Boundaries: when to draw one, when to skip

What the boundary actually does

Cut and fill are integrated only inside the boundary. EOMeasy drapes both surfaces onto a fine grid and sums the height difference cell by cell, and a cell that straddles the boundary is not rounded in or out: it is clipped to its exact intersection and sampled at the clipped centroid. So the boundary is not a rough mask. It decides precisely what counts toward the volume.

When to supply one

• You already have one. CAD surfaces usually come with a boundary string. Export it alongside the surfaces and EOMeasy uses it directly.
• You want the same scope every month. A fixed pit, stage or bench outline means this month's movement is measured over exactly the same footprint as last month's, so the running total is like for like.
• The survey covers more than the area that moved. If a flight or scan captured ground beyond the work, a boundary trims the measurement back to the part you care about.

When you can skip it

Point clouds usually arrive without a boundary string. Leave the Boundary field blank and EOMeasy measures over the area both surveys cover, the overlapping surveyed footprint, and notes on the report that the boundary was auto-derived.

This works best when you surveyed, or trimmed, only the area that actually moved, because then the overlap is your area of interest. The simplest drone workflow is to trim each cloud to the area of interest in your processing software and skip the boundary entirely.

File formats

• DXF: one or more closed polylines. This is what the export macros write and what your CAD package produces. A DXF can hold several rings, an outer boundary plus inner ones, so a boundary with a hole in the middle (an island of untouched ground, say) measures correctly.
• CSV: a list of boundary points, for when you do not have a CAD string. Same X, Y, Z order as a point file. A CSV is a single ring, so if you need a hole, use a DXF with an outer polyline and an inner one.