Notion of a 3-D grid inside GOCAD

In the GOCAD software, the class of object GRID3 is aimed at building 3-D grids. As is shown in Figure 2, the 3-D grid is defined by its origin, three vectors $\vec{U}$, $\vec{V}$, $\vec{W}$ giving the three directions of the axes of the grid, and three integer values nu, nv, nw corresponding to the sampling on each of the axes.

When a new grid is created, the value at each node of the grid is set to an initial value. The user has to update the values inside the grid with respect to a given model.