getIntersectionForRoughnessAgainstLengthscale get the intersection between tangente and plateau
getIntersectionForRoughnessAgainstLengthscale(
AFMImageAnalyser,
minValue,
maxValue,
second_slope = FALSE
)an AFMImageAnalyser to get Roughness against lenghtscale calculation
index of the lowest point to be used for the tangent
index of the highest point to be used for the tangent
a boolean to manage first or second slope in the roughness against lenghtscale curve