Mapping of Submerged Aquatic Vegetation in Rivers From Very High Resolution Image Data, Using Object Based Image Analysis Combined with Expert Knowledge

The use of remote sensing for monitoring of submerged aquatic vegetation (SAV) in fluvial environments has been limited by the spatial and spectral resolution of available image data. The absorption of light in water also complicates the use of common image analysis methods. This paper presents the results of a study that uses very high resolution (VHR) image data, collected with a Near Infrared sensitive DSLR camera, to map the distribution of SAV species for three sites along the Desselse Nete, a lowland river in Flanders, Belgium. Plant species, including Ranunculus aquatilis L., Callitriche obtusangula Le Gall, Potamogeton natans L., Sparganium emersum L. and Potamogeton crispus L., were classified from the data using Object-Based Image Analysis (OBIA) and expert knowledge. A classification rule set based on a combination of both spectral and structural image variation (e.g. texture and shape) was developed for images from two sites. A comparison of the classifications with manually delineated ground truth maps resulted for both sites in 61% overall accuracy. Application of the rule set to a third validation image, resulted in 53% overall accuracy. These consistent results show promise for species level mapping in such biodiverse environments, but also prompt a discussion on assessment of classification accuracy.

Generative Divergent Analysis as a Model for Reflection Illustrated with Reference to an Early-years Reception Class and Wicker Settee

Generative divergent analysis (GDA) is a creative additive approach to raising insignificant details of experience to significance. A schematic view of the model highlights use of evocative objects as starting point for ‘turning towards’, ‘turning away’ and ‘being-in-relation-to’ as part of an ongoing burgeoning of experience.The model is exemplified by focusing on a wicker settee as an evocative object that was noticed in an early-years reception class. Revisiting the object generated several speculative ideas relating to the hidden curriculum and energies of childhood. Poetry and song were used during the revisiting in order to develop a more direct experience in addition to the more contemplative awareness that was evoked during the first encounters. As an additive process the outcome of GDA takes the form of unfinished resources for thinking.