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Textural ordination based on fourier spectral decomposition: a method to analyze and compare landscape patterns

par Couteron, Pierre ;Barbier, Nicolas Serge ;Gautier, Denis Jean
Référence Landscape ecology, 21, 4, page (555-567)
Publication Publié, 2006-05

Article révisé par les pairs

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Résumé :

We propose an approach to texture characterization and comparison that directly uses the information of digital images of the earth surface without requesting a prior distinction of structural 'patches'. Digital images are partitioned into square 'windows' that define the scale of the analysis and which are submitted to the two-dimensional Fourier transform for extraction of a simplified textural characterization (in terms of coarseness) via the computation of a 'radial' power spectrum. Spectra computed from many images of the same size are systematically compared by means of a principal component analysis (PCA), which provides an ordination along a limited number of coarseness vs. fineness gradients. As an illustration, we applied this approach to digitized panchromatic air photos depicting various types of land cover in a semiarid landscape of northern Cameroon. We performed 'textural ordinations' at several scales by using square windows with sides ranging from 120 m to 1 km. At all scales, we found two coarseness gradients (PCA axes) based on the relative importance in the spectrum of large (> 50 km-1), intermediate (30-50 km-1), small (10-25 km-1) and very small (<10 km-1) spatial frequencies. Textural ordination based on Fourier spectra provides a powerful and consistent framework to identifying prominent scales of landscape patterns and to compare scaling properties across landscapes. © Springer 2006.