DXF Format

The DXF (Drawing Interchange File) format was developed to help the communication between the AUTOCAD and other programs. These files can be transformed to other CAD systems or other programs.

The DXF files are text files in the ASCII format.

The organization of a DXF file has the following format:

  1. "Header" - general information about the file;
  2. tables section - presents information in tables format of the lines type, text, coordinates, information layer, that is, visualization types;
  3. blocks section - presents an entities groups definition;
  4. entities section: this section presents the data, by using points, lines, circles, arcs, etc;
  5. end of file section: presents only the information about entities section and end of file. The entities section only presents reference for the selected output objects.

The SPRING uses the entities section and tables at the importing moment of the DXF format for the SPRING.

The SPRING imports DXF data in the thematic and numeric models and for that, it is required that the data has been digitized following some criteria. For thematic data the SPRING imports only lines and points. The lines have to be digitized in the AUTOCAD in the "line" format, or "polyline" format, the user should be careful when correcting lines.

The identifier representing the line color characteristics, must be of the "Point" type with an associated color and has to be placed at any point inside the polygon. At the digitalization moment the user has to have a color associated to the digitalized object or to the whole information layer. As an importing product one has to have, closed polygons with specific color by the identifier, and polygonal lines with the line color or plane (In this SPRING version identifiers are not imported).

At the lines importing moment the SPRING automatically makes an error adjust with a value smaller than 0.5mm (Adjusted Lines option). Polygons with an error greater than 0.5 mm are imported as polygonal lines. After importing Lines and Identifiers the system executes the polygonalization. Lines that were not adjusted or that do not make polygons are transformed in polygonal lines, and can be properly corrected and identified inside the SPRING environment.

For numerical data in the DXF format, the SPRING imports spot heights, that is, data in the (X, Y, Z) format, where X and Y are the planar coordinates and Z the height value. The spot heights have to be digitized in the AUTOCAD as "line" or "Polyline", and the spot heights as "Point".

NOTE: A DXF file can be imported in planar coordinates (meters, kilometers, millimeters, feet or inches), or geographical coordinates (decimal degree or decimal second), but only exported in planar coordinates (meters).

To import or export DXF data!



The following example shows a DXF file with part of a three points line. Notice the file sections.


0
SECTION
  2
HEADER
  9
$EXTMIN
 10
653162.812500
 20
7400148.000000
 30
0.0
  9
$EXTMAX
 10
661762.812500
 20
7409548.000000
 30
0.0
  0
ENDSEC
  0
SECTION
  2
TABLES
  0
TABLE
  2
LAYER
 70
     1
  0
LAYER
  2
Rural_map
 70
     0
 62
     7
  6
CONTINUOUS
  0
ENDTAB
  0
ENDSEC
  0
SECTION
  2
ENTITIES
  0
POLYLINE
  8
Rural_map
 66
     1
 10
0.0
 20
0.0
 30
0.0
 70
     8
  0
VERTEX
  8
Rural_map
 10
653998.696754
 20
7408566.580065
 30
300.000000
 70
    32
  0
VERTEX
  8
Rural_map
 10
654317.529622
 20
7408540.712912
 30
300.000000
 70
    32
  0
VERTEX
8
Rural_map
 10
656523.508381
 20
7404108.807535
 30
300.000000
 70
    32
  0
SEQEND
  8
Rural_map
  0
ENDSEC
  0
EOF


Data Import and Export


See also:
How to IMPORT data?
How to IMPORT SGI data?
How to IMPORT GRIB images?
How to EXPORT data?