which are the efficient estimation of geometric correction model parameters and
the efficient prediction of the spatial distribution of residuals. These
two purposes are balanced by minimizing the universal kriging prediction
error variance. Brus and Heuvelink (2007) showed that the
universal kriging variance incorporates both the estimation error
variance of the trend and the prediction error variance of the residual.
After minimizing the mean (or sum) of the universal kriging
variance for the entire image, one automatically obtains the right
balance between optimization of the sample pattern in geographic
and feature spaces. From Figs. 6 and 7, it was demonstrated that
the UKMS design, which considered the spatial autocovariance of
regression residuals, was efficient to estimate the parameters of
geometric correction models. Hence, UKMS performs best in both
simulation and actual-image geometric correction experiments.
As in the UKMS GCPs optimization, the quality measure of MUKV
does not depend on the data values themselves but merely on the
spatial pattern of the predictors and the covariance structure of the
residuals. This allows us to compute the MUKV before collecting
the GCPs coordinates. However, the UKMS needs the variogram of
regression residuals to calculate the covariance of samples and predictors
before samples optimization. In this paper, the variogram
was provided by the SCS geometric correction. Therefore, it needs
to collect GCPs for twice: the first time is to collect the GCPs for
SCS geometric correction which in order to obtain the regression
form and regression residual variogram; the second time is to collect
GCPs for UKMS geometric correction based on the results of
SCS. As a result, this method becomes less efficient, even though
UKMS achieves the most accurate geometric correction. Besides
this, the variogram of regression residuals always contains uncertainty,
which will propagate into UKMS optimization and affect
the GCP configuration. Hence, dealing with the situation that no
prior variogram is known or the variogram has uncertainty is a
key problem in UKMS optimization. Diggle and Ribeiro (2007) provided
a way to solve this problem through utilizing a model-based
geostatistical approach. In this approach, the residual variogram
can be modeled from expert judgment or empirical experience.
Then one treats the variogram as being uncertain and estimates its
parameters using a Bayesian approach (Diggle and Lophaven, 2006;
Diggle and Ribeiro, 2007). Therefore, this model-based geostatistical
method can be adopted in the GCPs spatial pattern optimization
when no variogram is known or variogram has uncertainty.
which are the efficient estimation of geometric correction model parameters andthe efficient prediction of the spatial distribution of residuals. Thesetwo purposes are balanced by minimizing the universal kriging predictionerror variance. Brus and Heuvelink (2007) showed that theuniversal kriging variance incorporates both the estimation errorvariance of the trend and the prediction error variance of the residual.After minimizing the mean (or sum) of the universal krigingvariance for the entire image, one automatically obtains the rightbalance between optimization of the sample pattern in geographicand feature spaces. From Figs. 6 and 7, it was demonstrated thatthe UKMS design, which considered the spatial autocovariance ofregression residuals, was efficient to estimate the parameters ofgeometric correction models. Hence, UKMS performs best in bothsimulation and actual-image geometric correction experiments.As in the UKMS GCPs optimization, the quality measure of MUKVdoes not depend on the data values themselves but merely on thespatial pattern of the predictors and the covariance structure of theresiduals. This allows us to compute the MUKV before collectingthe GCPs coordinates. However, the UKMS needs the variogram ofregression residuals to calculate the covariance of samples and predictorsbefore samples optimization. In this paper, the variogramwas provided by the SCS geometric correction. Therefore, it needsto collect GCPs for twice: the first time is to collect the GCPs forSCS geometric correction which in order to obtain the regressionform and regression residual variogram; the second time is to collectGCPs for UKMS geometric correction based on the results ofSCS. As a result, this method becomes less efficient, even thoughUKMS achieves the most accurate geometric correction. Besidesthis, the variogram of regression residuals always contains uncertainty,which will propagate into UKMS optimization and affectthe GCP configuration. Hence, dealing with the situation that noprior variogram is known or the variogram has uncertainty is akey problem in UKMS optimization. Diggle and Ribeiro (2007) provideda way to solve this problem through utilizing a model-basedgeostatistical approach. In this approach, the residual variogramcan be modeled from expert judgment or empirical experience.Then one treats the variogram as being uncertain and estimates itsparameters using a Bayesian approach (Diggle and Lophaven, 2006;Diggle and Ribeiro, 2007). Therefore, this model-based geostatisticalmethod can be adopted in the GCPs spatial pattern optimizationwhen no variogram is known or variogram has uncertainty.
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