areaEstimator {DIGSS}

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)

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.

Value

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

Examples

 #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)