plugincvc | R Documentation |
This function computes the plug-in moment covariance estimate of a stationary RACS from a binary map.
For a stationary RACS, \Xi
, the covariance
for a vector v
is the probability of two points separated by a vector v
are covered by \Xi
C(v) = P(\{x,x+v\}\subseteq \Xi).
plugincvc(xi, obswin = NULL, setcov_boundarythresh = NULL)
xi |
An observation of a RACS of interest as a full binary map (as an |
obswin |
If |
setcov_boundarythresh |
To avoid instabilities caused by dividing by very small quantities, if the set covariance of the observation window
is smaller than |
The plug-in moment covariance estimator is (Serra, 1982)
\hat{C}(v) = \frac{\gamma_{W\cap X}(v)}{\gamma_W(v)}
where \gamma_{W}(v)
is the set covariance of the observation window W
and \gamma_{W\cap X}(v)
is the set covariance of the foreground within W
.
plugincvc
uses Fourier transforms to calculate the set covariance (using the setcov
of the foreground and observation window.
Vectors with small \gamma_W(v)
are eliminated using setcov_boundarythresh
as division by small values is numerically unstable.
A SpatStat im
object containing the estimated covariance.
Kassel Liam Hingee
Serra, J.P. (1982) Image Analysis and Mathematical Morphology. London; New York: Academic Press.
xi <- as.im(heather$coarse, na.replace = 0)
covar <- plugincvc(xi)
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