kirra-docs

Surface Intersection

Draws the line where two surfaces cross — a design against topography, a pit shell against the current pickup, a bench floor against a wall. The result is a set of KAD lines or polygons you can offset, export or use as a clip boundary.

Surface Intersection dialog

Intersect two surfaces

  1. Click Surface Intersection on the Surface toolbar. The Surface Intersection dialog opens.
  2. Choose Surface A and Surface B from the lists, or click the target button beside each and click the surface in the 3D view. The picked surface flashes green.
  3. Set the fields (below).
  4. Click Compute. A progress window reports each step and closes itself when done.

You need at least two loaded surfaces. With fewer, Kirra says “At least 2 loaded surfaces are required for intersection.” The lists include hidden surfaces; the pick button only finds visible ones.

The fields

Field Default What it does
Vertex Spacing (m) 1.0 Simplifies the result: vertices closer than this are dropped. 0 keeps every vertex
Close Polygons On Closes each result into a polygon. Off gives open lines
Color Yellow Colour of the result
Line Width 3 Line width of the result (1–10)
Sub-layer Name Intersections The sub-layer the result is filed in

The dialog remembers your last surfaces and settings in this browser.

What you get

One KAD entity per intersection line, named after both surfaces — for example Topo_PitDesign_Intersect_a1b2. They are filed in the Analysis layer, under the Sub-layer Name — or in your active layer, if you have chosen one. The whole set is one undo step.

Troubleshooting

Symptom Cause Fix
“Surface A and Surface B must be different.” The same surface is in both lists Choose a second surface
“No intersections found between the selected surfaces.” The surfaces do not touch Check them together in 3D
“Intersections found but all polylines were too short after simplification.” Vertex Spacing (m) is larger than the pieces Lower it, or set it to 0
A closed polygon cuts across where you expected an open line Close Polygons is on Turn it off for crest or toe lines that run off the edge

Other ways to use it

Method Result
Target button, then click in 3D Picks a surface without searching the list
Vertex Spacing (m) = 0 Keeps every crossing point, for the most exact line
Close Polygons off Open strings, for crest and toe lines