kirra-docs

Contour Surface

Draws contour lines across a surface at a regular elevation interval. Use them to read a pickup at a glance, to check a design floor, or to export bench and toe strings to CAD.

Surface Contours dialog

Contour a surface

  1. Click Contour Surface on the Surface toolbar. The Surface Contours dialog opens.
  2. Choose the Surface, or click the target button and click the surface in the 3D view. The picked surface flashes green.
  3. Set Contour Interval (m) and where the levels start (below).
  4. Click Generate. The contours are added as KAD lines and Kirra reports how many were made.

With no surfaces loaded, Kirra says “No surfaces loaded. Import a surface (DTM, STR, OBJ) first.” The list includes hidden surfaces.

The fields

Field Default What it does
Contour Interval (m) 5 Vertical distance between contours
Start From Min (up) Where the levels are counted from: Min (up), Max (down), Zero or Custom
Starting Origin (m) The surface’s lowest point The level the interval is counted from. Editable with Custom only
Min Elevation (m) Lowest point, rounded down No contours below this
Max Elevation (m) Highest point, rounded up No contours above this
Vertex Spacing (m) 0 Simplifies the lines: vertices closer than this are dropped. 0 keeps every vertex
Close Polylines Off Closes each contour into a polygon
Color Yellow Colour of the contours
Line Width 2 Line width (1–10)
Sub-layer Name Contours The sub-layer the contours are filed in

Levels are the Starting Origin (m) plus whole multiples of the interval, between the min and max. With Zero and a 2 m interval, contours fall on even RLs — 616, 618, 620 and so on.

The dialog remembers your settings in this browser. Choosing a different surface refills the min and max from that surface.

Tip: To contour your bench RLs exactly, choose Custom, type one bench RL as the Starting Origin (m) and use the bench height as the interval.

What you get

KAD lines — or polygons, with Close Polylines — in the Analysis layer under the Sub-layer Name, or in your active layer if you have chosen one. Each is named after the surface and its RL, for example Pit_Contour_RL640_001_a4zz, so sorting by name groups each level together. The surface itself is not changed. The whole set is one undo step.

The result message lists the count, the elevation range, the interval and the time taken.

Troubleshooting

Symptom Cause Fix
“Contour interval must be greater than 0.” Interval is 0 or blank Enter an interval
“Too many contour levels (…)” Over 5,000 levels in the range Raise the interval or narrow the range
“No contour lines generated.” The range misses the surface Reselect the surface to refill Min and Max
Min and max belong to the last surface The dialog remembers them Choose the surface again to refill them
A Large Surface warning The surface is over the 3D triangle limit Generate anyway, Adjust Settings, or Cancel

Other ways to use it

Method Result
Start From → Custom Contours on your own datum, such as bench RLs
Sub-layer Name A separate folder per run — for example PitShell
Close Polylines Closed rings, ready for clipping or extruding
Vertex Spacing (m) above 0 Lighter lines for export