Automation in Construction 10 2001 217–228 Ž .
www.elsevier.comrlocaterautcon
Shared virtual reality for design and management:
the Porta Susa project 1
Luca Caneparo)
Design Network Lab, Dipartimento di Progettazione architettonica, Politecnico di Torino, ˝.le Mattioli 39, I 10125 Turin, Italy
Abstract
The paper presents the implementation of a system of Shared Virtual Reality SVR in Internet applied to a large-scale Ž .
project. The applications of SVR to architectural and urban design are presented in the context of a real project, the new
railway junction of Porta Susa and the surrounding urban area in the city centre of Turin, Italy. SVR differs from Virtual
Reality VR in that the experience of virtual spaces is no longer individual, but rather shared across the Internet with other Ž .
users simultaneously connected. SVR offers an effective approach to Construction Data Model and Computer Supported
Collaborative Work, because it integrates both the communicative tools to improve collaboration and the distributed
environment to process information across the networks. q 2001 Elsevier Science B.V. All rights reserved.
Keywords: Virtual reality; Virtual prototyping; Concurrent engineering; Computer supported collaborative work; Product data model
1. Introduction to shared virtual reality
In 1997 our group at the Department of Architectural Design, School of Architecture, Polytechnic of
Turin, the Design Network Lab, 2 completed the
application of an information system to support the
design and management of a large-scale projects.
The project concerns a central part of Turin, the
new intermodal transport system of Porta Susa and
the surrounding urban area. The new Porta Susa
railway station is fast becoming the fulcrum of an
overall exchange system between high-speed and
) E-mail: [email protected]
1
The article is based on the paper presented by the author at
the CAAD Futures Conference 1997.
2
The scientific heads of the Laboratory are Prof. Anna Maria
Zorgno and Prof. Pio Luigi Brusasco.
local trains, surface transport, both public and private, and the future underground.
The information system was the work environment implemented to support the comprehensive analytical, planning, design, constructive and managing
aspects of the Porta Susa project.
The implementation was based on the shared
virtual environment technology. Shared Virtual Reality SVR integrated and coordinated the work of the Ž .
public administration, the contractors, the firms, the
suppliers, the building companies, and others involved. Capillary and precise communication implied more effective organisation of the overall project through more efficient access and sharing of
information between individuals, groups and organisations 1–4 . Besides ‘‘professionals’’, a further w x
main aim of the SVR was communication and interaction with public transport users and citizens.
0926-5805r01r$ – see front matter q 2001 Elsevier Science B.V. All rights reserved.
PII: S0926-5805 99 00032-1 Ž .
218 L. CaneparorAutomation in Construction 10 2001 217–228 ( )
1.1. Introduction to the Porta Susa project
The Porta Susa project is a major and long-term
investment of the Municipality and the State Railway. The value of the works is 300 million Euro.
The Porta Susa project, also defined as ‘‘Spina’’,
Žis going not only to change a central urban area Fig..
1 , but also to renew the overall system of communications of the city towards an integrated system of
exchange between different means of transport. The
present main railway station, Porta Nuova, is not
suitable for high-speed trains because it is a railhead,
like most of 19th and 20th century central stations.
The project is increasing the importance of the
Porta Susa railway station as the lines will be
quadrupled and moved underground. The Porta Susa
area is becoming the fulcrum of the integrated system of exchange between trains and aeroplanes by
means of a direct train link to the airport, and
between the future underground and the private and
public surface transport. To provide for these increasing requests and functions, a new railway station will be built at the lowered track level, a few
hundreds meters away from the actual one.
Due to the roofing of the lines, the area, no longer
occupied by the railway junction, is available for
new purposes and activities. A result is a spacious
boulevard, which joins two separated parts of the
city.
1.2. Commitments of the information system
The information on the Spina project is made up
of thousands of documents: 3500 drafts and
blueprints; 10,000 pages of reports and technical
specifications; 2400 registered letters; plus drawings,
manuals etc. This huge body of documents was
created and updated by the large number of people
from all fields working on the project.
The information system is the environment committed to improving the work of documenting the
project and to facilitate the various tasks which as a
whole constitute the information-work: storing, retrieving, sharing, adding, modifying and managing
documents.
As considered in a previous paper 5 , the main w x
commitments to the information system are disFig. 1. The Porta Susa area.
L. CaneparorAutomation in Construction 10 2001 217–228 ( ) 219
tributed access, flexibility, scalability and simplicity
of use.
fl The distributed access permits every firm, contractor, supplier and other trading partner to store
information on their servers. Meanwhile the users
can access the overall information in a transparent
way, and are no longer required to know if a document resides locally or remotely. For example, a user
can visualise a drawing or a report consisting of
parts residing on various servers. Download–upload
changes the meaning, the users can browse documents and drawings as if the local disks are a Web
site or explore Web sites as if they are local disks.
The overall documentation of the project is locationindependent and so, thanks to Turin’s fibre-optic
Intranet, the access of a remote server could be as
efficient as a local one.
fl Flexibility is the capacity to work with the
presently used formats of documents, as well as with
futures ones, not yet foreseen in the current implementation. Flexibility in the processing of different
formats of document is obtained by means of the
Multipurpose Internet Mail Extension MIME of the Ž .
Web, which allows the processing of various document formats, hence not only HTML documents.
This potentiality of the HTTP protocol allows one to
associate to each specific type of document the
application necessary to visualise, modify, print or
save it. Flexibility is understood, as well, as the
capacity to dynamically redefine working-groups according to the ongoing task. Flexible definition of
work groups requires not only more efficient communication, but also tools to support dynamic redefinition of the information flows.
fl The scalability is the possibility of integrating
further individuals or groups into the project, dealing
with their computer systems and networks. This
should be made possible, either for the entire time of
the project or, instead, for a limited time, e.g., to
gather specific know-how.
fl Effective simplicity of use comes from the
machine understanding what the user wants to do.
Most programs presently available do not take into
consideration real human functions, but instead offer
tools to automate the information work to certain
degree. What we tried to do with the Porta Susa
information system was to integrate the tools the
users were familiar with, in a networking-distributed
environment. Simplicity of use derives from the
Žintegration of the different applications CAD, word.
processor, spread sheet, etc. with the Web browser.
This is particularly true with the recent applications
conceived to be integrated in an Internet–Intranet
environment. The Web browser can automatically
load the plug-in or the program associated to the
format of the specific document. Today’s graphic
and multitasking OSes allow one to create an integrated and coherent system around the Web browser,
in which the user is no longer required to know
about the compatibility of formats and of the corresponding programs. A further key to simplicity of
use derives from the intelligible organisation of the
thousands of documents produced by the project. In
early system design, the intelligible organisation was
based on global coherence among the documents 7 , w x
achieved by means of the definition of uniform and
common criteria for the creation and storage of the
documents. The Porta Susa implementation experiments with another approach, focused on shared
virtual environment technology.
2. Virtual reality
Virtual reality VR is more than just a further Ž .
three-dimensional representation. Because of the
computer interactivity it permits users to enter and
explore complex data through a spatial representation 8 . VR differs from animation in that the user is w x
actively involved: the user can move — walk in or
fly through — the virtual model, the movement is
unconstrained, i.e., no predefined path exists. VR
feeds the senses vision, hearing and touch with a Ž .
simulated experience of exploring space. The exploration of space is one of the innate aptitudes of
human beings 9 . This is why most people consider w x
VR to be an intuitive medium.
Table 1
Paradigm shift in data representation and information access

Interaction Read and type Draw and click Model and navigate
220 L. CaneparorAutomation in Construction 10 2001 217–228 ( )
Fig. 2. Avatars meeting in cyberspace.
VR could deliver a paradigm shift in data representation and information access Table 1 , from 2D Ž .
graphics to 3D representation, from window based
interaction to space exploration.
In the Porta Susa project not only designs and
prototypes, but the whole documentation is accessible by means of VR. Through Internet the numerous
and various participants in the project have the immediate opportunity to inspect the work in progress.
CAD 3D models are converted to Virtual Reality
Modelling Language VRML and then uploaded to Ž .
the server. Several programs and plug-ins for WWW
browsers are available to explore VRML models.
Since the conversion from CAD to VRML models is
automatic, the representations accessible through the
Internet are easily kept in sync with the design at its
current stage.
Spatial representation is crucial for exploring architecture and buildings, but VR should not be limited to this task. VR enhances the understanding of
interference between flows of different transport systems, e.g., passengers of the high-speed trains, local
trains and underground. VR improves the storage of
a single document among the several thousands of
the overall project and then its easy retrieval by
‘‘walking in’’ a 3D representation of the project with
the relevant documents associated to the construction
objects and buildings.
3. Shared virtual reality
The exploration and critique of a VR model across
the net is essentially an individual process, because
each person, independently from others, downloads
the model and examines it. SVR differs from VR in
that the experience of 3D spaces and objects is no
longer individual, but rather is shared among several
users across the Internet. SVR opens ˝irtual places
in Internet, cyberspaces 3, where people can enter,
meet and communicate with others connected simultaneously.
SVR produces a further paradigm shift merging
the capacity of network communication with threedimensional representation. As a˝atars 4 people can
meet in virtual spaces representing any physical or
symbolic places whatever Fig. 2 . Ž .
SVR is a new medium, a different way to achieve
real-time 3D interaction, different from the Web
wheel of authoring–publishing–browsing pages.
For architects and planners SVR means a new
way to communicate their ideas, to broadcast a
design cf. Section 4.4 , to meet clients and contrac- Ž .
tors directly in the 3D model. As soon as early stages
of the design are modelled, they can be explored and
discussed making everyone feel at home, even if
they are sited in front of a computer at the office.
Virtual tours and meetings about the project can be
arranged to consider ongoing problems and decisions
3 According to the definition of William Gibson 10 , cy- w x
berspace is the total digital network, a place of meeting and
communication.
4
In Hinduism an avatar is the Terrestrial incarnation of a god
or goddess. In SVR an avatar is the user ‘‘incarnation’’ in
cyberspace.
L. CaneparorAutomation in Construction 10 2001 217–228 ( ) 221
among small or large groups. Virtual meetings can
be scheduled in advance or, instead, arranged ad-hoc
among people working on the same task.
3.1. Shared ˝irtual reality plug-in
The tool to gain access through the Internet to
SVR is a plug-in for the main WWW browsers. The
plug-in allows users to explore three-dimensional
scenes by means of the Virtual Reality Modelling
Language VRML . Ž . 5
The plug-in is automatically loaded when the
HTTP protocol defines the corresponding 3D format.
To the WWW browser the plug-in adds the tools for
exploring 3D space, for visualising other users who
are simultaneously connected and for communicating
with them.
At present the plug-in runs with Windows 95, 98
and NT on Intel CPUs.
3.2. Exploring spaces
Moving a virtual observer controls exploration of
virtual spaces and designs. The user defines the
virtual observer’s movements: it is an important
aspect of VR interaction. The method of interaction
depends on the available hardware. With two-dimensional devices e.g., mouse, trackball the user de- Ž .
fines a plane on which, by means of the pointing
device, srhe traces and modifies on the screen a
vector defining the path of the observer in the envi-
Žronment. With three-dimensional devices e.g.,.
spaceball the user gains continuous control of the
movements in 3D.
The SVR plug-in simulates the physical properties
of objects, for example, it does not permit one to
pass through objects, and the movements of the
observer are restricted according to physical laws
such as acceleration and gravity. The simulation of
these properties slows down the interaction with the
world considerably, in that a powerful CPU and a 3D
graphics accelerator card considerably improves
smooth movements and interaction feedback.
5
For VRML specification, see http:rrwww.vrml.orgr.
3.3. Data format of SVR
The SVR plug-in adopts the Virtual Reality Modelling Language VRML , version 2. The VRML is Ž . 6
a file format for describing three-dimensional interactive worlds and objects, conceived to be used in
conjunction with the WWW. Since May 1997 the
VRML is recognised as an ISO standard, and defines
a worldwide accepted language.
In essence, the VRML is a plain ASCII language
to describe 3D worlds. As HTML is a language to
format documents for the Web, VRML is a language
to create spaces and objects. Interpreters browsers Ž .
for VRML are widely available from several companies and institutions for many different platforms.
VRML defines the syntax to describe a scene,
consisting of lights, shapes and their properties. The
properties attributed to shapes are colour, texture,
animation and hyper-links to HTTP documents in
Internet. Version 2 adds the possibility of animating
objects, and improving VR worlds with sounds and
the visibility option, that is fog.
The SVR plug-in implements the VRML 2’s
multi-user capacities and makes use of Javae programming.
3.4. Multi-user
Multi-user capacity is inherent to the nature of
VRML. The SVR plug-in implements several options to make VRML worlds effective cyberspace
communities of people across the Internet. To gain
access to a SVR world the user has simply to follow
the appropriate link from herrhis WWW browser.
After a while depending on the size of the model Ž .
the user will be projected into the shared virtual
reality world.
After the user has selected from herrhis WWW
browser the link to an SVR world, the WWW server
defines the MIME type that the Web browser associates to the SVR plug-in. The Web browser loads the
plug-in and transfers to it the address of the VRML
model to be downloaded. The plug-in downloads and
6
For VRML version 2 specification, see http:rrwww.
vrml.orgrVRML2.0r. For VRML97 ISO Ž . rIEC 14772-1:1997 ,
see http:rrwww.vrml.orgrVRML97r.
222 L. CaneparorAutomation in Construction 10 2001 217–228 ( )
Fig. 3. Chat active among users simultaneously connected.
interprets the VRML language in a virtual 3D world.
If the world contains the definition of a SVR server,
the plug-in loads the multi-user module. The multiuser module is the client, which requests, over the
net, the defined SVR server. The reply from the SVR
server specifies the number and position of the other
users connected. If there are other users in a defined
aura 7 of interaction, the plug-in downloads from the
WWW server the geometry and description of the
appropriate avatar. After the download is completed,
the avatar is displayed in the proper position, while
the plug-in regularly transmits the position of the
user and in the meanwhile receives the positions of
the other users.
3.5. Communication in SVR world
The multi-user module integrates a chat program.
The chat allows people in SVR worlds to exchange
brief written messages. The plug-in forwards the
7
The aura is the predefinible radius of visibility and interaction
among avatars.
message to the SVR server, which redistributes it to
every user connected Fig. 3 . SVR and written chat Ž .
require really modest Internet bandwidth and so they
perform well at 28 k on telephone lines.
Development is focused on vocal messages, which
assures more friendly communication. A main drawback of vocal messages is that the communication is
not full duplex, because a certain time lapse between
the submission and the reception exists, and single
packets can arrive delayed or out of sequence. Individuals in wide spread groups can receive the message at different moments, making effective interaction difficult.
The integration of the SVR plug-in with the main
WWW browsers permits one to use other tools of
communication. To gain audio capacity, RealAudioe or a conference program can run concurrently
with the SVR plug-in.
The avatar has a limited capability to use ‘‘body
language’’. For instance, the user can raise the
avatar’s virtual arm Fig. 3 or shake the virtual Ž .
hand. To change the avatar’s posture, to the interface
are added buttons, which activates Java scripts.
L. CaneparorAutomation in Construction 10 2001 217–228 ( ) 223
3.6. Interacti˝ity
Javae adds further action to VRML worlds. Java
scripts can be attached to polygons and objects in
order to perform specific actions based on events,
temporal change or the user’s interaction. For instance, it is possible to use a wall of a building as a
blackboard or sketch book, or to define an interactive
environment in order to assemble objects from primitive solids. There is almost no intrinsic limit to what
imagination can bring in a VRML environment by
means of Java programming.
Simple but effective ways of interactions allow
users to pick a cab or a bus and to drive around with
them. It is possible to use a wall of a building as a
blackboard or sketchbook. Advanced techniques are
used to create or modify VRML models according to
user’s requirements. It is possible to create an interactive environment to assemble objects from primitive solids or to allow the user to increase the green
areas inside the project by pulling icons into the
appropriate areas. The system considers the user’s
new requirements, and reduces the amount of other
functions, such as parking or commerce, in conformity with the regulatory plan. The VRML model is
updated according to the new user’s defined requirements so that srhe can explore the new urban layout
and, eventually, further interact with and modify it.
4. Design and management applications
4.1. Shared ˝irtual prototypes
One of the early aims of VRML is the sharing of
three-dimensional models across the net. For architects, engineers and planners VRML makes it possible to share models on the basis of a platform
independent standard. No matter what the CAD and
modeller programs are used, the model can be exported to the VRML format and shared across Internet.
Buildings, structures, infrastructures can be closely
examined before they are built 11–13 . The differ- w x
ent participants in the project can explore design and
technological solutions in depth and in detail by
walking in and flying through. The ability to explore
the model is important in order to examine the
interrelations between the parts. The use of colours
can produce either realistic representation, for example to evaluate the environmental impact, or a symbolic representation, for example to highlight the
integration and the interference among parts and
objects. Because the virtual spaces are shared, persons from different places can meet in the virtual
prototype to examine a design, to discuss problems
and to take decisions. Decisions made in early design
phases cost less than those made later, since changes
requested during the construction process, if they are
not impossible, will result in increased costs.
Design stages, as soon as they are computer modelled, are made available across the net. It could be
possible to have no intrinsic gap between conception,
simulation, examination and decision. Moreover, due
to SVR the decision making process can involve
every participant, no matter what time-schedule-appointment. Everyone, in front of herrhis workstation, laptop or notebook, can examine the shared
virtual prototype and join a meeting Fig. 4 . Ž .
Porta Susa is a large-scale project involving several teams working on different aspects, sometimes
Fig. 4. On-line meeting in the virtual auditorium.
224 L. CaneparorAutomation in Construction 10 2001 217–228 ( )
distinct, but more often interrelated. Sharing 3D data
among the teams is necessary but not sufficient,
because it is essential to make and keep these data
coherent. The coherence is based on both modularity
and extensibility. VRML standard has been conceived with modularity and extensibility in mind.
VRML is structured in blocks, defined as nodes in
the VRML syntax. The nodes can be loaded separately and then easily grouped. Each node can be
upgraded or substituted and new nodes can be added.
In the Porta Susa system a taxonomy of VRML
nodes has been defined, of which the most primitive
elements are the building objects. These objects are
available on the server, and shared among the various participants. The nodes-objects can be easily
combined into more complex one, as far as whole
buildings.
4.2. Three-dimensional data management
It has been previously mentioned that we expect
the VR to be a paradigm shift. VR on the Internet
consists of a new way of interacting not only with
representations, but also with construction information 14 . Spatial representation is crucial for explor- w x
ing architecture and buildings, but SVR should not
be limited to this task.
SVR worlds can be modelled to represent not
only construction objects, but also the interrelation
between the construction objects and the information
generated during the project.
The Porta Susa project consists of thousands of
drawings, drafts, blueprints, pages of reports and
technical specifications, data, historical changes, etc.
A primary aim of an information system on the
project is storing and retrieving such a vast amount
of heterogeneous documents, which varies and modifies during the life of the project itself. SVR offers
the information system two paradigms: the construction model and the document model. The two models
are presented separately, but in fact they are closely
interrelated, because SVR allows users to move from
one model to the other and back again.
4.2.1. Construction model
The construction model is a simplified three-dimensional SVR model of the overall Porta Susa area.
To store a document whatever its medium , the Ž .
user ‘‘walks’’ into the model up to the objectrbuilding which that document relates to. Then she or he
just links the document to the related object or group
of objects. The links between a document and objectrs are structured in:
fl Position: associates the document to the pertinent
construction objectrs;
fl Classification: is a, defines a taxonomy between –
a document and objectrs;
fl Decomposition: part of, structures the relation- –
ships between a document and objectrs that are
made up of items or components.
Moreover, each document has a set of attributes:
author, date, version and type. The predefined values
of document type are: drawing, text, image, model,
plot sheet, report, video, spreadsheet. To retrieve a
document, the users explore the VR model up to the
object to which the document relates and then with
the cursor srhe explores the surroundings by selecting URLs hyper-links to the documents. The VRML
and Java permit the building of a ‘‘web’’ of links
between the 3D models of the construction objects
and the documents across the Internet, allowing users
to view different and remote servers as ubiquitous
data sources. The various media are managed transparently by the MIME protocol, freeing the user
from most concerns about data formats and their
compatibility.
4.2.2. Classification and decomposition model
The Classification and Decomposition model represents the relationships between documents and
construction objects. The structure of the relationships between documents and objects is more easily
understood as a graph Fig. 5 . The documents and Ž .
construction objects are the nodes, while is a – and
part of – relationships are the arrows, respectively
black and white, connecting them.
To get to a document or construction item it is
possible to move up or down the classification following the arrows. Clicking on a node retrieves and
opens the associated document.
4.2.3. Document model
The document model presents the links connecting documents, directories and servers. The single
documents are the nodes and the hyper-links are the
L. CaneparorAutomation in Construction 10 2001 217–228 ( ) 225
Fig. 5. The documents and construction objects are represented as the nodes, while classification and decomposition relationships are the
arrows connecting them.
arrows connecting them. Further objects represented
are the directories, grouping document-nodes, and
the servers, storing the directories. The graphical
representation, whether two or three-dimensional
Ž . Fig. 6 , highlights the organisational structure of the
project, and makes evident the relations between the
documents accessible through the net. The user can
explore the overall documentation of the project
‘‘flying through’’ the model of the relations between
the documents, and can browse the interrelated documents by clicking on.
4.3. Virtual site
The virtual site is the virtual environment where
people involved in the project connect and ‘‘walk’’
through the retrieve information or find a resource,
to meet a colleague, to discuss a topic and to take a
Fig. 6. 2D and 3D navigable maps of the hyper-links between documents in the Porta Susa project.
226 L. CaneparorAutomation in Construction 10 2001 217–228 ( )
decision regarding an aspect of the project. The
virtual site is not the model of a real, physical, place,
but a representation of construction resources, objects and processes.
4.3.1. Stands
The participating contractors, subcontractors,
firms, suppliers and other trading partners manage
their own virtual stands in the area of the project on
which they are working. These stands represent the
distribution of know-how, duties, responsibilities and
jobs and provide hyper-links to relevant information
and to the people who are working on it. The cluster
of these stands constitutes the centre of the Virtual
Site. Around this centre there is an auditorium, where
participants in the project can meet each other and
discuss by means of the SVR tools cf. Section 3.5 Ž .
Ž . Fig. 4 . There is also a library into which one can
enter to gain access to the 3D construction and
documents models cf. Section 4.2 . Ž .
4.3.2. Resources
The resources of the project are explicitly represented by 3D icons, e.g., people or machines. Clicking on the icon is retrieved and displayed the record
of the resource. For people is specified knowledge,
experience, task currently carried and contact info.
For machines is specified the technical details, owner
or responsible, schedule, etc.
In the Virtual Site of the Porta Susa project were
not defined explicit workflow tools to assign tasks to
resources or the procedures they have to go through.
4.4. Broadcast
The SVR field of experience across the Internet
can establish contacts between public administrators
and citizens. Citizens are identified as users of services, public and private transport or spaces, that is,
people with demands and aspirations for the Porta
Susa urban project. For planners, architects and public decision-makers SVR offers a new way of communicating their ideas. It enables them to broadcast
a project or a plan.
SVR demonstrated communicative capabilities to
renew interest in ‘‘dated’’ media. In collaboration
with the Italian national television company RAI , Ž .
multimedia events were created, where both TV
and SVR interacted successfully. 8 SVR technology
proved reliable in supporting thousands of concurrent users.
The TV broadcast gained interactivity from computers and networks: people were able to visit the
Porta Susa project from their homes or offices, and
once inside it could communicate with the public
decision-makers in the television studio. Meanwhile,
SVR through television was able to reach groups
with disparate interests, as well people not involved
in the digital wave.
5. The case
SVR system was extensively used during the last
year of the Spina project. It spanned the overall
organisation: from the technical offices to the site
staff. The main contractors in the project were four
with about 100 subcontractors. The technical and
administrative staff involved was 150, while the site
workers about 350.
As previously mentioned, 1200 registered letters
were exchanged each year. Reports and technical
specifications summed to over 10,000 pages, while
the drafts and blueprints were 3500.
The personal computers used were about 200:
50% in the technical departments-firms, 30% in the
administrative and managing offices and 20% on-site.
Turin’s wide fibre-optic Intranet 6 assured from 2 w x
to 20 Mbitrs access to the computers in the
metropolitan area, while for outside access the Intranet had ATM links to major commercial and
academic Internet nodes. The SVR main server was
a SUN workstation with ATM access to the Intranet.
Interviews to users reported that 68% considered
SVR as useful. The satisfaction raised to 76% among
the technical and administrative staff, which previously had some kind of experience with PDM or
databases.
The users pointed out that the effectiveness of
SVR decreased during the project life. This negative
effect was foreseen during the system analysis primarily due to the scale of the project: as the number
8
The videotape can be requested from the author.
L. CaneparorAutomation in Construction 10 2001 217–228 ( ) 227
of data referenced in the SVR models increased,
limitations emerged from the manual cataloguing of
the documents and the size of SVR models.
5.1. Manual cataloguing
The SVR system had to manage with the commonly used software packages in 1996–1997. Most
of the CAD systems used at that time were geometric-drawing oriented. So, despite the object oriented
nature of VRML, explicit relationships between a
document e.g., a drawing and a construction object Ž .
in the SVR model had to be defined by the user. A
human, whatever her or his skills and knowledge,
can consider only a part fraction of these relationships cf. Section 4.2 . Moreover in certain cases, the Ž .
potentialities of the three-dimensional data management were reduced by the user’s incomplete definition of the relationships or their misinterpretation,
whether due to poor comprehension of the information paradigm or the structure of the specific construction object.
5.2. Size of SVR models
As the scale of a project and the number of
documents increased, the level of the detail of a SVR
model had to grow to support the unique definition
of relationships between documents and construction
objects. In the Porta Susa implementation an upper
limit to the complexity of the SVR models was fixed
by the hardware and software available at the time:
only the 35% of the PCs had state of the art CPUs
and more than 32 Mb of RAM. Moreover, in 1996–
Ž1997 3D graphics accelerator cards e.g., OpenGL,.
DirectX were expensive and for this reason limited
to tech. departments.
These practical constraints fixed the limit of the
number of polygons suitable for a SVR model. While
modularity, Inline nodes of VRML, proved frustrating because required too frequent regeneration and
loading of the models.
6. Conclusion and present work
The Porta Susa project demonstrates that SVR can
deliver a paradigm shift in data representation and
management, from 2D graphics to 3D models, from
window based interaction to space exploration.
Shared virtual environments have proved a powerful tool for collaborative design, to examine and
discuss designs and technological solutions, and for
the management of construction information. SVR
demonstrates an outstanding possibility to access a
large amount of design and project multimedia documentation, which is intrinsically related to a spatial
paradigm.
There was no direct evaluation of the impact of
the SVR system on the competitiveness of the project. The impression is that the cost of training the
people in the use of the system roughly balances the
improvements in performance, especially in the case
of a large-scale project, where heterogeneous contractors interact often for a limited period. The training is not aimed at the SVR technology itself, which
resulted intuitive, but to the integrated use of various
software tools required by the system.
The experience evidenced the main limitations to
the SVR data management profitability derived from
the manual, time consuming and error prone, struc-
Žturing of the information relationships cf. Section.
4.2 .
Present development of the system is focused on
automatic translation of product data in a SVR model.
The acquisition of product data is based on STEP
and IFC standards. Both the standards rely on the
Express language 15 to describe the data structures w x
of the different components of a product. Express
entities, associations and attributes are parsed and
mapped to a Java 3D model 16 , where they are w x
implemented by URLs links.
Acknowledgements
Participating to the project are: Councilor for
special projects, Turin Council; State Railway;
AutoDesk Italia; Kinetix; Texas Instruments Italia.
Parts of this research have been funded by the
Consiglio Nazionale delle Ricerche, Progetto Finalizzato on Problems of complex design, co-ordinator Prof. Edoardo Benevenuto. The public side of
the Porta Susa project is accessible on-line at:
http:rrwww.comune.torino.itrspina2. Further information on the Porta Susa area is available at: http:rr
sat00103.comune.torino.itr.
228 L. CaneparorAutomation in Construction 10 2001 217–228 ( )
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