in the EU-funded VOTech project which is part of the wider European Virtual Observatory (Euro-VR).  Richard Holbrey is looking at the visualization of very large multivariate datsets that occur in astronomy.  Our work is in collaboration with Edinburgh and Portsmouth.

 multivariate vis Selan

Focus and Context Volume Rendering

My research student, Marcelo Cohen, is developing a novel focus and context approach to volume rendering, that can be efficiently implemented on GPUs.  The work is being done in collaboration with Nick Phillips, consultant neurosurgeon at Leeds General Infirmary. 
focus and context - marcelo




 


Ken Brodlie
June 2008