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C-correction of optical satellite data over alpine vegetation areas : a comparison of sampling strategies for determining the empirical c-parameter

Reese, Heather and Olsson, Håkan (2011). C-correction of optical satellite data over alpine vegetation areas : a comparison of sampling strategies for determining the empirical c-parameter. Remote sensing of environment. 115:6, 1387-1400
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Official URL: http://dx.doi.org/10.1016/j.rse.2011.01.019

Abstract

Semi-empirical topographic normalization methods (e.g., C-correction) have been widely used to correct illumination differences in optical satellite data. The objective of this study was to examine the precision and accuracy of the C-correction’s empirical parameter, c, as a function of the sample from which it was derived. Three sampling methods were compared: a random sample, a sample stratified on north and south aspects, and a sample stratified by cosine of the solar incidence angle, i. In the latter, power allocation was used to determine the quantity of observations for each stratum. Four overlapping satellite images were used (two Landsat 5 TM and two SPOT 5 HRG) with different acquisition dates and large solar zenith angles over an alpine region in Sweden. The sample stratified by cosine of i produced c with the highest precision from repeated trials and had coefficients of determination (R2) twice as high as those from the other sampling methods. Use of power allocation in the cosine of i stratified sample enabled better representation of spectral variability; this was particularly important for the NIR band where the outcome of c differed according to sampling method. Evaluations using t-tests and classification accuracy showed that c derived from the cosine of i stratified sample correctly normalized a larger percentage of the evaluation data. The distribution of cosine of i in the study area, the spectral variability and vegetation types exert influences to consider when sampling to derive c. Although sampling was restricted to alpine vegetation only, some vegetation classes may have benefitted from separate c-parameter calculation. In general, dry alpine heath and alpine grass heath had relatively higher c-parameters, mesic alpine heath was slightly lower, and alpine willow and alpine meadow had lower c-parameters for the near-infrared band. The cosine of i stratified sampling method using power allocation may be useful for calculation of c for vegetation conditions other than those presented here, as well as for other empirical parameters (e.g., Minnaert k).

Authors/Creators:Reese, Heather and Olsson, Håkan
Title:C-correction of optical satellite data over alpine vegetation areas : a comparison of sampling strategies for determining the empirical c-parameter
Series/Journal:Remote sensing of environment (0034-4257)
Year of publishing :2011
Volume:115
Number:6
Page range:1387-1400
Publisher:Elsevier
ISSN:0034-4257
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Accepted version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Other Earth and Related Environmental Sciences
(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 207 Environmental Engineering > Remote Sensing
Keywords:Topographic normalization, C-correction, Satellite data, Cosine of i, Stratified sample, Alpine vegetation, Mountain
URN:NBN:urn:nbn:se:slu:epsilon-e-245
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-245
Additional ID:
Type of IDID
DOI10.1016/j.rse.2011.01.019
ID Code:8353
Department:(S) > Dept. of Forest Resource Management
(NL, NJ) > Dept. of Forest Resource Management
External funders:Swedish National Space Board
Deposited By: Heather Reese
Deposited On:01 Nov 2011 14:19
Metadata Last Modified:02 Dec 2014 10:47

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