• Table of Contents
Femtet Help/Manual
 

Home / Technical Notes / Modeler / DXF File Import/Export Specifications

DXF File Import/Export Specifications

Entities in DXF file

DXF file import

DXF file export

Import Setup "Round off to [x] decimal digits"

Import Setup "Polygonal approximation of circle/arc "

Import Setup "Remove edges shorter than [x]"

Import Setup "Linear interpolation"

1. Entities in DXF file

Graphical objects are defined by ENTITIES in DXF file.

Femtet supports the entities listed below.

Other entities not listed here, such as TEXT, 3DSOLID, BODY etc, are not supported.

 

  • Before importing or exporting, please check which entities are used in your CAD system.

Entities

 Graphical Objects Notes

POINT

 Defines a point.

LINE

Defines a line.

ARC

 Defines an arc.
CIRCLE Defines a circle.
ELLIPSE Defines an ellipse or an elliptical arc.
POLYLINE Defines an aggregation of line/arc segments.
SPLINE Defines a spline.
SOLID Defines a face formed by lines.
HATCH Defines a face formed by LINE/ARC/ELLIPSE/POLYLINE/SPLINE border.
BLOCK Defines a object formed by multiple entities.

 

2. DXF file import

DXF entities are imported to Femtet as described below..

 

Femtet tries to import the objects as sheet body if it can.

If not possible, they will be imported as wire body.

The failure to convert to sheet body is usually caused by minute wire bodies occasionally included in the imported CAD data.

This problem might be solved by identifying and removing such bodies.

See [Conversion Failure from Wire Bodies to a Sheet Body] regarding the recovery method.

If you cannot correct the problem in Femtet, you need to solve it in the original CAD system.


Entity

Geometry in Femtet

 Notes

POINT

Imported as vertex body.

LINE

Imported as line wire body.

ARC

Imported as arc wire body.

  • The normal-direction information for ARC is ignored.
    Arcs drawn on non-XY plane are forcibly projected on XY plane.
    That might result in unexpected shapes.
CIRCLE Imported as circular sheet body.

  • The normal-direction information for CIRCLE is ignored.
    Circles drawn on non-XY plane are forcibly projected on XY plane.
    That might result in unexpected shapes.
ELLIPSE Imported as elliptical sheet body.

  • Elliptical arc is also imported as elliptical sheet body.
POLYLINE Imported as wire body consisting of line/arc edge topologies.
Belt-shaped
POLYLINE		 Imported as sheet body having the specified width..

  • The width must be constant for the whole length.

 
Closed
POLYLINE		 Imported as sheet body consisting of line/arc edge topologies.
SPLINE Imported as spline wire body.

  • Femtet cannot import crossed splines.
Closed
SPLINE		 Imported as sheet body consisting of spline edge topologies.

  • Femtet cannot import crossed splines.
SOLID Imported as sheet body consisting of line edge topologies.
HATCH Imported as sheet body consisting of line/arc/spline edge topologies.

  • Femtet cannot import HATCH including ELLIPSE boundary.
BLOCK Each entity group in the block is imported individually.

 

3. DXF file export

Bodies in Femtet are exported to DXF as described below.
Femtet cannot export solid bodies.

 

 

Bodies in Femtet

Graphical Objects

 Notes

Vertex body

Exported as POINT.

Wire body consisting of a line edge topology

Exported as LINE.

Wire body consisting of an arc edge topology

Exported as ARC.
Wire body consisting of a circular edge topology Exported as CIRCLE.
Wire body consisting of an elliptical edge topology Exported as EPPLIPSE.
Wire body consisting of an elliptical arc edge topology Exported as EPPLIPSE.
Wire body consisting of a spline edge topology

Exported as SPLINE.

 
Wire body consisting of multiple line/arc edge topologies Exported as LWPOLYLINE.
Wire body consisting of elliptical arc/spline edge topologies Each topology is individually exported as LINE, ARC, ELLIPSE, or SPINE .
Sheet body consisting of a circular edge topology Exported as HATCH.
Sheet body consisting of an elliptical edge topology Exported as HATCH.
Sheet body consisting of multiple line/arc edge topologies

Exported as HATCH.
Sheet body consisting of elliptical arc/spline edge topologies Each topology is individually exported as LINE, ARC, ELLIPSE, or SPINE .

 

 

4. Import Setup "Round off to [x] decimal digits"

The coordinates are rounded off to the specified decimal digits.

With this function, the vertices in a close proximity can be collected to one.

You might find some vertices highlighted when [Check Bodies] is performed on objects imported from DXF. Such a problem might be solved by adjusting the decimal digits.

 

If 16 is specified, the coordinates are not rounded off. If 5 is specified, the coordinates are rounded off.

 

5. Import Setup "Polygonal approximation of circle/arc "

The drawing speed will accelerate if the polygonal approximation is applied on circles or arcs..

Please note that it might result in errors during meshing in some cases.

 

  • Do not use [Circle/arc fitting correction].

[Circle/arc fitting correction] is a function to align vertex coordinates with arc in DXF file data. The coordinates will not be corrected on the edge of the converted polygon.

 

Left Fig: No approximation Right Fig: Approximation (Octagon)

 

6. Import Setup "Remove edges shorter than [x]"

Edges shorter than the specified length are removed.

The minute edges and unneeded vertices that can cause an error in meshing are removed effectively.

You might find some vertices highlighted when [Check Bodies] is performed on objects imported from DXF. Such problems might be solved by adjusting the decimal digits.

There might be a case, however, where the edges shorter than the specified length are not removed depending on the model.

 

Left Fig: No removal (The length is set to nil) Right Fig: Removal (The length is set to a certain value)

 

7. Import Setup "Linear interpolation"


Multiple edge topologies composed of continuous lines/curves are converted to a single-line edge topology. It is useful to remove unneeded vertices and edges.


Left Fig: Without linear interpolation Right Fig: With linear interpolation

Note that it might misinterpret the shapes having a high aspect ratio.

See an example below.

Disable it in such a case.

 

Without linear interpolation

 

With linear interpolation