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[Auto]CAD Basics: Foundations and 2D drawings. 7E300 International CA(A)D-course www.ds.arch.tue.nl/education/courses/CAD_International/. Overview. Introduction to CA(A)D-Packages: The promise The real world CA(A)D by Example: AutoCAD & ADT History System architecture Basic Geometry

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Auto cad basics foundations and 2d drawings

[Auto]CAD Basics:

Foundations and

2D drawings

7E300 International CA(A)D-course www.ds.arch.tue.nl/education/courses/CAD_International/


  • Introduction to CA(A)D-Packages:

    • The promise

    • The real world

  • CA(A)D by Example: AutoCAD & ADT

    • History

    • System architecture

  • Basic Geometry

    • Coordinate systems

    • Basic transformations

    • Geometric primitives

  • Construction aids

    • Manual entry

    • Snaps

    • Alignments

Overview continued
Overview continued

  • Construction methods

  • Manipulation methods

  • Printing

  • Getting help

Overview continued1
Overview continued

2nd lecture (Friday):

  • 3D geometry types

  • ‘Intelligent’ composite Objects

  • Architectural objects and helpers

  • Dimensioning

  • Printing

  • Rendering

  • Export


  • Give an overview of the topics involved

  • Give introduction to most basic modeling/drawing techniques

  • Give advise for self-study

  • Give introduction to AutoCAD/ADT

Building model paradigm
Building model paradigm

  • Building is designed assembling different objects

  • Every object of the building has a set of properties that can be interpreted in different contexts

  • Geometrical representations (i.e. drawings) are only one of many aspects. Drawings can be generated dynamically from existing data

  • Different domains (structural engineering, building physics etc.) have different views on building model

Building model paradigm1
Building model paradigm

  • Advantages

    • ‘intelligent’ applications can gather all sorts of data (room sizes, material lists etc.) from a well defined model

    • Dependent drawings such as sections do not have to be redrawn on changes but automatically adapt

Building model paradigm2
Building model paradigm

  • Problems

    • Additional (non-graphical) information has to be provided by architect

    • Coherency when changing objects

    • Object relations have to be designed

    • Complexity with all data required often cannot not be generated at design time

Future developments
Future developments

  • Architect as ‘building programmer’?

  • Advanced input techniques

    • Virtual/Augmented reality

    • ‘Intelligent’ recognition handmade drawings

    • Voice recognition

    • Reuse of design strategies

  • Better compatibility through open standards (IFC etc.)

  • Finally: Paperless office at last?

Introduction to ca a d packages
Introduction to CA(A)D packages

  • The promises:

    • Let repetitive work be done by the machine

    • Draw more exactly

    • Draw quicker

    • Concentrate on the building instead of the drawing

    • Let drawings be generated from a n-dimensional building model

    • Get rid of paper by electronic documents

    • Accelerate cooperative work in the whole building cycle by reusing documents under domain-specific aspects

    • Let ‘intelligent’ functionality take care of easy tasks

Introduction to ca a d packages1
Introduction to CA(A)D packages

  • The real world:

    • CA(A)D in most cases used as 2D pen and paper

    • Additional information required for building model seldom provided by architect

    • Document exchange critical due to lack of standards

    • Applications not error-prone

    • Functionality for architecture domain limited

Caad applications in the architectural domain
CAAD applications in the architectural domain

Marketshare CAAD-packages (Germany 2003) according to online survey on www.aecweb.de

Ca a d by example autocad adt
CA(A)D by example: AutoCAD & ADT

  • History:

    • 1960 Ivan Sutherland SKETCHPAD

    • 1982 AutoCAD 1.0 introduced on COMDEX

    • 1985 AutoCAD 2.1 (R 6) goes 3D

    • 1986 AutoLISP

    • 1992 R 12 with new Solid kernel & rendering

    • 1993 R 12 goes Windows

    • 1997 R 14 most important version ever

    • 1998 ADT on R 14

    • 2000 AutoCAD 2000

Ca a d by example autocad adt1
CA(A)D by example: AutoCAD & ADT

  • System Architecture (very simplified)

End User


VisualizationOpenGL / D3D

Standard AutoCAD UI

API (C/C++, LISP, VB etc.)

Geometry Kernel

Operating System

Elemental computer graphics
Elemental Computer Graphics

  • Coordinate Systems

    • Almost all CAD-applications based on three-dimensional Cartesian system with right-hand orientation

Image source: http://www.vard.org/mono/gait/soutas.htm

Image source: http://en.wikipedia.org/wiki/Cartesian_coordinate_system

Elemental computer graphics1
Elemental Computer Graphics

  • Coordinate Systems can be modified

    • Global: for the entire scene/’world’ (WCS in ACAD)

    • Local to an object / arbitrarily chosen by user (UCS in ACAD)

Global (WCS)

Local (UCS)

Elemental computer graphics2
Elemental Computer Graphics

  • Units

    • Internal units and precision fixed and limited by machine and application

    • Real-world units (m, mm, ft, inches) can be applied arbitrarily suiting own needs

    • Be careful when exchanging data!

    • Choice of units affects dimensioning, text, hatches and line weights in ACAD!

    • Although units can be changed later, conversion problems esp. apply to switch between metric/imperial

Elemental computer graphics3
Elemental Computer Graphics

  • Basic transformations

    • Translate (move)

    • Rotate

    • Scale

Basic geometry
Basic geometry

  • Translation

    • Absolute: Set coordinates directly in current coordinate systemExample:Move absolute 5,1(ACAD: move:5,1)

Basic geometry1
Basic geometry

  • Translation

    • Relative: Set coordinates relative to current location in current coordinate systemExample: Translate relative5,1(ACAD move:@5,1)

Basic geometry2
Basic geometry

  • Rotation

    • Centered to object

Basic geometry3
Basic geometry

  • Rotation

    • Off-center rotation

Basic geometry4
Basic geometry

  • Scale

    • Uniform scaleExample: Factor 0.5 and 2

Basic geometry5
Basic geometry

  • Scale

    • Non-Uniform scale(Achieved by ‘Stretch’ command in ACAD or by scaling blocks)

Geometric primitives
Geometric primitives

  • Geometric primitives 2D

    • Point (Vertex)

    • Elemental type for all other geometry

    • Often used as construction aid

Geometric primitives1
Geometric primitives

  • Line

    • Elemental type used to assemble other geometry types

    • Composed geometry (rectangle etc.) can be broken down to lines

Geometric primitives2
Geometric primitives

  • Conic sections

    • Circles, arcs, ellipses, parabolas and hyperbolas are composed of conic sections

    • Granularity may be important for printing

Image-source: Mathworld.Wolfram.com

Geometric primitives3
Geometric primitives

  • Circle

    • May often be constructed in many different ways:

      • Radius

      • Diameter

      • 3 Points

      • 2 Tangents & radius

      • etc

Geometric primitives4
Geometric primitives

  • Arc

    • Fraction of circle:

      • Can be used to construct complex curvedshapes by composition

Geometric primitives5
Geometric primitives

  • Parametric curves: Bézier spline

    • Historically eldest of the free-form curves with some limitations

    • Control vertices, control polygon

Geometric primitives6
Geometric primitives

  • Parametric curves: B-spline

    • Better control over curve

    • Found in many applications

Geometric primitives7
Geometric primitives

  • Parametric curves: NURBS

    • Non Uniform Rational B-Spline

    • Used by Autocad, most flexible

    • X,Y,Z,W coordinates for control points

Geometric primitives8
Geometric primitives

  • Pattern, hatches, fillings

    • Can only by applied to closed shapes (‘regions’ in ACAD, sort of 2D solids (more later on))

Geometric primitives9
Geometric primitives

  • Pattern, hatches, fillings (continued)

    • Modern applications offer associative fillings

Basic operations
Basic operations

  • Copy

    • Creates one or more copies of a geometry or groups

    • Definition of base point can be used for proper placement

Basic operations1
Basic operations

  • Array copy

    • Multiple copies in rectangular or polar (rotated) series

Basic operations2
Basic operations

  • Mirror

    • Mirror using a mirror axis

Basic operations3
Basic operations

  • Extend

    • Extend lines to arbitrary boundaries

Basic operations4
Basic operations

  • Trim

    • Use arbitrary boundaries to cut away geometry

Basic operations5
Basic operations

  • Break

    • Use two arbitrary boundaries to cut away geometry in-between

Basic operations6
Basic operations

  • Stretch

    • Lengthen/shorten/scale/distort parts of geometries with some parts staying fixed

Coordinate entry acad
Coordinate entry ACAD

  • Directly enter coordinates into the WCS or current UCS by a comma-separated list with arbitrary precision

  • Examples for single points/vertices:1, 2.0, .3relative to last point: @1,2,3.01

Coordinate entry acad1
Coordinate entry ACAD

  • Angular data entry:[Direction] < [Distance]Example: 5 units long line pointing to right in default WCS:90<5.0

Operation and selection
Operation and selection

  • Order of operation in ACAD

    • Most command can either be invoked

      • Verb – object (state operation first and select objects to apply it to later on)

      • Object – verb (Select objects and state which operation to carry out)

    • The default method (if no other command explicitly invoked) in ACAD always is set to selection

Operation and selection1
Operation and selection

  • Selection in ACAD

    • Objects can be selected by

      • Pick single objects in succession (picking them again de-selects them

      • Drag rectangle from up-left to down right to select all objects inside rectangle

      • Drag rectangle form down-right to up-left to select those that are either inside or touched by selection rectangle

Operation and selection2
Operation and selection

  • ‘Transparent’ operations

    • While in the middle of a command sequence, the current command can be suspended for later finish in order to carry out in-between steps

    • Most typical examples are the different viewing command (zoom, pan, change perspective etc)

    • On the command line transparent mode of a command is activated by putting a ‘ in front of the command statement

Visual assistance
Visual assistance

  • Ortho mode: only rectangular movements of mouse possible

  • Snapping: Catch i.e. one of the following points of existing geometry:

    • Endpoint

    • Midpoint

    • Center

    • Tangent

    • Perpendicular

    • Nearest (point on line/curve)

Visual assistance1
Visual assistance

  • OSnap tracking:Visual indication of graphic cursor such as

    • Parallel to existing line

    • Apparent intersection of two lines

    • Point on virtual extension of existing line

  • Grid: Virtual points in drawing space. When put into exclusive Grid-snap mode only these point can be chosen with the pointing device to construct geometry

Structuring drawings
Structuring drawings

  • Color / Line weight / Linetype

    • Historical method

    • Limited to specific set of colors in most applications

    • Might interfere with output needs

    • Colors not always distinguishable very well

Structuring drawings1
Structuring drawings

  • Blocks / groups

    • Complete parts made easily available for reuse

    • Manipulate complex parts applying modifications only to on object

Structuring drawings2
Structuring drawings

  • Layers

    • Easy metaphor for architects (stacked transparent paper)

    • Easy to handle

    • Unlimited granularity

Structuring drawings3
Structuring drawings

  • XRefs / inclusions

    • Drawing split into smaller entities/files which are composed into a single drawing

    • Especially well-suited for group work (different members may simultaneously work on different parts of the building in different files

    • Often problematic when moving to other machines / working environments

Standard exchange formats
Standard exchange formats

  • DWG

    • Proprietary Autodesk format with frequent changes

    • Can be im-/exported by many applications

    • Features advanced geometry (Solids etc.)

    • Can be extended by 3rd party applications

Standard exchange formats1
Standard exchange formats

  • DXF

    • Most established, open standard for data exchange to date, interfaces build into many applications

    • Human readable ASCII format

    • Limited set of geometry and information

    • Only faces/polygons supported

    • No advanced geometry such as solids and NURBS

Standard exchange formats2
Standard exchange formats

  • IFC

    • Developed to suit needs of building industry

    • Open

    • Extendable

    • Lots of advanced meta-data storable

    • Not widely supported (yet/anymore)

    • Under development / constant change

    • XML-version human readable and easy to integrate for collaboration with other applications

Assignment 1
Assignment 1

  • Turn in on 21.03.04 by either creating a webpage and notify me or directly send to (please zip files)j.beetz@bwk.tue.nl

  • Please document your work progress and hand in questions that will be answered in class on Friday

  • If need support also available on ICQ/Yahoo

Assignment 11
Assignment 1

Please check


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