Drawing and Editing Polylines

Modified on Thu, 16 Oct at 5:07 PM

Drawing and editing polylines

In Pythagoras, you can flexibly draw and edit polylines.
A polyline consists of vertices that connect segments. Each segment can be a line, an arc, or a curve. Polylines also support 3D heights and can be linked to terrain models (DTM) or point clouds.

Draw a polyline

Create polyline

Found in the Create toolbox (icon with multiple segments).

1. Activate the Create polyline tool in the control panel.

2. Click to place the starting point of the polyline.

3. While placing vertices, you can:

Press Spacebar to switch between line, arc, and curve segment.
Press Esc or Del to undo the last segment.
Press Enter to confirm the polyline.

4. Click to place each additional segment.

Press Esc or Delete to remove one or more segments.

4. To finish, press Enter or click the last point again.

If you start by clicking on another polyline, that segment highlights. You can enter a distance for the new vertex relative to the start or endpoint of the existing segment in the Control panel. Use Tab to toggle between options.

Adding height during drawing:

Each vertex takes the height (Z) from the click location.
When Snap Info is active, you can control which object types the cursor snaps to.
Hold P to temporarily snap only to points.
The Z-value appears in real time in the Control panel.
If you place a vertex without snapping, press Enter to manually enter the height.

Result: The polyline is created in 3D when all vertices have heights.

Snap settings (link to article: Object snapping)

Drawing a parallel polyline

Create a parallel copy of an existing polyline at a set distance. Height is preserved.

In the Create toolbar, choose Parallel Object.
Click on the existing polyline to duplicate.
Move the cursor. A preview of a polyline parallel to the reference will be shown.
Click to set the direction of displacement.
Enter the exact distance (Control Panel) and confirm ENTER.

Splitting a polyline

Split into two parts

Split an existing polyline at a chosen segment, creating two separate polylines.

In the Edit toolbar, select Split polyline .
Click the polyline you want to split.
Click an endpoint or midpoint of a segment to split there.
Repeat to make multiple splits.
Press Spacebar to finish.

Explode into individual segments

Convert a polyline into individual objects (points, line segments, or arc segments).

Right-click the polyline and choose Edit > Explode.

Joining or merging polylines

Close gaps using Join polylines

Closes the gap between two non-touching polylines into one continuous polyline by drawing an extra segment.

In the Edit toolbar, choose Join two polylines.
Click an end vertex of the first polyline.
Press Spacebar to switch segment type (line / arc / curve).
Click an end vertex of the second polyline.

Result: Both polylines are joined by a new segment and now form a single polyline.

Merge polylines into one single polyline

You can also merge adjacent, touching polylines via Right-click > Selection > Edit > Merge polylines.

Edit a polyline in detail

Modify vertices within a single polyline.

In the Edit toolbar, choose Edit polyline.

1. Click the polyline to edit.

2. Editing options:

Move vertices in X, Y, or Z (by snapping or manually).
Add new line segments by moving midpoints.
Delete segments by moving one endpoint onto another.
Arc segments:
- Change the radius by moving the arc center point.
- Double-click the end or midpoint to reconnect smoothly.
Change height (Z) or slope: Ctrl + double-click a vertex.

Adjust absolute height of a vertex:
Ctrl + double-click the polyline-vertex with the Selection tool to open the Control panel and enter a Z-value.

Edit a polyline as a whole

Actions that modify the entire polyline:

Right-click the polyline and choose Edit > [option]

Smooth

Converts sharp line transitions into curves, making the shape smoother.
Vertex count remains the same, only segment types change.

Unsmooth

Converts all segments (including arcs or curves) into straight line segments.
Vertices remain, but corners become sharp again.

Linearise

Approximates arcs and curves with short straight line segments to simplify geometry.
Accessible via Right-click > Edit > Simplify Polylines.

Simplify

Reduces the number of vertices by applying a tolerance (maximum deviation).
The overall shape is kept, but with fewer segments.
Use Right-click > Edit > Simplify polylines.

Adjust the height of polyline as a whole (absolute or relative)

Adjust absolute height:
Ctrl + double-click the polyline (not a vertex) with the Selection tool to open the Control panel and enter a Z-value.

Adjust absolute or relative height:

Option 1: Use Right-click > Edit > Change Elevation. absolute or relative

Option 2: Go to Format > Change Elevation.

Applies to all selected vertices and supports both absolute and relative adjustments.

Assign a height gradient

Design polyline elevations...

Applies a slope or height gradient along an existing polyline. Read: -> Design Tools: Polyline/Path Elevations.

Project onto DTM

Right-click the polyline and choose Edit > Project on DTM.
This splits the polyline into segments according to the DTM triangles and assigns each vertex a height from the DTM.

Find with same attributes

Quickly select all polylines that share identical properties within the drawing.

-> Use the Find dialog to locate duplicates and similar data

Annotate polylines

You can add:

Slope annotations to show incline percentages between start and end points.
Length annotations to display total or segment lengths.

Both options are available under annotation settings.