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Integrating CAD Data with ArcGIS

Agenda

• An Overview of CAD Drawings• CAD Data Structure in ArcGIS• Visualization• Georeferencing• Data Conversion• ArcGIS for AutoCAD• Q & A

CAD Drawings - Overview

• Widely used vector based spatial data format• Standard format for many organizations• Extensive 2D and 3D geometry support• Entity attribution capabilities• Multi-disciplinary usage

–Engineering, Surveying, Architecture

CAD Integration Scenarios

• Cartography– CAD layers serve as map elements (focus or background)

• Database Integration– CAD feature attributes link with other databases

• Spatial Analysis– CAD feature classes interact with other GIS layers

• Editing– CAD features serve as reference for new features, snapping

• Conversion– CAD feature classes exported into GIS formats (and vice versa)

CAD Drawing Formats and Versions

• ArcGIS supports the two most common CAD file formats– AutoCAD DWG/DXF– MicroStation DGN

• Supported file versions:– DWG/DXF – AutoCAD Release 12 through AutoCAD 2009– DGN – MicroStation 5.x through MicroStation V8

ArcGIS Direct Read Capabilities

• CAD Direct Read – Built In– ArcCatalog– ArcMap– ArcScene and ArcGlobe(to see 3D view of CAD data)

• Core technology• Available at all ArcGIS license levels• No conversion required• No extensions required

– Data Interoperability

CAD Data Model in ArcGIS

CAD data is comprised of:

Geometry Attributes

Coordinate System/Projection World File

CAD entity geometry is represented as GIS feature geometry

CAD data can be projected to overlay with other GIS layers

CAD drawings can be transformed from local coordinates to real-world location

CAD properties and database links are transferred to attribute tables

ABC

CAD Data Structure in ArcGIS

• Viewable as separate feature classes and as a drawing dataset

• CAD feature classes vs. CAD drawing datasets

Parcels.dgn

Annotation

Multipatch

Parcels.dgn

Point

Polygon

Polyline

Parcels.prj

Text, tags and attribute definitions

Polygons and surfaces used for 3D representation

Drawing dataset represents the entire CAD file as a single layer

Points, blocks and cells

Lines, polylines, curves and arcs

Closed areas such as polygons, ellipses and circles

Projection files define a coordinate system for a CAD dataset. They are recommended but not required.

CAD Data Visualization

• Feature and annotation rendering• Directly reads CAD defined properties

CAD Feature Rendering

• Previous design – ArcGIS 9.1 and earlier

– Only continuous lines in a single color– Default font is Arial

• New design – ArcGIS 9.2 and 9.3– Linetypes preserved– Color definitions assigned by RGB

values– Lineweights and linetypes rendered automatically

– Text properties such as bold, italicized and orientation maintained

– True type fonts transfer seamlessly

ESRI-CAD Style

• DGN and DWG categories• Additional symbols can be added• More symbols to come in future releases

Georeferencing – Defining Spatial Reference

• Coordinate systems and projection files• Transformations and world files

Assigning Spatial Reference to CAD Data

• Coordinate Systems– Initial use of CAD drawings in ArcGIS will not have coordinate

system defined– Can select, create or import from another

dataset– Not required, but recommended

• Projection Files– Assigns coordinate system to CAD files– Created in ArcCatalog

• CAD Feature Dataset Properties dialog• Save as .prj file with same name and in

same folder location as CAD file– Can be copied and reused for other CAD

drawings

CAD Transformations

• Two-point similarity transformation method– Scale, Rotate, and Translate– Aspect ratio always maintained– Cannot skew or ‘rubber sheet’ CAD drawing

• Transformation managed by .wld files– World file must use CAD file name– Must also reside in same folder

• Usage– CAD drawings that are created in “paper space” – CAD drawings that do not have a known coordinate system

Transformation Tools

• Transformations tab– Located in the CAD feature Layer Properties dialog– Type in coordinates to define transformation– Apply scale factor and rotation angle by value

Transformation Tools Continued

• Georeferencing Toolbar– Interactively move CAD layer and create control points in ArcMap

Universal Projection and World Files

• Universal Projection File– ESRI_CAD.PRJ– Applies same coordinate system to all CAD files in a workspace

• Universal World File– ESRI_CAD.WLD– Applies identical transformation to all CAD files in a workspace– Useful for set of tiled CAD drawings

Data Conversion: CAD to GIS

• Converting CAD drawings to Geodatabase feature classes

CAD ArcGIS

• Update existing Geodatabases– New as-built information– Geometry (linework) from recent survey

• New Geodatabase based on CAD data sources– Tiled CAD drawings combined to create a seamless dataset– Supporting database

• Editing– Topology– Edge matching; Rubber sheeting

• Advanced cartographic symbolization– Representations; Maplex

Why Convert CAD Data?

Common Geoprocessing Tools for Import

Reformats the CAD data into predefined highly normalized tables and feature classesImport from CAD

Turns tiled CAD files into a single feature classMerge

Used in Model Builder only to select child data elements Select Data

Similar to Make Feature Layer but creates output on diskSelect

Temporary files with field control (Selections)Make Feature Layer

CAD text to GIS annotation feature classesImport CAD Annotation

Similar to Copy Features except includes a query builderFeature Class to Feature Class

Simple way to convert CAD feature classCopy Features

Conversion Methods

• Export Data– Quick way to convert CAD data– Output data container not required

• Copy and Paste in Edit Session– Copy features from CAD feature class– Paste features into existing GDB feature class or shapefile

• Feature Class to Feature Class– Wizard-driven tool– Ability to query/select features for conversion

• Import from CAD and Import CAD Annotation– Support advanced translation workflows

Preparing CAD Data for ArcGIS

• Organize and name layers/levels

• Create data with real-world coordinates

• Use blocks/cells for attributing objects– i.e., points inside polygons or closed polyline areas

• Separate cartographic objects– i.e., title, blocks, legends from geometry

• Use group cells or blocks selectively – Consider exploding process and cell/block origin

• Use entities/elements currently supported by ArcGIS– List of supported CAD entities available in ArcGIS Desktop Help– Avoid use of splines when digitizing in CAD

Converting CAD Point Data to ArcGIS

• Point definition in CAD vs. GIS– Line with zero length– Block/Cell– Marker symbol

• Grabbing point data from blocks/cells – Where is the cell origin?– Where is the block insertion point?– Where will the marker symbol appear, i.e. data

shift?

• Extraneous point data– Insertion points for group blocks/cells– Duplicate information– Assign attributes

• Points inside polygons or closed polyline areas

Converting CAD Line Data to ArcGIS

• Polyline definition in CAD vs. GIS– CAD:

• Line has two vertices• Polyline has three or more vertices

– GIS:• Polyline includes all line-types

• Closed polylines– Duplicates polygon feature class

• Splines and B-Splines

Converting CAD Polygon Data to ArcGIS

• Polygon definition in CAD vs. GIS– CAD:

• Polygon has minimum of four vertices• Last vertex must be in same location as first

vertex, i.e. manually closed– GIS:

• Polygon has a minimum of three vertices• Automatically closed

• Examples of Polygon Data– Closed polylines

• Duplicates polyline feature class– Hatch/Fill– 2D and 3D objects

• Faces• Shapes

– Solids– Surfaces

Considerations for 3D CAD Data

• PolylineZ– Consistent z-values– Spikes

• PolygonZ– Closed polyline with z-value– Shape– Solid– Extrusion necessary?

• Multipatch– Solid – Textured surface– Feature outline

Data Conversion: GIS to CAD

• Converting Geodatabase feature classes to CAD data

ArcGIS CAD

Exporting GIS to CAD Formats

• Provides interoperability between GIS and CAD software– ‘Roundtrip’ workflow

• Enables GIS users to create CAD drawings without having CAD software

• Allows GIS users to generate data in standard CAD formats– AutoCAD DWG/DXF– MicroStation DGN

• User defined attribution and symbology– Seed files

Seed Files for CAD Conversion

• Blank template used to define a new file

• Provides additional control for CAD drawing creation– Symbology; Geometry; Layer/level structure

• CAD standards

• Used to control Blocks or Cell definitions in Export to CAD

• MicroStation requires seed file for design file creation– Design plane, appropriate dimensions, units and origin, 2D or 3D

Mapping Specification for DWG (MSD)

• Open source framework • Developed by ESRI• Codes information in DWGs

– GIS feature classes + attributes– Coordinate systems

• Utilizes CAD standards to define schema and store data

• Leveraged by ArcGIS CAD tools at 9.3– CAD direct read/import tools– Export to CAD

• Provides improved interoperability between CAD and GIS

• Available in the ArcGIS Online Help system:– http://webhelp.esri.com/arcgisdesktop/9.3/index

cfm?TopicName=CAD_data_organization

Mapping Specification for DWG: Export to CAD

Source Geodatabase

Export

Output DWG pre-9.3

Output DWG at 9.3

MSD Feature Class Tools

New feature class name and type

Specify CAD properties

Use property selectors

Define schema and default values

ArcGIS for AutoCAD

• Free ArcGIS Server based product• Runs on AutoCAD 2007 and 2008 based products including

Autodesk Map 3D, Civil, Land Desktop– AutoCAD LT not supported

• Direct access to GIS data within AutoCAD

ArcGIS for AutoCAD Product Overview

• Free – download available (http://www.esri.com/software/arcgis/arcgis-for-autocad/index.html)

• Simple plug-in to AutoCAD

• Allows ArcGIS Server map services to be accessed and displayed inside AutoCAD

• Key Features– Map service display management– Identify, copy and paste attributes to clipboard– Assign, clear or export coordinate system definition of the CAD

drawing

• Lays the groundwork for additional functionality

ArcGIS for AutoCAD Process

Map services directly accessible within

AutoCAD

GIS Server

Map Services

Internet

ArcGIS for AutoCAD

Resources and Training

• ArcGIS Desktop Help (Check Online for Updates!)

• New Instructor-Led Training !• Working with CAD Data in ArcGIS Desktop

• Live Training Seminars• Working with CAD Data in ArcGIS 9.2• Geoprocessing CAD Data with ArcGIS• Authoring and Publishing Optimized Map Services

• Sample Drafting Toolbar (BETA)• Check it out and give us feedback!

Resources and Training