In the Location module, cross section end areas (and therefore volumes) are calculated using a layer merging process which simulates the construction sequence. With fixed cross sections, you control the shape and order of the layers, so it is important to understand this process.
Step 1 Layer 2 is compared with layer 1 (usually topo) and the difference is calculated; this defines the cut and fill areas for layer 2 (in this case stripping).
Step 2 Layers 1 and 2 are merged to create a new merged surface (in this case the stripped surface).
Step 3 The merged surface replaces layer 1, layer 3 replaces layer 2 and the two steps above are repeated.
Step 4 Repeat until all layers are processed.
The figure below shows the progression of the merged surface.
