What is CAD data?

Computer-aided design (CAD) is a system of hardware and software used by design professionals to design and document real-world objects. Currently, AutoCAD and MicroStation are the two most widely used general-purpose CAD platforms. These systems are designed to accommodate a wide range of applications. Organizations involved in the engineering, architecture, surveying, and construction industries use them to provide a variety of services.

ArcGIS for Desktop accepts data generated by AutoCAD- and Microstation-based applications. This topic describes in general terms the types of data generated by both systems.

CAD data

CAD systems generate digital data. CAD data can serve a range of purposes—from a design plan that is printed as a drawing or submitted as a legal document, to a repository for ongoing as-built information. The datasets can vary in size, scale, and level of detail; they can represent information about the inside of a building at a project scale or a survey plat at a regional scale in a projected grid zone.

Formats

AutoCAD and MicroStation each use a proprietary file-based vector format. Both formats are capable of supporting 2D and 3D information.

Autodesk AutoCAD DWG/DXF

The DWG format is the most widespread format used to create and share CAD data. In addition to Autodesk's proprietary versions, several third-party variants are also common.

The DXF format is an interchange format originally developed in 1982 by Autodesk for enabling interoperability with other software applications. Its usefulness is declining as software applications increasingly support the DWG format directly with licensed read/write technology from Autodesk or from third-party providers such as the Open Design Alliance.

Bentley MicroStation DGN

The DGN format is not as prevalent as the AutoCAD formats but remains a critical format for large engineering projects that use CAD data. A unique feature of the DGN format is you can save it with nonstandard file extensions. This can be utilized to denote content; for example, you can save a DGN file with a .par extension to identify drawings containing parcel information.

Learn more about CAD data

To learn more about source CAD data, you can reference the following topics:

Topic	Description
About CAD coordinate systems	The issue of scale defines a fundamental difference between how GIS and CAD systems utilize coordinate systems. This topic explains CAD coordinate systems and why integrating CAD data with maps can sometimes be problematic.
How CAD data is organized	Unlike a GIS, all data represented by a CAD dataset is normally contained in a single source file. This topic explains what comprises a CAD file and how DWG/DXF and DGN formats organize data.
Types of user-created attributes in CAD drawings	DWG/DXF and DGN formats each use different methods for storing user-created attributes. This topic describes the types of attributes you can encounter when working with CAD datasets.