Goals • Give an introduction to the core concepts of parametric CA(A)D and Building Information Modeling (BIM)
After this session you should … • … have basic ideas about the fundamental concepts of Computer Aided Design and Building Information Modeling (BIM) • … be aware of benefits and problems of BIM
Overview • Introduction to CA(A)D and BIM: • The history • why CAD? • The problems • What’s wrong with today’s CAD? • The promises • What can the application of the BIM paradigm do about it? • The real world • what does actually work today?
Overview • Conventional CA(A)D • Parametric modeling • Adaptable geometry • Adaptable representation • Building Information Model • Information Exchange
Communication and Information Exchange Shannons communication model
Means of communication in the AEC domain • Conceptual sketches • Scale models • Oral descriptions (telephone, meeting…) • Written descriptions • Plans, elevations, sections • Details • …
Invention of descriptive geometry • History: • 325 BC–265 BC Euclid The Elements • Inventor of the coordinate system, ‘father’ of geometry
Invention of descriptive geometry • History: • 1435 Leone Battista Alberti De pictura • First scientific work describing central and orthogonal perspective
Invention of projective geometry • History: • 1591-1661 Gérard Desargues • Invention of projective geometry
Invention of the modern CAD concept • History: • 1960 Ivan Sutherland SKETCHPAD • 1982 AutoCAD 1.0 introduced on COMDEX Sketchpad demo
Pierre Bézier [1910-1999] • Invention of parametric curves for the use in computer graphics • UNISURF CAD application devd. for Renault on Bézier-curves in the 1960's • “If your system were that good, the Americans would have invented it first!” (Management of Renault to B. in 1971)
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 • Get rid of paper by electronic documents • Let ‘intelligent’ functionality take care of certain tasks (automation)
CA(A)D packages • The real world: • CA(A)D in most cases used as 2D pen and paper replacement • Document exchange critical due to lack of standards • Applications are error-prone
Nature of the Building and Construction Industry Very fragmented industry • For example, in the EU (statistics 2000): • 11 million jobs, 2 million companies • 93% of companies less than 10 employees • Only 100 companies with more that 2000 employees (source: Arto Kiviniemi)
Chuck Eastman • Building Information Model • "Building information modeling integrates all of the geometric model information, the functional requirements and capabilities, and piece behavior information into a single interrelated description of a building project over its lifecycle. It also includes process information dealing with construction schedules and fabrication processes."
Communication and Knowledge Exchange Now Then?
Building information model paradigm • Building is designed assembling parametric objects that are related to each other • Every object of the building has a set of properties that can be interpreted in different contexts • Geometrical representations (e.g. drawings) are only one of many aspects. Drawings can be generated dynamically from existing data. • Changes to the model are reflected in all depending documents • Different domains (structural engineering, building physics etc.) have different views on a building model
Conventional drawing of a rectangle P1 : x=1, y=1 P2 : x=6, y=1 P3 : x=6, y=4 P4 : x=1, y=4
Parametric drawing of a rectangle Parameters: (input from modeler) Object type : Rectangle Width : 5 Height : 3 Center Point C : x = 3.5 , y = 2.5 Application calculates explicit geometry: P1 = x = x-coordinate of point C – width / 2, y = y-coordinate of point C – height / 2 P2 = x = x-coordinate of point C + width / 2, y = y-coordinate of point C – height / 2 P3 = x = x-coordinate of point C + width / 2, y = y-coordinate of point C + height / 2 P4 = x = x-coordinate of point C - width / 2, y = y-coordinate of point C + height / 2
Non-parametric building elements • Window as non-parametric geometry: • When size of window is manipulated by scaling, the profiles of the window frame are scaled as well • Each part of the frame has to be adjusted • Many operations are necessary => time and errors • Hint: you can actually use “stretching” in a 2D-case to prevent this
Custom parametric objects Circumference = number of chairs x 0 .60cm
Different representations of parametric objects • Low detail 1:100 • Medium detail 1:50 • High Detail 1:50
Conversion 2D -> BIM Model CAD 3D + Facilities Management Electrical domain Collision detection HVAC domain Thermal domain Source: German IAI for building Services BIM
Building information model paradigm • Advantages • ‘intelligent’ applications can gather all sorts of information (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