Collaboration Environments for Distributed Engineering Development of a Prototype System

Peter Törlind Mårten Stenius Mathias Johanson Peter Jeppsson Luleå University Swedish Institute of Swedish Institute for Luleå University of Technology Computer Science Information Technology of Technology SE-971 87 Luleå, Sweden Box 1263, SE-164 28 Box 1243 , SE-164 40 SE-971 87, Luleå, Sweden [email protected] Kista, Sweden Kista, Sweden [email protected] [email protected] [email protected]

Abstract The ability of high-quality audio to support socially rich In this paper a model for collaboration between engin- interaction has been demonstrated by Hindus et al. eers in a distributed virtual environment, based upon a (1996) with the Thunderwire system. The current work suite of specialised computer tools is presented. The seeks to take this further by combining high-quality au- system uses the distributed virtual reality system DIVE, dio and video over broadband networks with a shared which has been customised to allow interoperability virtual space where MCAE designs can be discussed with existing CAD systems. Other tools implemented to and exchanged. support information exchange in a product development Bowers et al. (1996) demonstrated and analysed the use project include audio-/videoconferencing software, of shared virtual environments in meeting situations. shared workspace systems for document sharing, ap- Such environments support a spatial model of interac- plication sharing tools, shared whiteboard applications tion (Benford and Fahlén 1993) which makes use of and more. The paper discusses the components of a avatars - visual representations of the participants in the prototype collaboration environment and how these environment - equipped with focus indicators and auras components together form a coherent whole from both a to enable interaction through gesture and sound. Rose- technical standpoint as well as in respect to usability is- man and Greenberg (1996) successfully used shared vir- sues. tual spaces as environments for a mixture of synchronous and asynchronous collaboration in the TeamRooms 1. INTRODUCTION system. The current work builds further on these find- This paper presents a heterogeneous environment that ings through an environment that also enables informa- marries high-quality video-conferencing, collaborative tion from external sources, such as local MCAE systems virtual environments and shared document spaces to or document repositories, to be included and also in- support distributed product development. The system creases the sense of presence during synchronous work particularly addresses the issues of orientation and user by merging collaborative virtual environments with a involvement in a shared work environment and seeks to novel videoconferencing system. provide a high sense of presence within geographically In many distributed engineering projects the tool for distributed work groups combined with a high level of sharing 3D objects has been a shared 3D-viewer or support for existing tools used in product development. shared applications. Shared applications currently have Information exchange between participants working in many limitations as far as collaboration is concerned as distributed teams is currently time consuming and cum- they are generally designed for displaying static objects bersome. There is therefore a need for methods and with a single common view for all participants. User in- tools to assist and simplify distributed collaboration teractivity is also limited. In the current work sharing (Krause, 1996). The study presented in this paper fo- geometric design data has been achieved by interfacing cuses on virtual environments to support integrated commercial CAD systems with a distributed VR envir- product development which encompasses not only onment. Mechanical Computer Aided Engineering (MCAE), but The following section discusses related work, whilst also related information of importance in the product section two gives an overview of the distributed envir- development process including multimedia objects such onment, discussing the separate applications and integ- as documents, audio and video. Currently, teams in- ration issues, and finally a test case is described. volved in product development projects must exchange information using regular mail, through face to face 2. RELATED WORK meetings involving travelling large distances and even The rapid evolution of information technology has led sending mechanical parts between different locations in to new possibilities for communication between people order to make comparisons and adjustments. and has been central to the success of many organisations. Key aspects of this development are increased ac- cessibility to global computer networks, increased com- rendering), whereas a virtual object is one that is artifi- munication bandwidth and the availability of low cially generated by a computer (e.g. a CAD model). cost/high performance computers supporting graphical Koleva and Benford (1998) gives a classification of user interfaces. Another important trend is towards in- mixed reality systems based on how information is con- creased team working through the use of technologies veyed through the boundaries (or interfaces) between such as groupware or computer-supported co-operative the real and the virtual world. work (CSCW). Ellis (1991) defines groupware as: 2.1. VR in Mechanical Engineering "computer-based systems that support groups of people engaged in a common task (or goal) and that provide an Among the “classical” applications of virtual reality interface to a shared environment.” (VR) are visualisation of different types of information and environments for simulation and training purposes Important issues of CSCW are group awareness, mul- (Bryson, 1996). ti-user interfaces, concurrency control, communication and co-ordination within the group, shared information In mechanical design, a solid model or virtual prototype space and the support of a heterogeneous, open environ- of a product and its associated data can be processed us- ment to integrate existing single-user applications. ing various software tools to analyse it’s performance or method of manufacture. Virtual reality can be used to CSCW systems are often categorised according to a complement this as a tool in collaborative work settings time/location matrix using the distinction between same to allow several people to visualise and interact with the time (synchronous) and different times (asynchronous), designed components and to simulate and verify the be- and between same place (face-to-face) and different haviour of the product (Rowell, 1997). places (distributed). The ability for virtual teams to share a single virtual Mahers and Rutherfords (1997) applied this matrix to world would make it possible for participants at differ- product development using CAD as shown in Figure 1. ent locations to work together. This would allow, for example, a team member to test the fit of the component Same Time Different Times they are working on with other parts simply by assem- bling them in a VR world instead of sending drawings, CAD with CAD files or even physical prototypes between geo- Same Single User data graphically remote sites. Place CAD management Whilst most geometric modellers use non-immersive screen graphics, semi-immersive and immersive systems using shuttered glasses, projection or head-moun- Different Collaborative Distributed ted displays (HMD) have been developed to create a Places Design CAD more believable 3D images and environments. Experi- mental immersive geometrical modellers include DIVEdit (Stenius, 1996), the 3DM system at the Uni- Figure 1 Use of CAD across time and space. versity of North Carolina (Butterworth, 1992), the ges- The system developed in the present work has been ture based MOVE ON system (Hummels et al. 1997), primary designed for collaborative design but can also and the virtual clay modelling system developed at the support different types of synchronous/ asynchronous Fraunhofer Institute (Lüddemann, 1996). These sys- distributed engineering work. tems are not without their problems as they can currently only be used to display relatively crude geometric There are many existing research systems for asyn- models and: chronous distributed engineering such as Madefast (Cutkosky, 1996), WebProM (Krause, 1997), and the "Head Mounted Displays prevent easy access to stand- CPD system (Roy, 1997). Rodgers and Huxor (1998) ard design tools, such as paper documents, telephones, used the Internet based collaboration tool BSCW for coffee, and other people in the room." (Green, 1998). distributed engineering and showed that, whilst it was The authors suggest that in many distributed engineer- very useful for asynchronous work, additional tools to ing work settings, two major situations can be identi- support synchronous activities were also required. fied: Other systems that have concentrated on synchronous 1. the design, simulation and shaping of CAD models distributed collaboration are CAIRO (Feniosky, 1996), 2. the evaluation, discussion and comparison of the res- VPE from Fraunhofer IGD (Jasnoch and Andersson), ults of (1). and the DCEE system from the Keyworth Institute (Maxfield, 1998). In the “design” stage, sophisticated MCAE tools are needed whilst the “discussion” stage is characterised by The collaboration environment presented in this paper is meetings where models and results must be compared an example of a class of applications generally referred and reviewed. These two situations put very different to as mixed reality applications that merge real and vir- demands on the visualisation, modification, and inter- tual worlds and objects. In this context Milgram and active features of a distributed collaborative VR envir- Kishino (1994) suggests the definition of a real object as onment. an object that can be view directly or in some sampled and reproduced representation (e.g. a video capture and 3. THE DISTRIBUTED ENGINEERING COLLAB- world database through which all user and application ORATION ENVIRONMENT interactions take place. Local DIVE applications thus When trying to realise a usable CSCW environment for interact with their local world database which is main- collaboration among engineers two of the most import- tained and modified via peer to peer communication ant issues are: over the network. This technique allows a clean separation between application and network interfaces.  to allow people that are located in different geo- DIVE has developed over a number of years for devel- graphical places to work together in virtual teams oping prototype virtual environments in a wide range of and application areas such as VR theatres/CAVES using a  to co-ordinate tasks assigned to different people wide range of interfaces including HMD’s. The plat- in the virtual organisation. form has a flexible, general-purpose application pro- In order to address these challenges, and specifically gramming interface which allows the DIVE system to real time synchronous work such as distributed team be used on a wide range of platforms in different distrib- meetings, a prototype system has been developed. uted environments such as broadband networks or the Internet. It is generally recognised that that CSCW systems should combine different systems rather than building In the current application, DIVE functions as a virtual monolithic applications (Brooke 1993). The prototype meeting place, at which engineers from different sites, thus consists of three parts; a distributed VR environ- with (potentially) different systems can meet, interact ment, a conferencing environment and an interface to and view CAD models and animations. DIVE thus al- the CAD system. Parts of the environment can bee seen lows both technical and geographical distance to be in Figure 2. bridged. 3.1.1. Coupling between MCAE system and VR system To enable collaborative interaction with geometric models from the MCAE system I-DEAS, an interface allow- ing users of the virtual environment direct access to I- DEAS geometric and product data management (PDM) database was developed. The user of the virtual environment can thus access I-DEAS project data and models in much the same way as when working in the MCAE- program. The interface uses CORBA to enable communication between I-DEAS and DIVE and thus allows access to remote installations of the MCAE-program re- gardless of computer architecture and distance, see Fig- ure 3.

DIVE Orbix CAE DINGVE Plugin Corba Daemon Corba Program

Figure 2 A distributed engineering session, combining a high- DIVE I-DEAS quality videoconferencing and a shared virtual environment witch interfaces a commercial CAD system. Dive Client (NT or UNIX) I-DEAS Server (NT or UNIX) In the following sections the different software and Figure 3 Interface between MCAE system and DIVE. hardware components of the prototype system are de- When a user wishes to access a CAD model via DIVE, scribed along with how the interfaces between the VR it is “checked-out” from I-DEAS to DIVE. The ex- environment, conferencing environment and CAD sys- change of data is then performed automatically using tem have been solved. appropriate formats. If both users are using I-DEAS the transfer of the solid model is done in I-DEAS propriet- 3.1. The Distributed Interactive Virtual Environment ary format and if different CAD systems are used a The SICS Distributed Interactive Virtual Environment STEP model is transferred. It is also possible to “check- (DIVE) (Hagsand, 1996; Frécon et. al, 1998a) is an ex- in” a model to a local CAD system from DIVE. This perimental platform for the development of virtual en- approach allows geometric data to be transferred whilst vironments, user interfaces and applications based on at the same time maintaining PDM meta data as well as shared, networked, 3D synthetic environments. DIVE is configuration management data, physical properties and aimed at multi-user applications, where several parti- other design parameters. cipants, represented through avatars which reflect the The DIVE representations of the solid models, as visual- actions and movements of each user, interact over a ised in the shared space, are thus representations of the computer network such as the Internet. geometric component of a richer underlying structure DIVE uses a peer-to-peer approach with no centralised which contains detailed information about a CAD en- server. Systems communicate using reliable and non- tity. The representations can thus act as access points to reliable multicasting. A central feature in the program- underlying data, such as notifications, version numbers, ming architecture of DIVE is the shared, distributed and so on. 3.1.2. Visualisation aids in the Virtual Meeting Room desktop videoconferencing systems which are optimised Practical experience from use of the prototype system for operation in low bandwidth network environments, has shown the need for visualisation aids to enhance in- such as the Internet or via ISDN, and which do not scale teraction during project discussions within the virtual well when the available bandwidth increases due to the meeting space. This is motivated by the need to provid- fact that they use highly lossy image compression al- ing a means of adding persistent comments and tags to gorithms such as H.261, H.263 or CellB. objects as well as providing mechanisms to enable ex- 3.2.2. Quality Requirements amination of related parts in detail including establish- To remove or reduce the sense of physical separation ing dimensions and distances between objects; basic between participants in a distributed engineering meet- viewing and measurement techniques found in many ing, the quality of the audio and video used must be MCAE systems. high. Jerky, low frame-rate video and low bandwidth Annotating objects: The concept of virtual “postit-like” sound ruins the feeling of presence. Synchronisation of text notes was introduced by Frécon et. al. (1998b) as a audio and video for each source must also be considered means of annotating virtual objects in shared virtual en- since bad lip-sync has a tiring effect on the listener. vironments. This concept is extended in the present Several researchers, including Watson and Sasse (1996) work by introducing time stamps and user notes to an- and Kies et al. (1996) suggest a video frame rate of at notate parts of the CAD object representations. These least 6 frames per second (fps) to maintain the percep- annotations can then be transferred to the local CAD tion of audio-video synchronisation. Bruce (1996) sug- system and be associated to the actual CAD models for gests that a much higher frame rate of 17 fps is required reference during the asynchronous work phase. to convey facial cues, especially lip-movement. Bruce Visualising details of imported models: The environ- also highlighted the importance of a good, dynamic ment supports making selected objects transparent or view of the face of the speaker to minimise the effect of semi-transparent to gain visual access to hidden parts of noise in the audio signal, since even people with normal a structure. This facility is an extension of the subject- hearing lip read to some extent. ive views (Snowdon et. al. 1995) and object hierarchy In the prototype distributed engineering system de- tools in the DIVE visualiser. By selecting a part of an veloped, it has been found that the duration (up to sever- imported assembly the user may change the transpar- al hours) and level of interaction of meetings demand ency of that branch whilst leaving other parts of the ob- high frame rates with around 15 fps at a resolution of at ject unchanged. This allows parts of the model to re- least 384x288. main opaque, whilst surrounding surfaces are made Another factor which affects the quality of the audio in- transparent or removed, leaving only a wireframe, see teraction is delay. Studies show that audio delays great- Figure 4. er than 400 ms severely compromise the interactivity of conversation (Brady, 1971). More recently, Bruce (1996) has shown that a maximum delay of 80 ms is tol- erable which is consistent with the experiences of from the present work. The current system also provides high bandwidth by using a higher sampling frequency (16 kHz) than is customary in teleconferencing. Figure 4 By changing the subjective view of parts of an object hierarchy, items of interest can be highlighted while maintain- To avoid problems with echoes it is important to have a ing the reference to other parts of an object. sound recording system with strong directional charac- The distance measurement tool allows the user to make teristics. Whilst active echo cancellation can be used rough measurements between any two points on objects with an “open” system consisting of omnidirectional mi- in the virtual meeting room. Both material thickness crophones and a speaker system, this is computationally and point-to-point distance can be measured interact- intensive and often requires dedicated hardware support. ively in this way. Using half-duplex audio (i.e. "push-to-talk") eliminates the echo problems, but O'Connail et al. (1996) have 3.2. Audio-/Videoconferencing shown that full-duplex audio better supports highly in- One of the basic requirements of a synchronous collab- teractive conversations. The solution implemented in oration environment is the possibility to see and hear all the present system is to use headphones instead of other participants. In order to make a distributed collab- speakers which, whilst somewhat inconvenient, are oration environment a feasible alternative to face-to- quickly forgotten by the users. face meetings, high quality audio- and videoconferen- Life-like reproduction of participants in an engineering cing must be integrated into the shared virtual space. meeting is achieved by projecting the screen image to 3.2.1. Introducing Smile! reproduce participants at natural size by using a video projection system. Smile! is an integrated audio-/videoconferencing system developed to provide the high quality interaction neces- 3.2.3. Media Encoding Formats sary in a distributed engineering situation (Johanson, The video coding used for Smile! is Motion JPEG 1998). The design takes full advantage of the band- which codes each frame in a video stream independently width available in high speed network environments. as a still image using the JPEG still image compression This makes it a better alternative to conventional standard (ITU-T Recommendation T.81). Although M- JPEG only reduces spatial redundancy and thus requires quently involves groups of engineers at one or more par- more bandwidth than formats such as MPEG and H.261 ticipating companies sharing the same videoconference which also reduce inter-frame or temporal redundancy, but being represented by a single avatar in the virtual there are several reasons that make M-JPEG suitable for world. Since the video images of a group of people can- videoconferencing in a distributed engineering environ- 't be sensibly rendered on a single humanoid avatar the ment. These include: possibility to render a video image of a group of people on a “videoconference unit” (maybe something like a  Availability of affordable high performance hard- TV-set) which is incorporated in the VR world, rather ware codecs than being a separate videoconference window, is being  Low compression delays investigated.  High image quality The currently implemented solution is to give each par- ticipating avatar a different coloured shirt which corres-  Ease of exchange of video images and animations ponds to the colour of the window frame for their video from other applications (e.g. CAD-systems) images in the conference system. The use of a logotype The audio coding used in Smile! is uncompressed linear to achieve this visual association is also possible. The PCM coding with 16 bits/sample at 16 kHz. Although colouring of the avatars and the associated video win- speech can be coded very efficiently using sophisticated dows is a trivial programming task. The only issue is audio coding techniques, this was never a design goal how to find a unique identification of each participant in for Smile!. Instead the approach has been to try to keep the conferencing system as well as in the VR-system the audio as life-like as possible to enhance the feeling and to establish a correlation between the two. Since the of a shared collaboration room. By using a stereo sound videoconferencing system Smile! and the VR-system reproduction system each sound source is located in the DIVE both use the USER environment variable avail- sound stage in a positioned corresponding to the associ- able in UNIX systems this one-to-one mapping was ated video windows and hence contribute to the illusion very simple to implement. of being in a shared meeting room. To provide a visual cue as to who in the virtual world is 3.2.4. Transmission of Animations and Video Clips currently talking DIVE renders "sound waves" around When engineering teams meet to discuss product the avatars of participants who are known to be speak- designs, it is of great value to be able to view anima- ing. The trigger for this comes from Smile! which tions generated from the CAD systems. Functionality already incorporates a silence sensor (applying a has been included in the Smile! system for streaming threshold function to the input audio signal from each animations to all members of a conference. The sender participant's microphone) to avoid sending audio pack- can control playback interactively, pausing, resuming, ets to the network if a user is silent. The DIVE Com- fast forwarding and so on via a simple control panel. mand Interface (DCI) allows an external application such as Smile! to connect a socket to a DIVE process In the same way, video clips of real life performance and to send arbitrary TCL commands to DIVE. A nat- tests or other video-recorded material can be viewed by ural enhancement of this system would be to incorporate the meeting participants. more subtle visual representation such as moving lips on 3.2.5. Coupling between Videoconference and Virtual a humanoid avatar. World 3.2.6. Smile! Network Protocols Each participant in the distributed collaboration envir- The RTP/RTCP protocols (Real Time Protocol/Real onment is represented by an avatar in the virtual world Time Control Protocol) are used by Smile! to packet au- along with a simultaneous audio and/or video stream. dio and video data into UDP datagrams for transmission To create a coherent collaboration environment it is im- over IP-networks (Schulzrinne, 1996). For multipoint portant that there is an intuitive connection between operation, the datagrams are multicast to a class D IP- each participant's virtual representation (the avatar) and address. In network environments lacking multicast his/her voice (audio stream) and image (video stream). support, an RTP-reflector can be utilised. Since both The most advanced solution would be the tight integra- Smile! and DIVE use the RTP/RTCP protocols a com- tion between the video system and the virtual environ- mon reflector can be used for all communication. Fur- ment achieved by mapping the video image of each par- thermore, user presence awareness and basic session ticipant onto their corresponding avatar in real time. management information can easily be shared between Whilst offering the ultimate level of realism there are the applications by monitoring RTCP-packet streams. several practical problems in addition to the computa- tional complexity. Since an avatar is viewed from a dif- 3.3. The Virtual Workspace System ferent perspective by each participant multiple video The tools described so far are aimed at supporting syn- cameras would probably be needed at each node which chronous collaboration where engineers interact in a vir- would change their position in response to a viewing tual meeting place and exchange information in real avatar changing position! time. During the lifetime of an engineering project It can be questioned whether the best virtual representa- there is also a need for asynchronous information shar- tion of a participant in an engineering conference is an ing. CAD drawings and models, documents and multi- avatar in the shape of a person; which is the solution media objects need to be easily accessible to all mem- currently implemented. An engineering meeting fre- bers of the project. To support this interchange of persistent data, the prototype system uses a WWW-based virtual workspace system called BSCW (Bentley et. al., 1997) accessed through a standard WWW-browser. BSCW organises documents and other objects in a folder hierarchy (similar to a file system), categorised by MIME-types. The system can also be used for threaded discussions, planning meetings and invoking synchronous collaboration tools like DIVE and Smile!. When a user schedules a meeting using BSCW, e-mail invitations can be sent to all participants and responses logged. When the meeting is to take place the appropriate collaboration tools can be launched automatically. A presence awareness feature of BSCW, known as the Monitor, is used to keep users of the system informed about who else is currently logged on and active. This tool can be very useful in initiating spontaneous synchronous collaboration sessions (that is, meetings that are not planned in advance). Thus, BSCW not only supports document sharing but also serves as a "session dir- ectory" tool that supports the transition from an asynchronous collaboration situation to a synchronous ses- Figure 5 The geographical distribution of the three members sion. of the distributed work team.

4. TEST CASE 4.2. The Design Scenario The scenario picked up the project at the embodiment 4.1. Background design phase where the principle geometry of the winch An important part of this study was to demonstrate and had been defined, but some minor problems still existed. evaluate the system in a realistic environment. To do There were also some tasks that were not yet finished this a scenario was developed in which three different such as assembly issues related to the brake of the organisations, located in a different part of Sweden (see winch and final assembly of the winch in the crane. Figure 5), worked together in a virtual organisation to Some of the simulations of function and performance on design a winch for an offshore crane. the final geometry were still to be done. The network configuration for the test case connected 4.2.1. Team Responsibilities and Tasks the three sites (Luleå, Stockholm and Gothenburg) with The distributed team consisted of three people: a 40 Mbits/s backbone ATM network. An IP network with multicast support was realised on top of the ATM  An engineer in Luleå at a company that develops infrastructure. Since the case study and demonstrator brakes for winches. was performed using a dedicated network no resource  An engineer in Stockholm at the company that de- reservation issues had to be considered. In a public net- velops the offshore crane; responsible for the working environment, however, this is a critical factor packing of the winch assembly in the crane. since the performance of the synchronous collaboration tools (i.e. the audio-/videoconferencing tools and the  The team leader in Gothenburg whose job was to shared virtual environment) is dependent on the avail- co-ordinate the tasks, and manage the team. able bandwidth and transmission delays. Based upon an initial study of typical work patterns in In the tests the node hardware range from inexpensive mechanical engineering groups, a number of typical workstation such as SGI O2 up to high-end visualisation tasks undertaken during a typical meeting were identi- systems such as SGI Onyx2 with a CAVE display sys- fied. These included: tem. Different interaction techniques were also tested  Discuss simulation or test results. including a 3D-interaction device and a large-display touch screen.  Discuss an assembly sequence.  Transfer solid model data between the workgroup partners.  Interact with 3D geometry (inspect, annotate).  Checking interference between two parts in an assembly.

These tasks were executed in the prototype system and, during a number of test runs of the scenario, some initial observations could be made regarding the usefulness of Bentley. 1997 Basic Support for Co-operative Work on the the system within the target application area. World Wide Web, International Journal of Human-Com- puter Studies vol. 46 no. 6, June 1997, pp. 827-846. The study confirmed that the use of high quality video Brady. 1971. Effects of Transmission Delay on Conversation- and audio for teleconferencing made it easy to work to- al Behaviour in Echo-Free Telephone Systems, Bell Sys- gether for long times (for hours or more). tems Technical Journal, January 1971, pp 115-134. The multi-user virtual environment for sharing objects Bruce, V. 1996. The role of the face in communication: Im- was very useful (for interference checking, annotations, plications for videophone design, Interacting with Com- etc.). puters, no. 8, pp. 166-176. 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