4
ON THE ISSUE OF SCALE IN URBAN
REMOTE SENSING
QIHAO WENG
4.1 INTRODUCTION
In a review article on the scale and resolution effects in remote sensing and geographic
information systems (GISs), Cao and Lam (1997) raised two questions: (1) “how large
an area should be covered to appropriately examine a geographic phenomenon, or at
what scale and resolution should the study be conducted” and (2) “whether or not the
results of the study at one scale can be extrapolated to other scales.” These two
questions are still valid today for most studies in urban remote sensing.
A key to scale- and resolution-related issues is to develop proper methods for
“determining the most appropriate scale and resolution of study and assessing the
effects of scale and resolution” (Cao and Lam, 1997). The majority of research efforts
in urban remote sensing over the past decade have been made for mapping urban
landscapes at various scales and on the spatial resolution requirements of such
mapping (Weng, 2012). Previous models, methods, and image analysis algorithms in
urban remote sensing have been largely developed for the imagery of medium
resolution (10–100 m). In contrast, there is less interest in spectral and geometric
properties of urban features. The advent of high-spatial-resolution satellite images and
increased interests in spaceborne hyperspectral images, Lidar sensing, and their
synergy with existing technologies are stimulating new research ideas in urban remote
sensing and are driving the future research trends with new models and algorithms.
The urban remote sensing community will need to address how these new frontiers in
Earth observation technology since 1999 and advances in remote sensing imaging
science—such as object-oriented image analysis, data fusion, and artificial neural
61
Scale Issues in Remote Sensing, First Edition. Edited by Qihao Weng.
2014 John Wiley & Sons, Inc. Published 2014 by John Wiley & Sons, Inc.
ON THE ISSUE OF SCALE IN URBAN
REMOTE SENSING
QIHAO WENG
4.1 INTRODUCTION
In a review article on the scale and resolution effects in remote sensing and geographic
information systems (GISs), Cao and Lam (1997) raised two questions: (1) “how large
an area should be covered to appropriately examine a geographic phenomenon, or at
what scale and resolution should the study be conducted” and (2) “whether or not the
results of the study at one scale can be extrapolated to other scales.” These two
questions are still valid today for most studies in urban remote sensing.
A key to scale- and resolution-related issues is to develop proper methods for
“determining the most appropriate scale and resolution of study and assessing the
effects of scale and resolution” (Cao and Lam, 1997). The majority of research efforts
in urban remote sensing over the past decade have been made for mapping urban
landscapes at various scales and on the spatial resolution requirements of such
mapping (Weng, 2012). Previous models, methods, and image analysis algorithms in
urban remote sensing have been largely developed for the imagery of medium
resolution (10–100 m). In contrast, there is less interest in spectral and geometric
properties of urban features. The advent of high-spatial-resolution satellite images and
increased interests in spaceborne hyperspectral images, Lidar sensing, and their
synergy with existing technologies are stimulating new research ideas in urban remote
sensing and are driving the future research trends with new models and algorithms.
The urban remote sensing community will need to address how these new frontiers in
Earth observation technology since 1999 and advances in remote sensing imaging
science—such as object-oriented image analysis, data fusion, and artificial neural
61
Scale Issues in Remote Sensing, First Edition. Edited by Qihao Weng.
2014 John Wiley & Sons, Inc. Published 2014 by John Wiley & Sons, Inc.