Geoscience Reference
In-Depth Information
19
CHAPTER
A Technique for Assessing the Accuracy
of Subpixel Impervious Surface Estimates Derived
from Landsat TM Imagery
S. Taylor Jarnagin, David B. Jennings, and Donald W. Ebert
CONTENTS
19.1 Introduction...........................................................................................................................269
19.2 Methods ................................................................................................................................270
19.2.1 Study Area ................................................................................................................270
19.2.2 Data...........................................................................................................................272
19.2.3 Spatial Processing.....................................................................................................272
19.2.4 Statistical Processing ................................................................................................274
19.3 Results and Discussion.........................................................................................................275
19.4 Conclusions...........................................................................................................................277
19.5 Summary...............................................................................................................................278
Acknowledgments ..........................................................................................................................279
References ......................................................................................................................................279
19.1 INTRODUCTION
An emerging area in remote sensing science is subpixel image processing (Ichoku and Karnieli,
1996). Subpixel algorithms allow the characterization of spatial components at resolutions smaller
than the size of the pixel. Recent studies have shown the general effectiveness of these techniques
(Huguenin, 1994; Huguenin et al., 1997). The importance of subpixel methods is particularly
relevant to the field of impervious surface mapping where the predominance of the “mixed pixel”
in medium-resolution imagery forces the aggregation of urban features such as roadways and
rooftops into general “developed” categories (Civco and Hurd, 1997; Ji and Jensen, 1999; Smith,
2001). The amount of impervious surface in a watershed is a landscape indicator integrating a
number of concurrent interactions that influence a watershed's hydrology, stream chemical quality,
and ecology and has emerged as an important landscape element in the study of nonpoint source
pollution (NPS) (USEPA, 1994). As such, Schueler (1994) proposed that impervious surfaces should
be the single unifying environmental theme for the analysis of urbanizing watersheds. Effectively
extracting the percentage of impervious surface from medium-resolution imagery would provide
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