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OMEGA/Mars Express hyperspectral imagery is an excellent source of data for exploring the surface composition of the planet Mars. Compared to terrestrial hyperspectral imagery, the data are challenging to work with; scene-specific transmission models are lacking, spectral features are shallow making them difficult to detect, and field data for validation is mostly not available. Software is available for calibrating the raw data to radiance-at sensor, but a processing methodology for processing the radiance data to surface reflectance is not straightforward. In this paper, we present a processing methodology for converting OMEGA data from radiance-at-sensor to surface reflectance. To overcome specific issues with OMEGA data, we developed novel methods for determining a per-scene transmittance spectrum, performing an atmospheric correction, and filtering systematic and random noise. The processing methodology produces surface reflectance images, from which single-pixel spectra can be extracted to identify surface features. Consistent with several previous studies, our results indicate the presence on the Martian surface of iron-rich clays. © 2013 Elsevier Ltd.

Geological maps are increasingly published and shared online, whereas tools and services supporting information retrieval and knowledge discovery are underdeveloped. In this study, we developed an ontology of geological time scale by using a RDF (Resource Description Framework) model to represent the ordinal hierarchical structure of the geological time scale and to encode collected annotations of geological time scale concepts. We also developed an animated graphical view of the developed ontology, and functions for interactions between the ontology, the animation and online geological maps published as layers of OGC Web Map Service. The featured functions include automatic annotations for geological time concepts recognized from a geological map, changing layouts in the animation to highlight a concept, showing legend of geological time contents in an online map with the animation, and filtering out and generalizing geological time features in an online map by operating the map legend shown in the animation. We set up a pilot system and carried out a user-survey to test and evaluate the usability and usefulness of the developed ontology, animation and interactive functions. Results of the pilot system and the user-survey demonstrate that our works enhance features of online geological map services and they are helpful for users to understand and to explore geological time contents and features, respectively, of a geological map.