The technique of sampling used in the ecology for determining how much plants or animals are in a given fixed region. A set of randomly placed lines or points is recognized and the distances calculated to those objects detected by the travelling the line or the surveying the points.
As the certain object is detected, its distance to the randomly chosen line or the point is calculated and on completion n objects have been detected and their connected distances recorded. Under certain suppositions unbiased estimates of density can be made from these distance data.