AUTOMATIC BREAKLINE EXTRACTION
STREAM finds the slope faces on your site by itself and adds the crest and toe of each one as a 3D line on the map. You do not have to select an area — leave it empty and the whole survey is scanned. It is the work that takes hours of tracing in CAD, reduced to one command.
A breakline is a line along which the terrain changes slope abruptly — the top and bottom edges of a cut face, the shoulder of a road, the lip of a bench. Surfaces built without them round off exactly where the ground is sharpest, and the volume you compute from that surface is wrong.
On a bench, the crest is the upper break where the flat bench meets the face, and the toe is the lower break where the face meets the bench below. Together they define the face: loft between a crest and its matching toe and you have the slope surface itself.
All slope faces in the selection — or across the whole survey if you select nothing — are found and traced in a single run. Crest and toe are written to separate layers, and the layer name is also the DXF layer name, so the drawing arrives in CAD already sorted.
At each node the bench plane and the face plane are fitted separately and intersected — the same way an engineer sets a crest out in the field. Without that step the line falls where the slope first crosses the threshold, roughly a metre up the face rather than on the edge.
A ramp cutting through the pit joins every bench into one connected boundary, and the longest line out of it is really the road edge. Those are written to their own ramp layers instead of being merged with bench lines — otherwise a loft between crest and toe would treat a road edge as a slope face. The test is longitudinal grade: benches are built level (1–3% for drainage), ramps fall 8–12%.
Smoothing suppresses noise but also rounds a 90° bench corner by its nature, so each corner is rebuilt as the intersection of its two straight legs. On a platform with 30 m sides this pulls the corner error from 2.2 m to 0.85 m and the line from 28 vertices down to 4. Corners that do not exist are not invented: if the turn is not concentrated in a short arc, it is a real curve and is left alone.
Benches are rarely excavated without interruption — a ramp cuts through, waste covers a stretch, a section fails. Split lines are rejoined only when four conditions hold at once: same type, endpoints close, direction continuous and elevations close. The fourth is what stops a lower bench's crest from joining the bench above it. The number of pieces merged is reported.
Numbering follows the slope face rather than the order lines were found, so "Crest 3" and "Toe 3" are the two ends of the same face. Loft between them and you have built the slope surface directly.
Each result is a normal line record: select it, edit a vertex, undo with Ctrl+Z, export it to DXF or CSV. The extraction is a proposal, not a locked output.
Load the DEM or the point cloud you surveyed. The extraction runs on the elevation surface.
Draw an area to limit the run to one part of the pit, or leave it unselected to scan everything. A smaller area is computed at a finer cell size, down to 10 cm; the whole site coarsens automatically.
The slope threshold defines what counts as a face. The default is 60% and the value used is written into the result, so the definition travels with the output.
The lines land on the map in their own layers. Check what the run tells you: the cell size actually used, how many pieces were merged, whether any terrain fell below the threshold and how large it was.
If a face boundary forks — a hole, a narrow neck — those lines are flagged for you to inspect. Nothing is dropped silently.
Fix any vertex that needs it, then loft between a crest and its matching toe to build the slope surface, or send the layers to DXF for the drawing set.
No. With nothing selected the whole survey is scanned. Selecting an area limits the run and buys resolution: the smaller the area, the finer the cell size used, down to 10 cm. The cell size that was actually used is reported, and the positional accuracy of a line can never be better than it.
No, and this matters. It is a slope-break extraction, not a geological interpretation — a natural hillside steeper than the threshold is traced exactly like a cut face. The threshold is a definition rather than a discovery, which is why the value used is written into the result.
The line sits on the outer break of the berm, because the true bench crest is behind it and cannot be seen from the surface at all. Measured on a 2.5 m berm, the line falls about 1.6 m inside the true crest. The lines are not broken up — they shift systematically — so allow for it when setting out.
The noise-smoothing radius is larger than half your bench width, so the flat signature of each bench is being erased and the pit collapses into one steep face. Measured on 3 m benches: a 2 m radius produced 1 line where there should have been 16; the same site at 1 m produced 16 crests and 16 toes. STREAM warns you when this happens and the radius can be lowered from the options window.
Ramp and road edges are separated into their own layers rather than merged with bench lines. The criterion is longitudinal grade — benches are built roughly level for drainage while ramps fall 8–12% — so a road edge is not mistaken for a slope face when you loft.
Yes, and you should treat them that way. Every extracted line is an ordinary line record: selectable, vertex-editable, undoable and exportable. The extraction gives you a proposal that is already on the break; the engineering judgement stays yours.
Yes. Crest and toe are numbered by slope face rather than by discovery order, so "Crest 3" and "Toe 3" are the two edges of the same face. Loft between them and the face is built.
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