6. appendix f - publication · 2006. 3. 26. · 6. appendix f - publication shapes can differ...

6. Appendix F - Publication

6. Appendix F - PublicationThis appendix contains a research paper written by Vinzenz Sedlak and me and presented by me at the conference for “Lightweight Structures in Civil Engineering” in Warsaw in Sept. 2005. The paper was published in the conference proceedings.

The layout has been adjusted to fit the landscape paper format of this thesis.

“Building Shape Ontology” by Philipp Jurewicz F1


1. INTRODUCTION1.1. Lightweight Structures and ShapeThe conceptual design of lightweight structures involves in-depth knowledge of available building shapes and the appropriate means and techniques to translate them into viable structure and building. Choice of building shape is a central aspect of architectural design and often the starting point of interaction between architect and engineer designer.

In order to facilitate choice shape classifications provide useful and essential tools.

During the last decades researchers developed shape classification in form of modules within dedicated online database systems [Sedlak1996] and in form of more general classification systems in print publication [Otto 1988][Critchlow 1969][Gheorghiu 1978].

Each example used the information tools of its time, therefore some shortcoming of the interactivity level can be identified. Also the internal and external interrelationship of data is limited. Internal references between classified shapes require a more complex data layout which wasn't always suitable in earlier years. External references and especially the mapping of classifications from different sources are hard to achieve with traditional information concepts such as print media and databases.

1.2. Aims & MethodThe aim of this research is to provide an interactive shape classification and its online implementation which can complement broader conceptual design/learning resource integration projects like [archistructura Online 2005] and “SDA-(Conceptual) Structures Design Aid” [Sedlak 1996], where a wider range of design aspects of buildings

is investigated. The primary audience for the application will be architecture students involved in design projects

The focus is not to reinvent the wheel but rather try an integration approach that is based on existing classifications and enhance the content only as necessary. By identifying connection points and a possible mapping between examples the new system should gain additional value and serve as a framework for further integration.

The next step is to implement a web application which enables the user to access and browse the domain of building shape over the Internet. Target servers are [sda.fbe.unsw.edu.au Online 2005] and [archistructura.net Online 2005]. The custom needs of the academic concepts behind these project must be taken into account (e.g. multilingual) [Sedlak 1997] [Pfeiffer-Rudy & Jaksch 2004]

Method

Existing sources ([Otto 1988], [Sedlak 1996], [Loh 1990], [Critchlow1969], [Gheorghiu 1978], [Joedicke 1962], [wolfram.com Online 2005] and [maths.org Online 2005]) to building shape were reviewed and the basic organisational layout identified. Connection points and overlapping sections between the approaches were the starting point for a new meta classification. Even though connection points do exist, it became evident that an attempt to unify the approaches could not be achieved with traditional data representation.

Data graphs and knowledge-base concepts arrived from a niche discipline into research mainstream and could possibly overcome the identified drawback of limited cross references of tabular (database) and hierarchical (tree) shape classification.

An attempt was made to apply the “ontology“ idea on abstract building


The conceptual design of lightweight structures involves in-depth knowledge of available building shapes and the appropriate means and techniques to translate them into viable structure and building. Choice of building shape is a central aspect of architectural design and often the starting point of interaction between architect and engineer designer. Existing sources to building shape were reviewed and the basic organisational layout identified. Connection points and overlapping sections between approaches were the starting point for a new meta classification. The principal outcome is a conceptual “shape ontology“ describing building shape in a manner which is human readable and by using semantic mark up also “understandable“ for web applications and knowledge-base software. A web application combines the shape ontology with the 3D models.

key words: Building Shape, Ontology, Web Application, Classification, Visualisation

Building Shape Online - an ontological approach to organization and visualisation

By Philipp Jurewicz cand.arch. and Vinzenz Sedlak Prof. D.I.MPhil

Fig 1: Schemas of Tables (top left), Trees (top right) and Data Graphs


shape knowledge. The resulting classification was checked by applying it to actual building projects and connecting them with abstract (generic) shape information within one dataset. This iterative method resulted in “fine tuning“ of the organisation of abstract (generic) shapes and the whole system became more suitable for use in the context of buildings.

2. DIGITAL DATA CONCEPTS2.1. Data modelsDomain experts commonly work with structured information which is organised in either tabular, hierarchical or data graph form. Each of these have advantages and disadvantages and the following section gives a brief overview.

Data tables arrange data in columns for each variable and rows for each data set. Their organisational focus is to query rows with e. g. similar, ascending or descending variables. The connection of tables makes a database relational and is depicted by database schemas. A drawback of simple tables is that all data sets consist of all variables even when some variables are not logically necessary for each data set.

Hierarchical data organisation can be depicted as a tree diagram and follows the idea that one member is a sub classification of an other. A disadvantage is the strict focus on only one parent-child relationship, which can lead to repeating sub branches that can bloat the tree and makes it hard to maintain. Stricter managed representation of hierarchies are known as taxonomies and thesauri.

Data graphs are related to hierarchies but one important difference is that they allow directed and undirected connection between the nodes which can be depicted in node-and-edge diagrams. It is also possible to have more then one superclass for a specific member and it is not necessary to have a root object. The current drawbacks of data graphs are that they require more computing logic to handle its features (e. g. the possible cycles/loops in a path) and common users are not necessary familiar with these organisation. Even though the World Wide Web “browsing experience” follows a similar pattern.

2.2. OntologyThe term ontology is borrowed from philosophy broadly defined as „a particular theory about the nature of being or the kinds of existent” [Merriam-Webster Online 2005] . In computer science the definition is slightly more narrow.

A body of formally represented knowledge is based on a conceptualization: the objects, concepts, and other entities that are assumed to exist in some area of interest and the relationships that hold among them (Genesereth & Nilsson, 1987) . A conceptualization is

an abstract, simplified view of the world that we wish to represent for some purpose. Every knowledge base, knowledge-based system, or knowledge-level agent is committed to some conceptualization, explicitly or implicitly.An ontology is an explicit specification of a conceptualization.[Gruber 1993]

Ontologies often use taxonomies as their backbone but they enhance them by adding the advantages of data graphs. While thesauri organise terms, ontologies also try to describe the meaning of a “thing” within its context by using constrains and advanced links (called “properties”). The interrelationship between information is therefore more emphasised than in databases and taxonomies/thesauri. In its final stage an ontology represents a “Local Domain Theory” which is consistent, human readable, machine interpretable and can be used to further infer relations.[Noy & McGuinness 2001] [Daconta, Obrst & Smith 2003]

Main parts of ontologies are

Individuals [/items], represent objects in the domain that we are interested in, also known as the domain of discourse. [Horridge 2004]

Properties are binary relations on individuals [/items]. A binary relation is a relation between two things. [Horridge 2004]

Classes are interpreted as sets that contain individuals [/items]. They are described using formal (mathematical) descriptions that state precisely the requirements for membership of the class. [Horridge2004]

As the main audience for this project is not likely to be familiar with knowledge base terminology the term „individual“ will be substituted it with the word „item“.

3. BUILDING SHAPE ONTOLOGY3.1. Basic classification of shapeWhile most shape classifications can be represented in taxonomies/thesauri as separate entities the attempt to unite them into a single taxonomy lead to difficulties because the basic underlying axiom which is the driver for the question: “what makes one class a subclass of another one?” differs between the classifications. For instance a more general classification [Otto 1988] uses a recursive zoom model which also utilises perception and surface characteristics, while a more specific polyhedral classification [Critchlow 1969] follows strict geometric parameters. Even within the geometry domain the classification of


Fig 3: A: Main classes of the surface typology; B: deep branching; C: consistent sub branching; D: multiple characteristics.

Fig 2: A Truncated Cone as Solid and Surface Geometry


shapes can differ significantly: solid body geometry can define “cone” in a different way than surface geometry (see Fig. 2).

Real buildings are often arrangements of more than one type of shape and therefore identification of the different levels is helpful. This paper follows the definition in [Sedlak 1986] and [Loh 1990]: “Units” describe the basic shapes like prism, cone, pyramid, etc. and shapes that can not be subdivided without loosing their key characteristics. “Aggregates” contain two or more units. The term “Composites” covers even bigger arrangements of multiple aggregates and units.

These statements leads to the main organisation of the conceptual “shape ontology”. The domain of building shape can be separated into three main parts: typology shape, catalogue shape and project shape.

3.2. Typology shapeA (shape) typology is a well defined, consistent and closed set of data that is organised by hierarchical/taxonomic relations and graphs with the focus on one aspect of shape.

Typologies can describe the same visible shape in very different ways (f. i. solid body geometry vs. surface geometry, Fig. 2) with their own set of rules. It is legitimate to have more than one definition of a shape in the ontology as long as the particular definitions are consistent within their own typologies.

Typology items are distinct single entities and therefore shape units. Shapes that are aggregates and composites are usually not typology shapes.

Typology items can/should refer to other typology items with properties such as „see also“ „is defined by“ „has typology“ etc.

3.3. Catalogue shapeA (shape) catalogue is a collection of possible building shapes focusing on specific aspects. Catalogues serve a purpose. The internal classes, items and properties of catalogues have a layout for a specific task such as timber construction, membrane structures or social aspects of buildings etc. .

Catalogues can be assembled with a specific set of projects in mind. This is legitimate because catalogues are not claiming to be complete and exhaustive collections they are rather purpose driven.

Catalogue items can be assembled/subdivided into units and aggregates.

Catalogue items are connected to typology items with strong and detailed properties like “has Geometry 3D”, “has Arrangement” and “has Proportion”. Because typologies are closed, consistent and therefore less likely to change. Typology items are defining catalogue items.

3.4. Project shapeProject shape is the external appearance of a real building. As buildings can be quite complex, the shapes can be subdivided into composites, aggregates and units.

Project shape can be weighted. In order to indicate dominant shapes according to the design intend the ontology defined “primary” and “secondary” properties.

Project items can refer to catalogue and typology items with the properties “has Primary Catalogue Shape”, “has Secondary Catalogue Shape”, “has Primary Typology Shape” and “has Secondary Typology Shape”. Often a related catalogue item is available but the project shape does not match exactly this generic shape. The user can then connect the catalogue item and add typology items to “annotate” this link. If no matching catalogue item can be found the user can use exclusively typology items to describe the shape. (see Fig.6)

4. TYPOLOGIES4.1. Incorporated typologiesShape typologies for the recognition of external building shape can be divided into a general and a geometrical group. General typologies try to describe shape in a descriptive and generic way. Geometrical typologies follow mathematical rules and their items are determined by their “geometric properties” (e. g. the number of sides in a prism).

Currently the following general typologies are incorporated:

• Arrangement – Information about Axis, Orientation, Spacing and Symmetry.

• Proportion – Principal extension of shape objects: one-dimensional, two-dimensional or three-dimensional [Sedlak 1986]

• Surface – Information about Curvature, Edge, Surface Point, Undulation. [Otto 1988]

• Truncation – Information on modification (truncated / cut / reduced / trimmed shape).

Currently the following geometrical typologies are incorporated:

• 2D Geometry – Information about open and closed curves, polygons and angles. Thesaurus from [maths.org Online 2005]

• 3D Geometry is subdivided into two.

• 3D Solid Geometry refer to volumes. Prominent subgroups are the Prisms, other Polyhedra, Geodesics, etc. . [Critchlow 1969]


Fig 5: Members of the SDA Shape catalogue class "Cone"

Fig 4: A "prism" as super class of a "right prism" which again is super class of a "regular prism"


[wolfram.com Online 2005] [maths.org Online 2005]

• 3D Surface Geometry refers to surfaces, often defined by curves in space (e.g. transition, revolution, helical, minimal surfaces). [Gheorghiu 1978] [Joedicke 1962]

4.2. Internal organisation of typologiesTypology items are the more closer defined the deeper they are located in a hierarchy: f. i. a “square” is a special case of a “rectangle”, which is a special case of a “rhomb” etc. . Figure 3B shows that this approach can lead to deep hierarchies. They have the advantage that a computer can infer that projects with a rhombic ground plan have more similarities with building projects that have a square plan than the one with a circular plan.

A further advantage is that catalogue items and projects can be tagged even when the editor is uncertain about a topic: e. g. within the variety of geodesic polyhedra it is possible to classify a project as „a kind of geodesic polyhedron“. Other projects can be classified as „frequency 6 icosahedron“ and are still related to the first project because their class is a subclass of the general class „geodesic polyhedron“.

Subclasses should always follow the same pattern within their main branch and not mix aspects: e. g. the 90 degree angle which is used in most buildings can be the driving characteristic for the definition of subclasses. Figure 4 and Fig. 3C show the “snapping“ of a present angle in the more general super class “Prism” to 90 degree in the subclass “Prism Right”. This is a common pattern in the ontology.

All typology classes have a default item. If an editor is not sure about further details of a project he/she can refer to this default item. Sibling items can be added when necessary. They represent variations within the characteristic of the class. Where variations are repetitive and well structured they are regrouped into subclasses with their own default items. (see Fig. 3D)

5. CATALOGUESThe present stage only one catalogue is implemented, further potential catalogues are listed in chapter 8.2.

The SDA Shape Database table [Sedlak 1996] is implemented as the “SDA Building Shape Catalogue”. It was created to assist the identification of lightweight structures and is part of a database system which investigates application, structure, shape, cladding and project.

The organisational layout of the SDA Shape table is based on solid geometry: Cone, Cylinder, Polyhedron, Prism and Pyramid form the main branching. They are accompanied by Dome and Vault which are,

strictly speaking, not geometrical types but building types. Dome and Vault connect with shape typology items because most of their items can be described as truncated spheres and cylinders.

Because the SDA Shape data is interpreted as a catalogue it can follow a pragmatic organisation which suits the investigation of lightweight structures: e. g. the catalogue adds items to it's Cone class which can not be defined with solid body geometry nor with surface geometry as cones (see Fig. 5). Instead the perceived shape of the building envelope is matched with existing principal shape types.

6. TEST CASESExample of building project illustrate the working of the shape ontology by connecting with catalogue and typology shapes. This also results in iterative “fine tuning” of the system.

Figure 6 show how the Japanese Pavilion on the Expo 2000 Hannover is classified. First the project shape is connected to two catalogue shapes (1). These catalogue shapes themselves are defined by typology shapes from various typologies (2)(3)(4)(5). The editor finds further significant characteristics in the projects and connects the project shape directly with typology shapes (5)(6)(7). Now the software can infer that the shape of the Japanese Pavilion is related to other project shapes (8)(9)(10).

7. INFORMATION TECHNOLOGY7.1. The ontology applicationThe editor software for the shape ontology is “Protégé” [stanford.eduOnline 2005]. Protégé is a rich desktop application with a strong academic user base and is actively developed under an open source license.

7.2.The web applicationThe Internet changes the way we “navigate“ through data. The Hyperlink can alter the context of information with a mouse click and is well understood among expert and lay users.

Interactive user interfaces, multimedia capability and the possibility to update information on an ongoing basis are characteristics that the proposed web application aims to utilise.

The technological infrastructure for the web application can be summarised as a Java environment with an Apache Tomcat server [apache.org Online 2005]. The application itself is built upon the Spring Framework [springframework.org Online 2005] and the Jena Semantic Web Framework [hpl.hp.com Online 2005]


Fig 6: Japanese Pavilion and its referenced shape information


The site aims to encourage architecture student to explore building shape Real building projects serve as starting point.

Consistent colour coding is used: Red is associated with project shape, green with catalogue shape and blue with typology shape (see Fig. 6 & 7)

At the state of writing this paper the web application is not yet open to the public. Please contact the authors for access to the preview website.

8. SUMMARY AND CONCLUSION8.1. SummaryThe principal outcome of this project is a conceptual “shape ontology“ describing building shape in a manner which is human readable and by using semantic mark up it is also “understandable“ for knowledge-base software and web applications. Utilising current technology standards it can be imported directly in other ontologies or it can be transformed into custom data formats.

A collection of 3D models and renderings of shapes accompanies the text-based shape-ontology. Spatial models of a shape can be altered, morphed or viewed from another virtual camera perspective to emphasise different aspects of the model. The 3D models serve as a uniform shape library and a further integration into 3D visualising projects is possible.

The web application combines the shape ontology with the 3D models by utilising the multi media possibilities of the Internet.

8.2. ConclusionsThe integrative approach introduced in this paper enabled us to reuse valuable resources without breaking up their own consistency. A significant amount of computer science research was required and seems to open up a promising interdisciplinary field.

Further development should include:

Shape Ontology – The consistent mapping of different shape classification proved to be tedious and needs further attention. By adding more real world building projects the whole typology could be further fine tuned. Shapes of internal spaces could be integrated. New shape catalogues could cover topics like “Membrane”, “Plan View”, “Cross Section”, “Social Profiles”[Pfeiffer-Rudy 2005], [Joedicke 1977] etc. . Further shape typologies such as “Super formula”, “NURBS” and “Subdivision Surfaces” need to be evaluated. The possibilities of ontologies and semantic web go beyond the implemented state and could further be researched and applied.

Visualisation – Integration of structures emphasised visualisation would

integrate the shape ontology tighter into [archistructura Online 2005]

Web application – Additional “perspectives” like taxonomic trees and better full text search capabilities would improve the user experience.

Further research could use the building shape ontology introduced in this paper as a base for a broader architectural shape ontology.

ACKNOWLEDGEMENTSThe authors acknowledge the support from Wolfgang Winter, Margit Pfeiffer-Rudy, Stefan Jaksch (all Institute of Architectural Sciences, Structural Design and Timber Engineering, Vienna University of Technology), Graham Bell and Peter Graham (all Faculty of the Built Environment, University of New South Wales).

REFERENCES[Sedlak 1996] Vinzenz Sedlak "Structures Design Aid Database" Lightweight Structures Research Unit 1996-2001, Faculty of the Built Environment 2001-2005, University of New South Wales, Sydney, 1996-2005 (Online) http://emulava.fbe.unsw.edu.au:8080/

[Otto 1988] Frei Otto "IL 22 Form" Stuttgart, Karl Krämer Verlag, 1988

[Critchlow 1969] Keith Critchlow "Order in Space" London, Thames and Hudson, 1969

[Gheorghiu 1978] Adrian Gheorghiu, Virgil Dragomir "Geometry of Structural Forms" Barking, Applied Science Publishers Ltd., 1978

[archistructura Online 2005] "archistructura" Institute of Architectural Sciences, Structural Design and Timber Engineering, Vienna University of Technology, May, 2005 (Online) http://www.archistructura.net

[Sedlak 1997] Vinzenz Sedlak "A Computer-Aided Conceptual Structural Design Aid" in Proc. 1997 IASS Symposium, 9-14 Nov 1997, pages 745-754, Singapore, CI-Premier Pte Ltd., 1997

[Pfeiffer-Rudy & Jaksch 2004] Margit Pfeiffer-Rudy & Stefan Jaksch "Building Science by Design" in ED-MEDIA 2004: World Conference on Educational Multimedia, Hypermedia & Telecommunications, pages 4815-4820, Norfolk (VA), Association for Advanced Computing in Education, 2004

[Loh 1990] Seok Kuan Loh "Vocabulary of Shape and Structure Type (research report)" LSRU, Faculty of Architecture, University of New South Wales, 1990

[Joedicke 1962] Jürgen Joedicke, Walter Bauersfeld, Herbert Kupfer "Schalenbau -- Dokumente der modernen Architektur, Band 2" Stuttgart, Karl Krämer Verlag, 1962


Fig 7: Typical view of the web application

Fig 8: Screen organisation of the web application


[wolfram.com Online 2005] Eric W. Weisstein "Mathworld -- A Wolfram Web Resource" , May, 2005 (Online) http://mathworld.wolfram.com

[maths.org Online 2005] "Connecting Mathematics" University of Cambridge and Partners, May, 2005 (Online) http://thesaurus.maths.org

[Merriam-Webster Online 2005] "Merriam-Webster Online" Merriam-Webster, Incorporated, March, 2005 (Online) http://www.m-w.com

[Gruber 1993] Tom R Gruber "What is an Ontology?" Standford Knowledge Systems, AI Laboratory, , 1993 (Online)

[Noy & McGuinness 2001] Natalya F. Noy & Deborah L. McGuinness "Ontology Development 101: A Guide to Creating Your First Ontology" Knowledge Systems Laboratory, Stanford University, March, 2001 (Online) http://protege.stanford.edu/publications/ontology_development/ontology101-noy-mcguinness.html

[Daconta, Obrst & Smith 2003] Michael C. Daconta, Leo J. Obrst & Kevin T. Smith "The Semantic Web, Chapter 8" Indianapolis, Wiley, 2003

[Horridge 2004] Matthew Horridge "Protégé OWL Tutorial" Collaborative Open Ontology Development Environment (CO-ODE), August, 2004 (Online) http://www.co-ode.org/resources/tutorials/ProtegeOWLTutorial.pdf

[Sedlak 1986] Vinzenz Sedlak "The Morphology of Structure" in Proceedings LSA'86 First International Conference on Lightweight Structures in Architecture, pages 1164-1187, Sydney, Unisearch Limited, The University of New South Wales, 1986

[stanford.edu Online 2005] "Protégé" Stanford Medical Informatics, Stanford University, May, 2005 (Online) http://stanford.protege.edu

[apache.org Online 2005] "Apache Jakarta Project" Apache Software Foundation, May, 2005 (Online) http://jakarta.apache.org

[springframework.org Online 2005] "Spring Framework" annon., May, 2005 (Online) http://www.springframework.org

[hpl.hp.com Online 2005] "Jena Semantic Web Framework" Hewlett Packard Labs, May, 2005 (Online) http://www.hpl.hp.com/semweb/jena.htm

[Pfeiffer-Rudy 2005] Margit Pfeiffer-Rudy "Semantic Differentials Analysis in Architectural Education" in ED-MEDIA 2005: World Conference on Educational Multimedia, Hypermedia & Telecommunications, pages , Montréal, Association for Advanced Computing in Education, 2005

[Joedicke 1977] Jürgen Joedicke, Heinz Direwanger, E. Geisler & V. Magnago-Lampugnani "Zur Gestaltung weitgespannter Flächentragwerke - Das CEMAG-Verfahren als Entwurfshilfe (research report)" , Special Task Area 64, TU-Stuttgart, 1977

FULL AUTHORS ADDRESSPhilipp Jurewicz cand.arch - Research Assistant, Institut für Architekturwissenschaften Tragwerksplanung und Ingenieurholzbau, Technische Universität Wien, Karlsplatz 13 1040 Wien Austria, Email [email protected]

Vinzenz Sedlak Prof. D.I.MPhil - Visiting Professor, Institut für Architekturwissenschaften, Tragwerksplanung und Ingenieurholzbau, Technische Universität Wien, Karlsplatz 13 1040 Wien Austria, Former Associate Professor and Director, Lightweight Structures Research Unit, The University of New South Wales Sydney Australia, Email [email protected]


mailto:[email protected]:[email protected]

Building Shape Online - an ontological approach to organization and visualisation1. Introduction1.1. Lightweight Structures and Shape1.2. Aims & Method

2. Digital Data Concepts2.1. Data models2.2. Ontology

3. Building Shape ONTOLOGY3.1. Basic classification of shape3.2. Typology shape3.3. Catalogue shape3.4. Project shape

4. Typologies4.1. Incorporated typologies4.2. Internal organisation of typologies

5. Catalogues6. Test cases7. Information Technology7.1. The ontology application7.2.The web application

8. Summary AND Conclusion8.1. Summary8.2. Conclusions

ACKNOWLEDGEMENTSReferencesFull authors address

6. appendix f - publication · 2006. 3. 26. · 6. appendix f - publication shapes can differ...

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