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Drawing a section

Preparing the drawing

The program works on the model space and only considers entities that carry an elevation:

Entity Elevation used
Polyline (LWPOLYLINE) the polyline Elevation property (the whole curve at the same height, like a contour line)
2D polyline the Elevation property
3D polyline the Z of each vertex, interpolated along the intersected segment
  • Entities on layers that are off are ignored: switch off the layers of roads, buildings, labels, grids, etc. so they do not add points to the profile.
  • Lines, arcs, splines, 3D faces and meshes are not considered: convert them to polylines (for example with PEDIT › Join or CONVTOPOLYLINE) and assign the elevation.
  • The sample drawing Carta Tecnica 2000.dwg in the package is ready to try.

Cross Section command

  1. Menu Geostru › DrawSection › Cross Section (same as the -VBARUN command with macro DrawSection.sezione).
  2. At the Inizio Sezione prompt (section start) click the first point of the section line on the plan.
  3. At the Fine sezione prompt (section end) click the second point. The section line is drawn as a line in the drawing; it may start and end at any distance from the contours.
  4. The program computes the intersections and asks Where drawing?: click the point where you want the section drawn. That point is the bottom-left corner of the section frame. Pick a free area of the drawing (usually beside the plan).

No intersections

If the section line does not cross any entity with elevation on the layers that are on, build 2026.1 shows a message; older releases draw nothing. Check that the contour lines are polylines with an elevation and that their layers are on.

What is drawn

  • The terrain profile (blue polyline) at the vertical scale you set, with a vertical line at every intersection point.
  • The datum elevation of the comparison plane, equal to the minimum elevation of the section minus 5 m, written on the left.
  • The title block below the profile, with one row for:
    • CODICE — sequential number of the point;
    • PROGRESSIVA — chainage, i.e. distance from the first point of the section;
    • PARZIALE — partial distance from the previous point;
    • QUOTA — ground elevation.
  • The scales SCALA H 1/… (horizontal) and SCALA V 1/… (vertical) at the top left.
  • A bounding rectangle around everything.

Distances are horizontal distances along the section line; the first intersection is chainage 0.

Scales, text height and the height of the title-block rows are set in Settings before drawing the section. The result is made of ordinary AutoCAD entities (lines, a polyline, text): you can edit, move or delete it like any other object.

Further sections

Repeat the command for each section. The last section drawn stays in memory until AutoCAD closes and is the one written by Export: export right after drawing, before tracing another one.