Spectrally heterogeneous land-use categories cannot be adequately clas
sified from high resolution satellite data, using conventional multisp
ectral classification techniques. In this study, built-up land is extr
acted based on the spectral and the spatial properties of the segments
in a spectrally classified satellite image. Object structures and cla
ssification rules have been implemented in an expert system shell - Ne
xpert Object. The approach has been tested using SPOT multispectral da
ta covering an area south of Stockholm, Sweden, The classification acc
uracy for built-up land improved significantly after the application o
f a few relatively simple rules, based on segment size and on relation
s between segments. The object oriented implementation in Nexpert Obje
ct is flexible but slow, and performance problems were encountered due
to the large number of objects being processed.