Protected Areas from Space Map Browser with Fast Visualization and Analytical Operations on the Fly. Characterizing Statistical Uncertainties and Balancing Them with Visual Perception

Abstract

Despite huge progress in applying Earth Observation (EO) satellite data to protected areas, managers still lack the right tools or skills to analyze the data and extract the necessary knowledge. In this paper a set of EO products are organized in a visualization and analysis map browser that lowers usage barriers and provides functionalities comparable to raster-based GIS. Normally, web map servers provide maps as pictorial representations at screen resolution. The proposal is to use binary arrays with actual values, empowering the JavaScript web client to operate with the data in many ways. Thanks to this approach, the user can analyze big data by performing queries and spatial filters, changing image contrast or color palettes or creating histograms, time series profiles and complex calculations. Since the analysis is made at screen resolution, it minimizes bandwidth while maintaining visual quality. The paper explores the limitations of the approach and quantifies the statistical validity of some resampling methods that provide different visual perceptions. The results demonstrate that the methods known for having good visual perception, the mode for categorical values and the median for continuous values, have admissible statistical uncertainties.