Adding mesh zones to represent changes in mesh resolution

Step-by-step guide

Mesh zone objects are used as part of the mesh generation process to vary the mesh resolution or to define zones in which a ground level modification is required. Often, they are used to represent buildings or roads, or to enhance areas of interest.

In this example, a mesh zone polygon is already created to represent roads, and properties are adjusted to increase mesh resolution and modify element levels.

To increase the mesh resolution from the default 2D zone values:

1. From the Windows toolbar, Grid windows drop-down, select New polygons window.

2. In the grid window, switch to the Mesh zone tab.
3. Click the Maximum triangle area (m2) column heading to highlight the column.
4. Right-click the column and select Current cell(s) Value Set > Set new value(s) for cell(s).

5. In the New Cell Value popup, set the new value to 25.
6. Enable Override 2D zone minimum element area settings for all rows.
7. Set the Minimum element area (m2) to 5 for all rows.

It is also common in some applications to adjust the ground level using mesh polygons—for example, to better define the roads as a flow route in surface water modelling applications. Note that this only needs to be undertaken where the road channel is not sufficiently represented in the ground model. With the resolution of modern ground models now typically 0.5m or lower, this step is often no longer necessary.

To lower the elements:

8. In the Ground level modification column, set all rows to Raise or lower.
9. Set all values in the Raise by column to -0.125.

10. Re-mesh the 2D zone to include these changes.

When loaded, the mesh polygon now has an increased density of mesh elements in the GeoPlan along the roads.

11. From the Windows toolbar, click New 3D network window to see that the element levels have also been adjusted.