Description Usage Arguments Details Value References Examples
Estimates animal density (amongst other parameters) from twoplane
aerial surveys. This conceptualises sighting locations as a
NeymanScott point pattern—estimation is carried out via
fit.ns()
.
1 2 
points 
A vector (or singlecolumn matrix) containing the distance along the transect that each detection was made. 
planes 
An optional vector containing the plane ID (either

d 
The length of the transect flown (in km). 
w 
The distance from the transect to which detection of individuals on the surface is certain. This is equivalent to the halfwidth of the detection zone. 
b 
The distance from the transect to the edge of the area of interest. Conceptually, the distance between the transect and the furthest distance a whale could be on the passing on the first plane and plausibly move into the detection zone by the passing of the second plane. 
l 
The lag between planes (in seconds). 
tau 
Mean divecycle duration (in seconds). 
R 
Truncation distance (see fit.ns). 
edge.correction 
The method used for the correction of edge
effects. Either 
start 
A named vector of starting values for the model parameters. 
bounds 
A list with named components. Each component should be a vector of length two, giving the upper and lower bounds for the named parameter. 
trace 
Logical, if 
This function is simply a wrapper for fit.ns
, and
facilitates the fitting of the model proposed by Stevenson,
Borchers, and Fewster (in prep). This function presents the
parameter D.2D
(twodimensional cetacean density in
cetaceans per square km) rather than D
for enhanced
interpretability.
An R6 reference class object. Extraction of the information held within is best handled by functions coef.nspp, confint.nspp, summary.nspp, and plot.nspp.
Stevenson, B. C., Borchers, D. L., and Fewster, R. M. (in prep) Tracecontrast methods to account for identification uncertainty on aerial surveys of cetacean populations.
1 2  fit < fit.twoplane(points = example.twoplane$points, planes = example.twoplane$planes,
d = 500, w = 0.175, b = 0.5, l = 20, tau = 110, R = 1)

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