Working Towards a Landscape Information System

Key words: Landscape, Systematic Approach, Image Bank, Content-Based Image Retrieval Indexing, Temporality, Spatial Continuum, Image Perception, Colour Analysis

The systematic analysis of landscape through photographs taken from the ground, as practised by the geographers of Besanon, rests on the development of banks of landscape images collected by sampling the area. This sampling differs according to the size and scale of analysis, the geographic structure of the area considered, and depends on whether a surface or a linear entity is to be sampled. These investigations allow both spatial and temporal study of the landscape.

Concurrently, current research into computational vision shows a need for software which allows one to collect various perceptual features and their characteristics as these appear to someone observing a natural scene. So, one seeks to study factors involved in the delineation of regions of perceptually significant images and, more generally, the interactions between elements that are juxtaposed, superposed, and function in an emergent dynamic.

Whatever the scale of the study, large collections of photos are gathered (hundreds to thousands): Their analysis and their restitution pose some problems that computer science and multimedia can resolve.

In passing from the rough corpus of photos to a bank of analysed and indexed images, we are constructing an integrated computational tool.

It has two potential uses:

• To restore spatial continuum to the landscape by managing spatially and angularly oriented mosaics of images. In addition to on-demand visualisation, such a tool allows us to develop transects, cross-sections, and spatial partitions linked to landscape parameters. It also allows a dynamic approach by offering the possibility of simulated walks through the landscape and perceptive courses, and of allowing cognitive inquiries, indeed virtual trips. A unit of structural analysis of the image allows us to interpret each image according to grounds, categories of objects, visual features, triptych hue-saturation-luminance, and semantic aspects. Data collected in this manner is analysed statistically and cartographically.
• To manage some multi-temporal series of landscape images and to work on the different temporalities of the landscape. Three temporal scales are considered: yearly cycles (local and global change), seasonal cycles (landscape phenology), and daily cycles (linked to the apparent movement) of the sun and to the instantaneous climatic ambience.

• the unit of data acquisition for the analysis of the images;
• the structure of the spatial image bank; and
• the multi-temporal approach using an automatic analysis of light and colour.