Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Measurement error in reflectance data and its implcations for regularizing the variogram
AU - Atkinson, Peter M.
AU - Dunn, R.
AU - Harrison, A. R.
PY - 1996
Y1 - 1996
N2 - Measurement error is an important component of variation in most measured variables and also, therefore, in the sample variogram of field-based reflectance. The variogram of the underlying variation in reflectance is regularized and, therefore, must be continuous through the origin. The variogram of measurement error in reflectance, however, is unlikely to pass continuously through the origin. Therefore, the sample semivariance at a lag of just grealer than zeroy v(0++ ) is likely to be some positive value due solely to the error in measuring reflectance. We recommend that where possible y v(0++ ) should be computed by repeated measurement of reflectance al the same location, x, and over the same support, v. If repeated measurement is not possible then in certain circumstances the nugget variance of the variogram model may be used to estimate measurement error in the sample variogram denotedy v ME, IF y v is not estimated and measurement error is not separated from the underlying variation then geostatistical techniques that depend on yv( h) and which are currently being applied in remote sensing may be affected. We demonstrate these ideas with a simple example involving regularizing the variogram of the Normalized Difference Vegetation Index (NDVI) of a field of pasture measured with a field radiometer.
AB - Measurement error is an important component of variation in most measured variables and also, therefore, in the sample variogram of field-based reflectance. The variogram of the underlying variation in reflectance is regularized and, therefore, must be continuous through the origin. The variogram of measurement error in reflectance, however, is unlikely to pass continuously through the origin. Therefore, the sample semivariance at a lag of just grealer than zeroy v(0++ ) is likely to be some positive value due solely to the error in measuring reflectance. We recommend that where possible y v(0++ ) should be computed by repeated measurement of reflectance al the same location, x, and over the same support, v. If repeated measurement is not possible then in certain circumstances the nugget variance of the variogram model may be used to estimate measurement error in the sample variogram denotedy v ME, IF y v is not estimated and measurement error is not separated from the underlying variation then geostatistical techniques that depend on yv( h) and which are currently being applied in remote sensing may be affected. We demonstrate these ideas with a simple example involving regularizing the variogram of the Normalized Difference Vegetation Index (NDVI) of a field of pasture measured with a field radiometer.
U2 - 10.1080/01431169608949181
DO - 10.1080/01431169608949181
M3 - Journal article
VL - 17
SP - 3735
EP - 3750
JO - International Journal of Remote Sensing
JF - International Journal of Remote Sensing
SN - 0143-1161
IS - 18
ER -