The Removal of Numerical Drift from Scientific Models

Computer programs often behave differently under different compilers or in different computing environments. Relative debugging is a collection of techniques by which these differences are analysed. Differences may arise because of different interpretations of errors in the code, because of bugs in the compilers or because of numerical drift, and all of these were observed in the present study. Numerical drift arises when small and acceptable differences in values computed by different systems are integrated, so that the results drift apart. This is well understood and need not degrade the validity of the program results. Coding errors and compiler bugs may degrade the results and should be removed. This paper describes a technique for the comparison of two program runs which removes numerical drift and therefore exposes coding and compiler errors. The procedure is highly automated and requires very little intervention by the user. The technique is applied to the Weather Research and Forecasting model, the most widely used weather and climate modelling code.Comment: 12 page

StructureMorph: Creating Scholarly 3D Models for a Convergent, Digital Publishing Environment

Background:  The StructureMorph project rests on the premise that future publishing platforms will converge multiple applications, such as geographic information systems (GIS) and game engines, and multiple paradigms of computing, such as desktop computing and high-performance computing. Convergent platforms will also present design challenges for scholars.Analysis:  In this contribution, one response to these challenges is presented: the Complex Object. Complex Objects are 4D models that alter their shape and surface appearance in response to user interaction, and changes in world time. They also to mimic the behaviours of 2D polygons as configured in geographic information systems, graphically linking attribute data with spatial locales.Conclusion and implications:  This article discusses the concept of the Complex Object and describes the software and workflow devised to support its creation

The Compilation of 2D and 3D Dynamic Visualizations

3D modelling and visualization are rapidly developing in power and application. Unfortunately they are also developing in complexity of use. They require considerable practice and skill in order to model and visualize successfully. This paper presents modelling and visualization strategies and tools based on textual descriptions of models and visualizations. The principles of compilation used in coding for many decades are applied to modelling and visualization. This results in tools able to model and visualize many types of dynamic object such as ships and locomotives that can be used successfully by non-expert users who have knowledge of the objects being modelled. The tools have been used in local primary schools since 2007

Kiddy CAD: A Child Friendly Parametric Approach for 3D Modeling Software

3D models are increasingly used to visualize objects for presentation in schools. Children are sophisticated consumers of 3D worlds and engaging creatively with ICT in the classroom is recognized as beneficial to developing multiple intelligences in children. Historically, the creation of 3D models by children has, however, been considered too difficult a process to master. This paper describes the development of a CAD tool, Church Builder, designed for use by children, which is fast, fun and easy to learn and has minimal system requirements. The tool treats the underlying data of the 3D models as a tree structure of nodes, consisting of parameterized representations of the components of the objects being modeled. The tool automatically generates graphics primitives that enable the visualization of and interaction with the object, allowing children to rapidly build sophisticated model church structures