Centre de documentation
scientifique

Effects of spatial aggregation approaches on classified satellite imagery / H.S. He in International journal of geographical information science IJGIS, vol 16 n° 1 (january 2002)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 16 n° 1 (january 2002) . - pp 93 - 109 Titre : Effects of spatial aggregation approaches on classified satellite imagery Type de document : Article/Communication Auteurs : H.S. He, Auteur ; S.J. Ventura, Auteur ; D.J. Mladenoff, Auteur Année de publication : 2002 Article en page(s) : pp 93 - 109 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] agrégation spatiale [Termes IGN] classification [Termes IGN] image Landsat-TM Résumé : (Auteur) Spatial aggregations of raster data based on the majority rule have been typically used in landscape ecological studies. It is generally acknowledged that (1) dominant classes increase in abundance while minor classes decrease in abundance or even disappear through aggregation processes ; and (2) spatial patterns also change with aggregations. In this paper, we examined an alternative, random rule-based aggregation and its effects on cover type abundance and landscape patterns, in comparison with the majority rule-based aggregation. We aggregated a classified TM imagery (about 1.5 million ha) from 30 m (4231 x 3717 pixels) incrementally to 990m resolution (132 pixels x 116 pixels). Cover type proportion, mean patch size ratio, aggregation index (AI), and fractal dimension (FD) were used to assess the effects of aggregation. To compare landscapes under different resolutions, we assumed that the landscapes were least distorted if ( 1) the cover type proportions and mean patch size ratios among classes were maintained, and (2) all cover types responded in the same way for a given index as aggregation levels increased. For example, distortion is introduced by aggregation if some cover types increase their AI values with increasing aggregation levels while other cover types decrease. Our study indicated that the two spatial aggregation techniques led to different results in cover type proportions and they altered spatial pattern in opposite ways. The majority rule-based aggregations caused distortions of cover type proportions and spatial patterns. Generally, the majority rule-based aggregation filtered out minor classes and produced clumped landscapes. Such landscape representations are relatively easy for interpreting and, therefore, are suitable for land managers to conceptualize spatial patterns of a study region. By contrast, the random rule-based aggregations maintained cover type proportions accurately, but tended to make spatial patterns change toward disaggregation. Overall, the measurements of landscape indices used in this study indicated that the random rule-based aggregation maintains spatial patterning better than the majority rule-based aggregation. Random rule-based aggregations are more suitable for studies in which the accuracy of spatially explicit information is of concern. They can be very useful in scaling data of fine resolution to coarse resolution, while retaining cover type proportions. Numéro de notice : A2002-006 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810110075978 En ligne : https://doi.org/10.1080/13658810110075978 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21923 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-02011	RAB	Revue	Centre de documentation	En réserve L003	Disponible