For environmental noise models it is sometimes necessary to present contours over a very large area, many square km’s. From a modelling perspective it is necessary to have enough calculation points to provide smooth contours and account for features of the modelling domain. PEN3D has an object called a calculation box and these have four corners and the potential to have an internal mesh of up to 20by20. However, sometimes it is preferable to develop mesh based on individual objects. In this example a single calculation box is duplicated to a rectangular array of 10by10 calculation boxes.