Polyline Edit & Spline Commands
Master AutoCAD polyline editing and spline commands
Essential AutoCAD Commands Covered
Polyline Edit (PEDIT)
Join unconnected line segments into continuous polylines. Access via PE command or Modify panel button.
Spline Tool
Create smooth curved paths with control vertices. Start with SPL command or Draw panel button.
This tutorial uses the Polyline Edit-Ranch.dwg file containing overlapping polygons that will be trimmed and joined into a complete floor plan outline.
Exercise Preview
Exercise Overview
Mastering the Polyline Edit (PEDIT) command is essential for professional AutoCAD workflows. In this comprehensive exercise, you'll discover how to transform disconnected line segments into unified polylines and apply sophisticated curving techniques. The ability to join disparate elements into cohesive objects dramatically streamlines editing and modification processes—a critical skill for efficient drafting. Access Polyline Edit by typing PE Enter or clicking the Polyline Edit button 
in the expanded Modify panel or Modify II toolbar.
Polyline Edit Command Access Methods
Keyboard Shortcut
Type PE and press Enter to start the Polyline Edit command
Modify Panel
Click the Polyline Edit button in the expanded Modify panel
Toolbar Access
Use the Polyline Edit button on the Modify II toolbar
Polyline Edit & Spline
Begin by opening Polyline Edit-Ranch.dwg. This file presents a realistic scenario: an outer perimeter of a residential floor plan constructed using individual Line segments with intentional overlapping polygons. This approach mirrors real-world drafting practices where complex geometries are built incrementally, then refined using Trim and Polyline Edit tools to create clean, unified outlines.
Deploy the Trim tool strategically to eliminate extraneous polygon sections and perimeter segments, leaving only the clean floor plan outline shown below. Professional tip: Leverage the eRase option within the Trim command for immediate cleanup of unwanted segments, or address any remaining elements after completing the primary trim operation. This methodical approach ensures precision—a hallmark of professional drafting standards.
Now for the critical transformation: converting individual line segments into a unified polyline using Polyline Edit. This process is fundamental to professional workflow efficiency, as unified polylines can be offset as single entities—essential for creating wall systems and complex geometries.
Initiate the command by typing PE Enter. Notice that AutoCAD defaults to single-object selection, but the Command line reveals a Multiple option. Press M Enter to unlock multi-selection capability. Select all outline segments and press Enter. When prompted to Convert Lines, Arcs, and Splines to polylines, press Enter to accept the default "Yes"—this conversion is necessary for the joining process.
From the Polyline Edit options menu, select Join via Dynamic Input or press J Enter. The system will prompt for a Fuzz Distance—a tolerance value for bridging small gaps between endpoints. Here's a crucial professional insight: While fuzz distance can mask minor connection errors, precision drafting demands zero tolerance. Gaps typically indicate drafting errors that should be corrected at the source rather than masked. Press Enter to maintain the default Fuzz Distance of Zero.
The segments are now unified, but the command remains active—Polyline Edit offers extensive functionality beyond joining. Press Enter or Esc to complete the operation.
Alternative workflow: If you skip the initial Multiple option, AutoCAD will prompt for segment selection after choosing Join. This method bypasses the Fuzz Distance prompt, offering a streamlined approach for experienced users.
The floor plan perimeter now functions as a single polyline entity, enabling unified offset operations for wall creation—a technique you'll apply in the subsequent exercise.
The Polyline Edit command extends beyond joining—it's also your gateway to sophisticated curve creation and modification. Examine the kidney-shaped pool behind the house, originally drawn with the Polyline tool. Since it's already a polyline, you can access editing functions immediately by double-clicking the object.
Double-click the pool to launch Polyline Edit. Three curve options appear in both the Dynamic Prompt and Command Line: Fit, Spline, and Decurve. Understanding their distinct behaviors is crucial:
- Fit: Creates curves that pass directly through each vertex, maintaining exact point contact
- Spline: Uses vertices as control points, generating smoother, more organic curves that approximate the path
- Decurve: Restores straight segments, allowing iterative design refinement
Experiment with both Fit and Spline options. Exit the command after each selection and click the curve to visualize how each method interprets the vertex relationships. This hands-on comparison builds intuitive understanding of curve behavior. Conclude with Spline selected and exit the command.
For organic shapes requiring maximum flexibility, the dedicated Spline tool offers superior control over curve generation. This tool has become increasingly important in contemporary design workflows, particularly for landscape architecture and modern architectural forms.
Launch the Spline tool by typing SPL Enter or clicking the Spline Button
in the expanded Draw Panel or Toolbar. Create a kidney-shaped hot tub adjacent to the existing pool, following the configuration shown below. Utilize the Close option for the final segment—this ensures smooth endpoint transitions and professional curve quality.After creation, select the spline to reveal a dropdown arrow List icon. Click this icon to access two grip configuration options: Fit and Control Vertices. While neither changes the spline geometry, they fundamentally alter how control grips behave during editing. The Control Vertices option provides grip behavior similar to the Spline option within Polyline Edit, offering nuanced control for precise adjustments.
Experiment with both options and refine the hot tub shape to your preference. Ensure the form intersects both straight pool segments as illustrated—this intersection is essential for the trimming operation that follows.
Complete the pool complex integration using the Trim tool to seamlessly connect the hot tub with the main pool. This operation demonstrates how organic spline curves integrate with existing geometry through precise editing tools.
The workflow you've mastered represents industry-standard practice for architectural floor plan development. Professional drafters routinely construct outer perimeters using whatever drawing tools best suit the geometry, then employ Polyline Edit to create unified polylines suitable for offset operations. This approach offers maximum flexibility during the conceptual phase while ensuring efficiency during detail development.
The strategic decision between drawing directly with the Polyline tool versus converting individual lines depends on project complexity and revision requirements. Complex geometries often benefit from the incremental line-based approach, while simpler forms may warrant direct polyline creation.
In the next exercise, you'll expand this floor plan foundation using Offset, Line, Trim, and Extend commands, building upon the solid polyline framework you've established.
Floor Plan Outline Creation Process
Trim Overlapping Lines
Use the Trim tool to delete polygon sections, leaving only the floor plan outline. Use eRase option for leftover segments.
Start Polyline Edit
Type PE Enter, then press M Enter to enable Multiple selection mode for selecting all outline segments.
Convert and Join
Accept conversion of lines to polylines, select Join option, and set Fuzz Distance to zero for precision.
Always use zero Fuzz Distance to maintain precision in drafting. If gaps exist, correct the underlying mistakes rather than using Fuzz Distance to bridge them.
Polyline Edit Selection Methods
| Feature | Multiple Option | Standard Selection |
|---|---|---|
| Initial Setup | Press M Enter first | Select single object |
| Object Selection | Select all segments upfront | Select after Join option |
| Fuzz Distance | Prompted to enter distance | No fuzz distance prompt |
Polyline Curving Options
Fit Curve
Creates curves that pass through each vertex point, maintaining exact intersection with all control points.
Spline Curve
Uses vertices as guides for smoother curves, creating more natural flowing paths without strict vertex intersection.
Decurve
Removes all curves and returns polyline segments to straight lines, reversing previous curve operations.
Creating Splines with the Spline Tool
Start Spline Command
Type SPL Enter or click Spline button in expanded Draw Panel to begin creating curved paths.
Draw Shape
Click points to define the spline path. Use Close option for the final segment to create smoother endpoints.
Adjust Control Points
Select spline and use dropdown to choose between Fit and Control Vertices grip configurations for editing.
Create floor plan outer perimeters with any necessary drawing tools, then use Polyline Edit to convert to a single polyline for efficient offsetting operations.
Key Takeaways