A Classic Problem

In many cases, you have given outer boundaries for cutting and filling. This can be, for example, property boundaries that provide this limitation.

In the examples so far, we have constructed the excavation's main surface and placed cutting and filling surfaces on the main surface's boundary contour.

Building excavation with filling and cutting from the main surface's boundary contour

A problem is that we do not know where the cutting and filling surfaces hit the terrain when we create this contour.

In this example, you have a reverse problem. You must find the boundary contour with a given outer boundary for the excavation's total extent.

Solution Method

There is a method you can use to solve such problems. First, you must create a new drawing (for example Draft) in your project. In this, you then create an application layer with future level and use a helper excavation to find the boundary contour for the main surface.

In the helper excavation, you enter the outer boundary that is given and calculate cutting and filling surfaces against future levels. The direction of the outer boundary must be clockwise so that cutting and filling surfaces go inward. You must also swap the values in the parameters for cutting and filling.

When the direction for the boundary contour goes clockwise, cutting and filling surfaces go inward

When this is done, you can copy the calculated boundary contour (the Copy outer line function) in the helper excavation. Then switch to the drawing with the excavation and paste it in. Then set cutting and filling surfaces on this boundary contour.

The building excavation's outer boundary is within the property boundary

Note

The excavation's outer boundary must have elevations at terrain level. You can, for example, use the Snap to layer function if the line does not have correct elevations.