TOWARDS A PROBLEM OF VISUAL REPRESENTATIONS TO EXPRESS UNCERTAINTY IN TEMPORAL GEODATA

Ms. Li¹, Prof. Kraak¹, Prof. Ma²

1 - ITC, department of Geo-information processing, Enschede, the Netherlands

2 - Resource Department, Chang an University, Xi an, China

xia@itc.nl

In the analysis of geo-processes of change the temporal component of geographic data plays an underestimated role, since it does potentially affect the outcome of the analysis process or influences the interpretation of the resulting data. This is mainly due to the lack of understanding and the complexity of the time component.

In the analysis of for instance the regional climate the data categories used can each have a different time stamp, and be of a different temporal resolution. Temperature data could be gathered over the last 30 years with an increasing accuracy but in a non-homogeneous spatial pattern, satellite data will have a homogeneous spatial distribution, but has improved in resolution and the number of bands over time. For other data required one might still rely on written records with irregular intervals. How to work with time series that are so erratic in nature? And how to evaluate the outcome of an analysis which has to rely on such a diversity of temporal data?

This paper will suggest a systematic approach to deal with uncertainty in the temporal component of the data. It will be based on the temporal elements as defined in the geographic metadata standards (ISO 19115). Basic concepts, like temporal consistency, temporal accuracy and precision are discussed to analyze the elements of time uncertain in geo-data. The source of the uncertainty, such as collection, processing, updating, and visualization, will be discussed in detail. Based on the above analyses, taxonomy of temporal uncertainty is suggested and will be linked to the existing and new visualization methods to assist the user during the spatial data handling process.