AutoCAD (.dwg/.dxf) and Microstation (.dgn) files are read directly as ArcGIS feature datasets and are valid input to geoprocessing tools, Python scripts, and ModelBuilder iterators as read-only datasets and feature classes without a need to convert the data. The CAD feature dataset is a valid read-only dataset and its feature classes can be used by most geoprocessing tools that support feature layers. Geoprocessing tools such as Copy, Export Features, Merge, Append, and Copy Features can all accomplish the task of permanently converting CAD in-memory feature classes to ArcGIS datasets such as geodatabases or shapefiles. The automation of the analysis and conversion of CAD data can be accomplished using Python and ModelBuilder workflows, or you can use analysis tools directly on CAD feature layers without conversion.
CAD feature classes as map layers
Adding a CAD dataset to a map generates a CAD group layer of feature layers that are organized by their source CAD layers by default. Alternately, CAD feature classes can be defined as ArcGIS Pro feature layers with the Make Layer tool and used in scripts and models in which the required input to a tool is a feature layer rather than a feature class.
CAD feature classes in analysis and GIS data creation
CAD feature layers and feature classes are valid read-only inputs to many analysis and data creation geoprocessing tools. Using tools such as Frequency can help you understand the composition of your CAD drawings and help in reporting such as building bills of materials and quantity takeoffs. You can use geoprocessing tools to further extract useful information from geometry and CAD element parameters as GIS data and create geometries and derived GIS features.
CAD file feature dataset
Geoprocessing tools that accept read-only datasets accept the CAD file feature dataset as valid input. You can, for example, iterate through a folder of CAD drawings using the iterators of ModelBuilder, or treat a CAD file as a file in a Python script. Geoprocessing tools that work with read-only files will also accept the CAD file as input.
Common CAD geoprocessing uses
Data migration is one of the primary uses of geoprocessing on CAD data sources. CAD drawings including AutoCAD Civil 3D and its design content can be a useful source of information to build asset views stored in ArcGIS from the construction and design information found in CAD files.
There are many geoprocessing tools that work with CAD data. Common tools for working with CAD data for the purpose of data interoperability, data migration, and analysis include, but are not limited to, the following:
- Export Features—Converts a feature class or feature layer to a feature class. You can use this tool to convert CAD features to GIS features; this tool differs from the Copy Features tool in that you have more control over how attributes are handled.
- Copy—Makes a copy of the input data. You can use this tool to copy feature classes or the entire CAD file.
- Copy Features—Copies features from the input feature class or layer to a new feature class. Converting CAD data to GIS data is as straightforward as copying it since it is already converted in memory when it is read.
- CAD To Geodatabase—Reads a CAD dataset and creates feature classes of the drawing. The feature classes are written to a geodatabase feature dataset. This tool is like a combination of merge and export features, especially useful in combining the contents of multiple CAD drawings into a geodatabase that you can manipulate further.
- Export to CAD—Exports ArcGIS feature layers to CAD files. Exported AutoCAD files contain ArcGIS feature layers readable by ArcGIS for AutoCAD and ArcGIS Desktop. You can accept the useful defaults of the tool or use the many options to override the defaults with data-driven field values to create complex CAD drawings to exacting CAD standards.
- Merge—Combines multiple input datasets into a single new output dataset. This tool can combine CAD point, line, or polygon feature classes or tables. GIS datasets are often combinations of data from multiple sources including multiple GIS and CAD files.
- Append—Appends multiple input datasets to an existing target dataset. Input datasets can be feature classes, tables, shapefiles, rasters, or annotation or dimensions feature classes. GIS datasets are often combinations of data from multiple sources including multiple GIS and CAD files.
- Feature to Polygon—Creates a feature class containing polygons generated from areas enclosed by input line or polygon features. This tool is useful to build GIS polygons from CAD line work and also to attach attributes from CAD TEXT or other CAD POINT features such as blocks or cells with those attributes—for example, building a GIS polygon dataset of lots from CAD lot lines, and blocks with attributes that are located within those CAD boundary lot lines.
- Spatial Join—Joins attributes from one feature to another based on the spatial relationship. The target features and the joined attributes from the join features are written to the output feature class. Useful for building relationships such as CAD TEXT or CAD block INSERT entities near lines or points to assign their annotation to the features they are near.
- Add Field—Adds a new field to a table or the table of a feature class or feature layer, as well as to rasters with attribute tables. To take advantage of the Export to CAD tool to use data-driven overrides to control the construction of output CAD files according to specific CAD standards, you can add key named fields to the input GIS data that is recognized by that tool. Alternatively, you can create alias names for existing fields containing valid values to drive CAD symbology or linked tables with valid values in key named fields.
- Add CAD Fields—Adds several reserved CAD fields in one step. Fields created by this tool are used by the Export to CAD tool to generate CAD entities with specific properties. After running this tool, you must calculate or type the appropriate field values. You should also delete fields you are not using to avoid modifying CAD properties to null or zero values unintentionally before using the Export to CAD tool.
- Delete Field—Deletes one or more fields from a table, feature class, feature layer, or raster dataset. You should delete fields after using the Add CAD Fields tool if you are not populating those fields with valid values to avoid modifying CAD properties to null or zero values unintentionally before using the Export to CAD tool.
- Calculate Field—Calculates the values of a field for a feature class, feature layer, or raster. This tool is useful to populate key named fields in GIS feature layers before the use of the Export to CAD tool to control the properties of an output CAD drawing.