is a native Autodesk file-based geospatial format that is optimized
for storing large, classified data sets.
SDF is like SHP format
in that it contains both spatial data and attribute data. However,
unlike SHP, it stores both types of data in a single file rather
than a set of files.
When drawing data is
stored as SDF, you can use Autodesk MapGuide Enterprise 2010 to
style and publish the data to the Internet. You can also publish
map data directly to MapGuide, without
exporting to SDF.
The current version,
which works with AutoCAD Map 3D and Autodesk MapGuide Enterprise, is
SDF version 3. AutoCAD Map 3D refers to this version as “SDF.”
SDF version 2 is still
supported by MapGuide 6.5 (and earlier releases), and AutoCAD Map 3D can
import and export SDF 2 using a separate import/export interface.
SDF has the following
advantages over DWG:
- It stores and manages an order of magnitude
more data than DWG
- It is very fast, allowing Autodesk applications,
such as AutoCAD Map 3D and MapGuide, to read and display tens of thousands
of features per second.
- It provides the power of a database without
the overhead and cost of a full relational database management system
(RDBMS) such as SQL Server or Oracle.
- An SDF file can store a single feature
class, or it can store multiple feature classes.
- It is easy to manage, providing access
to the database schema.
If you export to an existing
file, you can choose to overwrite that file or append the new data
to it. Overwriting destroys the existing file and creates a new
one. Appending adds the data in the current export operation to
the existing data without deleting any existing data.
When you append, any
existing classes in the target file remain unchanged. New feature
classes and new properties for existing feature classes will be added.
If the target file contains
properties for which the source file has no values, the resulting
file may show those properties as being null or as having default values,
depending on what was specified in the schema.
If the source data contains
classes that are not in the target file, those classes will be created
and will have the properties of the source data.
index property is added to each feature class when you export. You can
specify the name for this property in the MapExport.ini
A message reports on
the export results. Because some entities belong to multiple feature
classes, the number of entities exported may not match the number
of SDF entities created. The message tells you how many DWG entities
were exported more than once. If you base the exported feature classes on
object data or link templates, an entity may be exported more than
once if more than one data table is attached or linked to it.
SDF has no export driver