If the map data aren't updated or if a new data array isn't passed to the terrain when it reaches the map edges, then the terrain goes on moving as if the current map where repeated on the current axis. The distance between the points is constant on the width and is different from the constant distance between the points on the height. It's defined by 1000 points on its width and 800 points on its height. We use a simplex function from a third party library to set each point altitude. Here, we populate a big Float32Array with successive 3D float coordinates. the distance between each row is quite constant, not necesseraly the same than the distance between each column.the distance between each column is quite constant.for any column i in the map, P.z is lower than P.z, what is lower than P.z, etc.for any row j in the map, P.x is lower than P.x, what is lower than P.x, etc.If we call P the point P at the row j on the map height and at the column i on the map width, this means that : the points must be sorted in ascending order regarding to their coordinates, first on the width, then on the height.the distances between two successive points on the map height must be quite constant.the distances between two successive points on the map width must be quite constant.The dynamic terrain imposes some constraints to the map : It's defined by the number of points on the map width, called mapSubX by the dynamic terrain, and the number of points on the map height, called mapSubZ.

The data map is a simple flat array of successive 3D coordinates (x, y, z) in the World. The first thing we need to create a dynamic terrain is a data map. Some documented examples are here : Getting Started The Data Map

Babylon map