Models and Methods to Represent and Explore Phenomena on GIS

Abstract

Many models have been developed by experts to compute a specific phenomenon from a set of measures. In France for example the model named Saturne, based on fluid dynamic (CFD), allows to study either the effect of a phenomenon on the environment (such as the pollution on a district) or the effect of the environment on a phenomenon (such as the impact of buildings on the local rising of temperature). These models are of prime importance today. They use and produce geographical information. In this context, we can question the role of GIS and cartography to map phenomena. The first easy diagnostic is that the work flow between measures and the representation of phenomena is sometime weak, even thought all the technology exists today to propose efficient solutions. The other diagnostic is that the representation of phenomena is often limited to a DPM (a digital phenomenon model), inspired by DTM and using DTM format, to overlay the representation of phenomena on the geographical space. But phenomena should be represented in better way: they are not constant in Z, they vary in time, and moreover their impacts depend on the duration and on the subject located in a specific place. In this paper we identify the workflow from the measure to its representation, we identify the necessary information to represent topographical data, a 3D phenomenon (such as noise or chemical pollution) and the effect of phenomena on alive ‘bodies’ (such as a baby, a child, a person working during the night, a person having breathing difficulties, a cat or even a plant). We first propose a data model including the description of phenomena episode, the description of the different ways to represent graphically this phenomenon in quantitative and qualitative ways. Then we propose some graphical solutions that could enrich GIS software to improve our capacity of representing phenomena in 2D or 3D environment. To illustrate our ideas we take the example from the Immanent project in which we were involved.