Learn about specifying a zone that encompasses an area in which grading optimisation will occur.
This video demonstrates:
In Grading Optimization, a zone is a defined area of surface polygons that can be specified with constraints. The constraints then apply to the surface triangles within the zone during optimisation.
The key concepts in Grading Optimization involve grading limits. A grading limit zone is one in which its boundary is fixed to the existing ground elevations. When a grading limit zone is placed, no grading happens outside of the zone. However, multiple grading zones may be placed.
Grading zones can use global constraints, customised constraints or no constraints at all. In this example we will start by using the global constraints which are set to 20 per cent. To specify a zone as a grading limit zone, enable the Grading Limit property in the Zone Properties dialog.
You can also use the preconfigured Grading Limit zone tool in the Grading Object Tool Palette.
Here, a warning shows that some of the triangles along the grading limit have a slope of greater than 20 per cent. Because they are along the border of a grading limit zone, an optimisation solution is not feasible. This can be seen in the Convergence Plot dialog as a constant proximity value that no longer moves towards zero.
To attempt to adjust this, we will apply customised slope constraints. Select the zone and select it in the Grading Objects Browser. Select Customised Slope Constraints and relax the Maximum Slope constraint to 33 per cent.
To show slope values on the surface, we can customise colour ranges for the slope theme visualisation. In the Visualisation Settings dialog, expand Advanced Settings. Set the highest range to 33 per cent and red.
To better see the slope, you can hide the zone by disabling the visibility in the Grading Objects Browser. These red areas show where the terrain is greater than 33 per cent.
Now during optimisation, the proximity value does moves toward zero indicating a unique feasible solution.
Learning grading limits will give you greater understanding of the optimisation solutions when other grading objects are utilised.