DXF is an ASCII format used for interchanging AutoCAD drawings between different
software packages. OGR supports reading DXF files generated by all recent
versions of AutoCAD, and writing DXF files that are compatible with AutoCAD
2004 and later.
DXF files are considered to have no georeferencing information through OGR.
By default, the entire contents of the file are represented as a single OGR
layer named "entities". Features will all have the following generic fields:
- Layer: The name of the DXF layer. The default layer is "0".
- SubClasses: Where available, a list of classes to which an entity belongs.
- ExtendedEntity (GDAL <= 2.2.x): The values of extended entity attributes
all appended to form a single text field, where available.
- RawCodeValues (GDAL >= 2.3.0): Only available when the configuration option
DXF_INCLUDE_RAW_CODE_VALUES is set to TRUE. A string list containing all group
codes and values that are not handled by the DXF reader.
- Linetype: Where available, the line type used for this entity.
- EntityHandle: The hexadecimal entity handle. A sort of feature id.
- Text: The text of labels.
The following entity types are supported:
A reasonable attempt is made to preserve color, line width (lineweight), line
type, text size and orientation via OGR feature styling information when
translating entities. Currently no effort is made to preserve complex line types
(those that include text or shapes) or HATCH fill styles.
- POINT: Produces a simple POINT geometry feature.
- MTEXT, TEXT: Produces a POINT feature with LABEL style information. The
style string may include the following parameters: f s t a c w p dx dy bo it.
Text positioning might not precisely match CAD software (especially the vertical
alignment of MTEXT), as calculation of the exact position would require GDAL to
be aware of the font metrics.
By default, character escapes such as %%p are honored where applicable, and
MTEXT control sequences like \Wx.xx; are stripped. To disable this behavior and
retrieve the raw text values, set the configuration option
DXF_TRANSLATE_ESCAPE_SEQUENCES to FALSE.
- LINE, POLYLINE, LWPOLYLINE: Translated as a LINESTRING. Rounded
polylines (those with their vertices' bulge attributes set) will be tessellated.
Single-vertex polylines are translated to POINT. Polyface meshes are translated
as POLYHEDRALSURFACE geometries.
- (GDAL >= 2.3.0) Translated as a MULTILINESTRING. Only the geometry is
reconstructed; styling applied to individual line elements within the MLINE is
ignored. Fill colors and start/end caps are also omitted.
- (GDAL <= 2.2.x) No support.
- CIRCLE, ELLIPSE, ARC, SPLINE, (GDAL >= 2.3.0) HELIX: Translated as a
LINESTRING, tessellating the curve into line segments.
(GDAL >= 2.3.0) CIRCLEs with nonzero "thickness" (cylinders) are
approximated as a POLYHEDRALSURFACE.
- INSERT: By default, the block definition referenced by the INSERT will
be inserted as a compound geometry (for example, a MULTILINESTRING for a block
containing many lines, or a GEOMETRYCOLLECTION for a block that contains points
and lines). If the block contains TEXT or MTEXT entities, they are not merged
into the compound geometry and are instead returned as separate features.
Three configuration options are available to control the behavior of INSERT
- DXF_MERGE_BLOCK_GEOMETRIES: To avoid merging blocks into a compound
geometry the DXF_MERGE_BLOCK_GEOMETRIES config option may be set to FALSE.
Use this option if you need to preserve the styling (such as colors) of
individual linework entities within the block.
- DXF_INLINE_BLOCKS: See below.
- (GDAL >= 2.3.0) DXF_FEATURE_LIMIT_PER_BLOCK: Maximum number of features
inserted from a single block. Set to -1 for no limit. Defaults to 10000.
- ATTDEF, ATTRIB:
- (GDAL >= 2.3.0) Attributes (ATTRIB) are treated as TEXT entities, and
attribute definitions (ATTDEF) inside blocks are ignored. The behavior is
different when DXF_INLINE_BLOCKS is false (see below).
- (GDAL <= 2.2.x) ATTDEF entities are treated as TEXT. ATTRIB entities
are not supported.
- HATCH: Line and arc boundaries are collected as a polygon geometry, but
no effort is currently made to represent the fill style of HATCH entities.
(GDAL >= 2.3.0) The DXF_HATCH_TOLERANCE config option determines the
tolerance used when looking for the next component to add to the hatch boundary.
(GDAL <= 2.2.x) Only line and polyline boundary paths are translated
- 3DFACE, SOLID, (GDAL >= 2.3.0) TRACE: Translated as POLYGON, except for
SOLID and TRACE entities with only one distinct vertex (translated as POINT) or
two distinct vertices (translated as LINESTRING).
- (GDAL >= 2.3.0) The DXF format allows each DIMENSION entity to
reference an "anonymous" block (a block whose name starts with *D) that contains
the geometry of the DIMENSION. If present, this anonymous block will be inlined
at the required position. Otherwise, fallback will occur to a simple DIMENSION
renderer that explodes a linear dimension as a MULTILINESTRING feature.
Arrowheads, if present, are translated as one or more additional features. The
fallback renderer will render nonlinear dimensions as if they were linear.
- (GDAL <= 2.2.x) Dimensions are translated as a MULTILINESTRING and
a POINT for the text.
- LEADER, MULTILEADER:
- (GDAL >= 2.3.0) The leader line is translated as a LINESTRING (LEADER) or
MULTILINESTRING (MULTILEADER). Arrowheads, if present, are translated as one or
more additional features. Text for MULTILEADER entities is translated into a
POINT feature with a label. Block content for MULTILEADERS is treated as for
INSERT. Spline leaders are tessellated into line segments.
- (GDAL <= 2.2.x) No support.
- 3DSOLID, REGION, SURFACE: See below.
The approximation of arcs, ellipses, circles and rounded polylines as
linestrings is done by splitting the arcs into subarcs of no more than a
threshold angle. This angle is the OGR_ARC_STEPSIZE. This defaults to four
degrees, but may be overridden by setting the configuration variable
OGR_ARC_STEPSIZE. For splines, the interpolated polyline contains eight
vertices for each control point.
Object coordinate systems (OCS), also known as "extrusions", are supported for
all entities to which they apply as per the DXF specification, except DIMENSION,
LEADER and MULTILEADER. These three entity types also currently lack support for
elevations; the geometries will always be 2D.
The default behavior is for INSERT entities to be exploded with the
geometry of the BLOCK they reference. However, if the DXF_INLINE_BLOCKS
configuration option is set to the value FALSE, then the behavior is different
as described here.
The intention is that with DXF_INLINE_BLOCKS disabled, the block references
will remain as references and the original block definitions will be
available via the blocks layer. On export this configuration will result in the
creation of similar blocks.
- A new layer will be available called "blocks". It will contain one or
more features for each BLOCK defined in the file. In addition to the usual
fields, they will also have a Block field indicating what block they are part
of. (Note, in GDAL 2.2.x and earlier this field was called BlockName.)
- (GDAL >= 2.3.0) ATTDEF entities in the blocks layer will have an
AttributeTag field, giving the tag of the ATTDEF entity.
- The entities layer will have several new fields:
- BlockName: The name of the referenced block.
- BlockScale: The X, Y, and Z scale factors.
- BlockAngle: The angle of the block in degrees.
- BlockOCSNormal (GDAL >= 2.3.0): The unit normal vector of the object
coordinate system (OCS) of the INSERT entity.
- BlockOCSCoords (GDAL >= 2.3.0): The OCS coordinates of the insertion
- BlockAttributes (GDAL >= 2.3.0): The text content of attributes
associated with this block. Each entry in this string list contains an attribute
tag, followed by a space, followed by the text for that attribute (which may be
- INSERT entities will populate these new fields with the corresponding
information (they are null for all other entities).
- INSERT entities will not have block geometry inlined - instead they will
have a POINT geometry for the insertion point.
DXF files may contain 3DSOLID, REGION and SURFACE entities, which contain 3D
modelling data in the undocumented Autodesk ShapeModeler (ASM) format. GDAL
cannot transform these entities into OGR geometries, so they are skipped by
Starting from GDAL 2.3.0, the DXF_3D_EXTENSIBLE_MODE configuration option may be
set to TRUE to include these entities with the raw ASM data stored in a field.
This option will add two new fields:
This feature only works for DXF files in AutoCAD 2013 (AC1027) format and
- ASMData: A binary field that contains the ASM data.
- ASMTransform: A list of 12 real values indicating the affine transformation
to be applied to the entity.
Normally DXF files are in the ANSI_1252 / Win1252 encoding. GDAL/OGR attempts
to translate this to UTF-8 when reading and back into ANSI_1252 when writing.
DXF files can also have a header field ($DWGCODEPAGE) indicating the
encoding of the file. In GDAL 1.8.x and earlier this was ignored but from
GDAL 1.9.0 and later an attempt is made to use this to recode other
code pages to UTF-8. Whether this works will depend on the code page naming
and whether GDAL/OGR is built against the iconv library for character recoding.
In some cases the $DWGCODEPAGE setting in a DXF file will be wrong, or
unrecognised by OGR. It could be edited manually, or the DXF_ENCODING
configuration variable can be used to override what id will be used by
OGR in transcoding. The value of DXF_ENCODING should be an encoding name
supported by CPLRecode() (i.e. an iconv name), not a DXF $DWGCODEPAGE name.
Using a DXF_ENCODING name of "UTF-8" will avoid any attempt to recode the
text as it is read.
DXF files are written in AutoCAD 2004 format. A standard header (everything
up to the ENTITIES keyword) is written from the $GDAL_DATA/header.dxf file,
and the $GDAL_DATA/trailer.dxf file is added after the entities. Only one
OGR layer can be used to create the output file (but many DXF layers can be
created - see below).
Only the first tool (PEN, BRUSH, etc) in the style string is read. The following
style string parameters are understood:
- Point features with LABEL styling are written as MTEXT entities based
on the styling information.
- Point features without LABEL styling are written as POINT entities.
- LineString and MultiLineString features are written as one or more
LWPOLYLINE entities, closed in the case of polygon rings. If the geometry does
not have a constant elevation, a POLYLINE entity is written. An effort is made
to preserve line width and color.
- Polygon, Triangle and MultiPolygon features are written as HATCH entities by
default. To write these features as LWPOLYLINE/POLYLINE entities instead, set
the configuration option DXF_WRITE_HATCH to FALSE. You may need to do this if
your geometries do not have a constant elevation, as the DXF HATCH entity
cannot represent such geometries.
||Available on geometry types
|PEN||Point, (Multi)LineString||color (c); width (w); dash
|BRUSH||(Multi)Polygon, Triangle||foreground color (fc)|
|LABEL||Point||GDAL >= 2.3.0: text
(t); font name (f); font size (s), treated as cap height; bold (bo); italic
(it); text color (c); x and y offsets (dx, dy); angle (a); anchor point (p);
|GDAL <= 2.2.x: text (t); font size (s), treated as cap height; text
color (c); angle (a); anchor point (p)|
The dataset creation supports the following dataset creation options:
Note that in GDAL 1.8 and later, the header and trailer templates can
be complete DXF files. The driver will scan them and only extract the needed
portions (portion before or after the ENTITIES section).
- HEADER=filename: Override the header file used - in place
of header.dxf located in the GDAL_DATA directory.
- TRAILER=filename: Override the trailer file used - in place
of trailer.dxf located in the GDAL_DATA directory.
It is possible to export a "blocks" layer to DXF in addition to the
"entities" layer in order to produce actual DXF BLOCKs definitions
in the output file. It is also possible to write INSERT entities if
a block name is provided for an entity. To make this work the following
The intention is that a simple translation from DXF to DXF with DXF_INLINE_BLOCKS
set to FALSE will approximately reproduce the original blocks and keep
INSERT entities as INSERT entities rather than exploding them.
- A "blocks" layer may be created, and it must be created before the
- The entities in the blocks layer should have the Block field
populated. (Note, in GDAL 2.2.x and earlier this attribute was called
- Objects to be written as INSERTs in the entities layer should have a
POINT geometry, and the BlockName field set. You may also set BlockAngle,
BlockScale, BlockOCSNormal and BlockOCSCoords (see above under DXF_INLINE_BLOCKS
for details). If BlockOCSCoords is set to a list of 3 real numbers, it is used
as the location of the block; in this situation the position of the POINT
geometry is ignored.
- If a block (name) is already defined in the template header, that will be
used regardless of whether a new definition was provided in the blocks layer.
When writing entities, if populated the Layer field is used to set the
written entities layer. If the layer is not already defined in the template
header then a new layer definition will be introduced, copied from the
definition of the default layer ("0").
When writing linestring geometries, the following rules apply with regard to
linetype (dash pattern) definitions.
The intention is that "dot dash" style patterns will be preserved when written
to DXF and that specific linetypes can be predefined in the header template,
and referenced using the Linetype field if desired.
- If the Linetype field is set on a written feature, and that linetype
is already defined in the template header, then it will be referenced from
the entity. If a style string is present with a "p" pattern proportional to the
linetype defined in the header, a linetype scale value is written.
- If the Linetype field is set, but the linetype is not defined in the
header template, then a definition will be added if the feature has an
OGR style string with a PEN tool and a "p" pattern setting.
- If the feature has no Linetype field set, but it does have an OGR
style string with a PEN tool with a "p" pattern set, then an automatically
named linetype will be created in the output file. Or, if an appropriate
linetype was previously created, that linetype will be referenced, with a
linetype scale if required.
It is assumed that patterns are using "g" (georeferenced) units for
defining the line pattern. If not, the scaling of the DXF patterns is likely
to be wrong - potentially very wrong.
GDAL writes DXF files with measurement units set to "Imperial - Inches". If you
need to change the units, edit the
variables in the header template.
AutoCAD 2014 DXF Reference
DXF header reference