DIGSS (version 1.0.2)

areaEstimator: Area Estimator

Description

Estimate the area of multiple overlapping ellipses

Usage

areaEstimator(sitemap, fieldarea, precision = 1000)

Arguments

sitemap

a matrix with sites per row and columns: site_number, site_area, eccentricity, angle, center.x, center.y, ellipse.a,ellipse.b

fieldarea

vector with dimensions of field surveyed in km: c(x_size,y_size)

precision

how many dots will be projected of field. Total dots equal precision * precision. Default value = 1000 (1 million dots projected)

Value

The rate of points that are inside at least one ellipse divided by all points projected in the area.

Details

This function will estimate the area occupied by sites (ellipses) in a rectangular field, taking into consideration the fact that sites can overlap. It is formatted to be used inside fieldMap().

This function is a cookie-cutter area estimator, given the complexities of calculating the real areas of overlapping ellipses. It projects N x N equally spaced dots in the survey field and calculates the ratio of how many of them fall inside at least one site (ellipse). Using a precision of 1000 x 1000 dots, it approximates area to within 0.1% of real area.

Examples

# NOT RUN {
 #create a matrix with 2 sites randomly located using `fieldMap()`
 site.example<-fieldMap(c(1,1),2,250000,plot=TRUE)

 #define size of field
 field.area<-c(1,1)

 #calculate area
 areaEstimator(site.example$site.frame,field.area)

# }