University of Ljubljana Faculty of Civil and Geodetic Engineering Computer Mediated Communication (CE6014) Modeling method October 2013 Matevž Dolenc matevz.dolenc@gmail.com
When we mean to build, We first survey the plot, then draw the model, And when we see the figure of the house, Then must we rate the cost of the erection, Which if we find outweighs ability, What do we do then but redraw anew the model In fewer offices, or at least desist To build at all? William Shakespeare, King Henry IV Part 2
Outline Definitions Evolution of modeling in construction Foundations of modeling Modeling formalisms and tools Modeling methods
Learning objectives Modeling - Modeling is a key step in creating IT support for a real world problem - Required by all levers of managers and software engineers - Essential activity in human problem solving
Definitions Model - Reproduction of something - Perfect: deserving to be imitating Modeling - A process during which models are created Modeler - A person who is modeling Examples - model railroads, model buildings, finite elements models, etc.
References Books - Eastman, C.M. (1999), Building Product Models, CRC press - Sowa, J.F. (2000), Knowledge representation, Brooks/Cole - Sowa, J.F. (1984), Conceptual Structures: Information Processing in Mind and Machine, Addison Wesley Papers: - Turk, Z., (2001), Phenomelogical Foundations of Conceptual Product Modeling in AEC, http://www.zturk.com/data/works/att/d2df.fulltext.08318.pdf
Evolution of modeling in construction Construction is about big 3D objects Communication is essential - communication through drawings Contributors: - Brunelleschi, 15th century, scaled drawings - Monge, 18th century, projections Exchange of drawings: vital information technology! Drawing is also a model
Drawing with computers Sutherland, 1963, sketchpad PCs, 1980s, AutoCAD Several kinds of drawing programs - The difference is in the elements of which a drawing is composed
Kinds of drawing applications Criteria - Drawing element - Drawing canvas Paint or photo programs - Draw or illustration programs CAD programs - 2D drafting - 3D geometric design - 3D professional design (BIM) - 4D design and planning (BIM 4D)
Paint - Draw - CAD drawing complexity content information
Paint / Photo programs Properties - Entity a pixel - Space is raster, bitmap Examples - PhotoShop - PaintShop Pro - Gimp
Draw or illustration programs Properties - entity is a 2D geometric element, usually with several formatting attributes (color, thickness, pattern...) - space is 2D paper space - precise, scaled drawing not possible Examples - Adobe Illustrator - PowerPoint
CAD programs CAD (Computer Aided Drafting/Design) Properties - entity is a 2,3 or 4D geometric element - 2D, 3D or 4D model space - few formatting attributes - support for precise positioning - scale and measure Examples - AutoCAD - ArchiCAD - zwcad
BIM programs BIM (Building Information Model) Properties - entity is a 3D or 4D building element - 3D or 4D model space - Element attributes - Precise positioning Examples - Revit - ArchiCAD - AllPlan
CAD Drafting applications - 2D entities to be placed into 2D drawing plane. One model one drawing. Geometric design applications - 3D geometric entities (cube, cylinder) placed into 3D space. One 3D model, several projections possible. Specialized design applications - 3D product entities (beam, column, wall) placed into 3D space. One model, several projections. Uses beyond drawing production. Specialized design and planning applications - 3D + time = 4D entities placed in 3D space with construction planning data included
Drawing overview element canvas Paint pixel raster n*m pixels Draw formatted drawing element drawing n*m cm CAD drafting 2D drawing element world coordinate system CAD modeling 3D 3D element, solid, body world coordinate system BIM 4D modeling object from profession (column, window,...) object and processes world coordinate system world coordinate system + time
Lessons about drawings in early 1980 Geometric information should be standardized in order to be exchanged - search for standard formats to encode geometry (DXF, IGES...) Geometric information is important but not enough - e.g. material properties, weights, E modulus, cost, schedule, supplier, contractor, etc. Great interest in modeling since mid 1980s
Model vs. drawing or 3D model Drawing or a 3D model are a kind of abstraction of reality Drawing is special one, dealing with shape and looks only Modeling should be much more generic
Philosophical foundations of modeling How we understand the world around us The meaning triangle Aristotle - things - words - experiences in the psyche OBJECT! Ogden and Richards: - object - symbol - concept CONCEPT! SYMBOL! B-E-A-M
Meaning triangle: object The object is any entity from some real or imagined world about which an idea is held. Example - The beam in the Nada Ward Museum of Modern Art in Kobe damaged by an earthquake OBJECT! CONCEPT! SYMBOL! B-E-A-M
Meaning triangle: symbol The symbol is an auditory, visual, or other form of utterance that is taken to stand for the object when communicated as part of a language Example - beam - column - window CONCEPT! OBJECT! SYMBOL! B-E-A-M
Meaning triangle: concept The concept is the idea or thought of the object as held in the mind of a person. Example - A structural concept of a beam. as illustrated. OBJECT! CONCEPT! SYMBOL! B-E-A-M
Mind and machine It has been suggested that intelligent systems achieve their intelligence by manipulating symbols of real world objects. Humans do it by manipulating "experiences in the psyche", concepts or "mind models". Computers could manipulate symbolic representations of the models. Therefore, computers could achieve intelligence, just as humans do, if only the models and the manipulation rules could be complex enough. Humans are intelligent, because they and computers handle symbols. Sowa, J.F. (1984), Conceptual Structures: Information Processing in Mind and Machine, Addison Wesley
Mental models when we think, we create a model of the messy real world situation we manipulate the model we solve a problem models can be represented as semantic networks
Semantic networks Nodes - concepts wall Arches - relations between concepts has window has door is-an is-an is reduces opening white strength
Reuse of semantic networks Semantic networks - are not built from scratch each time wall Library of semantic networks - Partly populated networks is stored has window has door - A closely matching one is selected and adapted to current problem Frames is-an opening reduces is-an is white - A popular concept in knowledge representation and AI strength
Using semantic networks Repetition, reuse, frames or similar Computer program should be good at helping in several situations Instances - 1:1 mapping to real world problem - this wall in this room Generic concepts - one generic concept corresponds to several real world items - walls in general
Model life cycle Create - Observe real world - Create database schema - Implement database and software Use - Observe real world - Map unique situation into into database schema - Fill database with data - Manipulate, analyze, synthesize model
Layers of model real world conceptualization semantic network roof house wall door window schema model data model
Modeling formalisms and tools Method Language Resources, references Tools - Modeling tool - Development/implementation
Modeling method Break into pieces Reconstruct the whole Method - How to break up - How to put together
Modeling language Language in which models are described Formal language - a language that has a well defined form - Provides a symbolic notation for the concepts being modeled - Computer parseable, based on mathematical logic, textual of graphical Different languages for different model layers and kinds of models - Models of products - Models of processes Examples - EXPRESS, NIAM, IDEF0, XML...
Modeling resources Resources - Building blocks - Relations between them Resources further restrict the perspective on the world
Resource building blocks Subatomic - Number, string of text... Atomic - Entity, object, attribute, type... - Relations, relation types, abstractions Molecular - Reference models - Resource models - Geometric objects, business objects, etc.
Generic relations: abstractions To abstract - to take away Specialization:generalization - A is-of-type B - Wall is-of-type structural element Composition:decomposition - A has-parts B,C,D - Wall has-parts mortar-brick-insulation Characterization - A has-characteristics B,C,D - Wall has thickness, weight...
High level resources: reference models Further narrow down how we may think of the world - The world is made of functional units which are implemented with a technical solution. - Everything has a form, a function, and a behavior. Example: - IFC (Industry Foundation Classes)
Tools Modeling tools - Computer program that allows for modeling - conceptual modeling - schema modeling Implementation tools - Generates database application based on schema - Creates SQL statements based on schema - Creates full application
Summary To deal with complex situations, we simplify them into models Models have many parts which are related to each other Parts should be organized in such a way, that the model can be observed at different levels of abstraction =~ simplification Kinds of abstraction: - type-of / part-of / characteristic Real world > model > schema model > data model Method, language, resources, tools help us but narrow down the kinds of models we can make