Convert 3D Polyline to 2D: A Simple Guide

Posted by

Converting a 3D polyline to a 2D polyline can be a useful task in many design and drafting applications. By converting the polyline, you can simplify the drawing and make it easier to work with. The process of converting a 3D polyline to a 2D polyline is straightforward and can be done in a few simple steps.

The first step in converting a 3D polyline to a 2D polyline is to select the polyline you want to convert. Once you have selected the polyline, you can use the “FLATTEN” command to convert it to a 2D polyline. This command will project the polyline onto the current UCS plane and create a new 2D polyline that is aligned with the current view.

It’s important to note that when you use the “FLATTEN” command, any elevation data associated with the polyline will be lost. This means that the resulting 2D polyline will only contain X and Y coordinates. However, this can be useful if you want to create a simplified version of your drawing or if you need to export the polyline to a program that only supports 2D geometry.

Understanding 3D Polylines

What is a 3D Polyline?

A 3D polyline is a sequence of connected line segments that have x, y, and z coordinates. In other words, it is a set of lines that are defined in three dimensions. Each line segment has a starting point and an ending point, and these points are defined by their x, y, and z coordinates.

How are 3D Polylines Used?

3D polylines are commonly used in computer-aided design (CAD) software to represent complex shapes and objects in three dimensions. They are also used in geographic information systems (GIS) to represent terrain and other three-dimensional features.

One of the advantages of using 3D polylines is that they can be manipulated in three dimensions, which allows for more accurate modeling of complex shapes and objects. For example, a 3D polyline can be used to represent the path of a curved road, which would be difficult to model using only 2D lines.

Another advantage of using 3D polylines is that they can be used to create cross-sectional views of objects. By slicing a 3D polyline at different points along its length, it is possible to create a series of 2D cross-sectional views that can be used to analyze the object’s shape and structure.

In summary, 3D polylines are an important tool for modeling complex shapes and objects in three dimensions. They are commonly used in CAD and GIS software, and their ability to be manipulated in three dimensions makes them a powerful tool for creating accurate models and analyzing objects.

Converting 3D Polylines to 2D

Why Convert 3D Polylines to 2D?

Converting 3D polylines to 2D can be useful in a variety of situations. For example, if you need to create a 2D drawing of a 3D object, you may want to convert the 3D polylines to 2D. This can also be helpful if you need to calculate the area or perimeter of a 3D object and only need the 2D information.

Methods for Converting 3D Polylines to 2D

There are a few different methods you can use to convert 3D polylines to 2D. Here are a few options:

  • FLATTEN: This AutoCAD command allows you to flatten 3D polylines to 2D. Simply select the 3D polyline you want to flatten and enter the FLATTEN command. You can then choose to flatten the polyline to a specific plane or to a user-defined plane.

  • PEDIT: Another option is to use the PEDIT command to convert 3D polylines to 2D. Select the 3D polyline you want to convert and enter the PEDIT command. Choose the “Convert to 2D Polyline” option and the polyline will be converted to 2D.

  • Explode and Rejoin: You can also explode the 3D polyline and then rejoin it as a 2D polyline. Simply select the 3D polyline and enter the EXPLODE command. Then, select the resulting lines and enter the JOIN command to create a 2D polyline.

No matter which method you choose, it’s important to double-check the resulting 2D polyline to ensure that it accurately represents the original 3D polyline.

Overall, converting 3D polylines to 2D can be a helpful tool in a variety of situations. By using the methods outlined above, you can easily convert your 3D polylines to 2D and use the resulting information as needed.

Using 2D Polylines

What is a 2D Polyline?

A 2D polyline is a type of AutoCAD object that consists of one or more connected line segments. Unlike a 3D polyline, which has a Z coordinate, a 2D polyline only has X and Y coordinates. This makes it useful for representing flat, two-dimensional shapes such as floor plans, maps, and schematics.

How are 2D Polylines Used?

2D polylines are used in a variety of ways in AutoCAD. Here are a few common use cases:

  • Drawing boundaries: 2D polylines are often used to define the boundaries of a property or building. By drawing a closed polyline around the perimeter of a plot of land, for example, you can easily calculate its area.
  • Creating paths: 2D polylines are also useful for creating paths or routes. By drawing a polyline along a road or trail, you can create a path that can be used for navigation or analysis.
  • Representing shapes: 2D polylines can be used to represent a wide range of shapes, from simple rectangles and circles to complex polygons. By connecting multiple line segments together, you can create any shape you need.

In addition to these use cases, 2D polylines can also be used in conjunction with other AutoCAD objects, such as text, dimensions, and hatch patterns, to create detailed and informative drawings.

Overall, 2D polylines are a versatile and essential tool for anyone working with AutoCAD. By mastering the basics of polyline creation and manipulation, you can create accurate and effective drawings that convey your ideas clearly and efficiently.


In conclusion, converting a 3D polyline to a 2D polyline is a useful technique in many fields, including architecture, engineering, and construction. By converting a 3D polyline to 2D, it becomes easier to view and edit the polyline, which can save time and increase efficiency.

In this article, we have discussed several methods for converting a 3D polyline to a 2D polyline using various software programs. These methods include using the FLATSHOT command in AutoCAD, using the EXPORT command in SketchUp, and using the CONVERTPOLY command in BricsCAD.

It is important to note that each software program may have its own specific method for converting 3D polylines to 2D, and it is recommended to consult the software’s documentation or online resources for specific instructions.

Overall, converting a 3D polyline to a 2D polyline can be a simple and effective way to improve workflow and productivity in various industries. By utilizing the methods discussed in this article, users can easily convert 3D polylines to 2D and make the most out of their software tools.