Realistic Rendering of Augmented Reality Heritage Exhibitions CyberEmathy8/2014
-
Upload
cyberempathy-peer-reviewed-journal-of-visual-communication-studies -
Category
Documents
-
view
223 -
download
1
description
Transcript of Realistic Rendering of Augmented Reality Heritage Exhibitions CyberEmathy8/2014
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
Abstract:
The preservation of cultural heritage is a key concern for museums
and other cultural heritage institutions. Another important issue is
the limited space available to exhibit their collections to their
visitors. Although a number of experimental systems based on
advanced information and communication technologies such as
Web3D, virtual reality and augmented reality have been previously
developed they have not really managed to become popular mainly
because they were used for passive viewing and limited interaction.
This paper presents how realistic augmented reality kiosk
exhibitions of museum collections, including galleries and artefacts,
can be developed so that they can attract the visitor’s attention.
Advanced computer graphics rendering algorithms such as
interactive lighting and shading, fake, soft and hard shadows as well
as reflections are combined with a high-level augmented reality
tangible interface presented in real-time performance.
FOTIS LIAROKAPIS Director of Interactive Worlds Applied Research Group (iWARG), Faculty of Engineering and Computing at Coventry University and a research fellow at the Serious Games Institute.
FOTIS LIAROKAPIS
1. Realistic Rendering of Augmented Reality Heritage Exhibitions
Realistic Rendering of Augmented Reality Heritage Exhibitions / F.Liarokapis. CyberEmpathy: Visual Communication and New Media in Art, Science, Humanities, Design and Technology. ISSUE 8 /2014. Augmented Reality Studies. ISSN 2299-906X. Kokazone. Mode of access: Internet via World Wide Web.
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
Introduction
The majority of heritage institutions such as museums and art galleries has realised
that Information and Communication Technologies (ICTs) have the potential, if used
properly, to attract a large number of visitors and promote their exhibits in a better
way. Each institution makes different use of ICT technologies depending on its needs,
resulting in variety in the presentation and interaction styles available. For example,
most museums and art galleries have invested on touch-screen displays with simple
representations as the main presentation medium without investigating the
capabilities of more advanced ICT such as augmented reality (AR). Also, a number of
pilot projects have been developed by universities but their results were largely
disappointing [Arn00]. Part of the problem lies on the isolation or lack of
communication between heritage institutions and universities as well as on the
diversity of the technologies used.
Open standards such as XML, VRML and Web3D, as well as computer graphics
techniques seem to have clear benefits to assist archaeologists in their professional
work [Arn00], [WM*04] and attract the visitor’s attention. In particular, 3D
archaeological reconstruction techniques have demonstrated impressive results
focusing on the fine detail and high level of realism. Based on these accurate and
realistic 3D representations, a number of virtual museum exhibitions have been
developed [SL*05]. The concept of AR exhibitions has been around for a few years
now and researchers have designed a number of prototypes [BA*99], [Gat00],
[HC*01], allowing for more advanced representations (i.e. table-top AR exhibitions)
and interaction (i.e. natural techniques). An overview of the most significant work in
virtual and augmented museum exhibitions has been previously documented
[SL*05].
In addition, Huang et al (2005) developed a tangible photorealistic virtual museum
system that allows visitors to interact naturally and have an immersive experience
with museum exhibits [HCC05]. The ARCO project has developed realistic virtual
and augmented presentations of museum galleries and their exhibits through the use
of tangible AR interfaces [WM*04], [LS*04]. Another interesting approach is the
Virtual Showcase which is a projection-based AR display system [BF*01]. The Virtual
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
Showcase contains real scientific and cultural artefacts allowing their 3D graphical
augmentation. The virtual part of the showcase can react in various ways to a visitor,
which provides the possibility for intuitive interaction with the displayed content.
However, all of the above prototypes ‘suffer’ from advanced realistic rendering
techniques. Realism was achieved only through 3D reconstruction techniques
resulting in AR exhibitions that give a distant feeling to the visitors. The aim of this
work is to provide a list of advanced rendering techniques and illustrate how to
develop realistic AR kiosk exhibitions of museum collections, including galleries and
artefacts in order to attract the visitor’s attention. Based on previous prototypes
[LS*04], [Lia07], a number of realistic techniques such as generation of interactive
lighting, shading and transparency. Section 4, presents a methodology for generating
fake, hard and soft shadows whereas section 5, illustrates how to generate
environmental and planar reflections. Finally section 6, presents conclusions and
future work.
2. Requirements for AR Kiosk Exhibitions
Museums and other heritage exhibitions need to exhibit their collections with the aim
of educating and entertaining their visitors [MK*97]. However, they usually contain
large collections of artefacts and information presented in different locations
[BB*01]. One of the most challenging objectives is the preservation of our history and
culture, in respect to time and place. To achieve this, two conditions must happen:
the 3D representation must be accurate and the presentation realistic. Moreover, the
input of archaeologists and museum curators is necessary to define the AR
presentation style in terms of the user as well as the museum requirements. In
particular, they should know the attractiveness of each artefact and the usefulness of
the labels [BS95]. On the other hand, from the visitor’s perspective, they require
immediate, realistic and easy access to the AR information in real-time performance.
It is important for them to feel related with the augmented information as it is part of
the real environment. Technically speaking, the most important requirements
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
concerning the effectiveness of an AR exhibition relate to the quality of visualisation
and interaction techniques. Effective interaction techniques for indoor AR
environment have been previously presented [Lia07] and apart from them, the
success of a kiosk exhibition is highly related to the level of realism achieved.
Properties of the real world such as lighting, shading, shadows and reflections must
be therefore reflected to the AR kiosk exhibition.
3. Realistic Augmentation
Realistic augmentation is an issue of high importance for the AR interface system.
The major focus was to realistically augment 3D heritage scenes. To increase the
realism of the AR scene, artificial lighting was carefully integrated. The precise
manipulation of the light sources allowed for the generation of real-time shadows and
reflections. Other effects implemented to enhance realism, such as atmospheric
effects and transparency, were necessary for simulating reality. 3.1. Interactive
Lighting and Shading 3D modelling techniques have advanced to a great extend so
that the common illumination model can be predetermined and saved in a specific
computer graphics file format (i.e. 3ds, VRML). Thus, realism is an issue that is
highly dependent on modelling capabilities. In cases where the illumination model is
not pre-computed an approximation model can be used. The real world is comprised
of objects that have different characteristics. For example, some objects are extremely
shiny whereas others are not. To succeed in realistic AR rendering, the common
illumination model has to be controlled interactively. During recent years much
research work has been performed in this field [LDR00][DRB97]. The biggest
problem is to automatically match the virtual lighting information with the real
world. In this work, this is done based on user-input by controlling the position and
characteristics of the light(s) in the AR environment. To estimate the lighting model
OpenGL’s lighting model is addressed because it is one of the industry’s standard and
can easily produce quite impressive results. This model divides lighting into four
independent components: ambient, diffuse, specular and emissive. Light sources in
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
OpenGL have several properties including colour, position and direction. To light the
virtual scene more, multiple light sources can be added to the environment. The
equation used for the entire calculation in RGBA mode [SW*99] is presented below:
where Vc is the colour of each vertex, em is the emission of the material, αl is the
ambient light model, αm is the ambient material, αterm is the ambient term, dterm is
the diffusion term and sterm is the specular term. Shading is used for determining
the pixels’ colour based on lighting computations [Mol99]. There are three basic
types of shading including flat, smooth and phong shading [SW*99]. In flat shading
the colour of one particular vertex is duplicated across all the primitive vertices. This
method is very simple and works very fast but it does not give a smooth appearance
to curved surfaces because all pixels in the polygon as shaded the same. On the other
hand, smooth shading, also known as Gouraud shading, is one of the most popular
shading algorithms which interpolates light intensities across the face of a polygon
using values taken from its vertices [Mol99]. Gouraud shading is slower than flat
shading but it produces a smoother appearance across polygons as presented in
Figure 1.
Figure 1: Shading modes in AR (a) flat (top view) (b) smooth (bottom view)
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
Phong shading interpolates the normals across each polygon instead of interpolating
the vertex intensities as performed in smooth shading. Although phong shading
produces smoother results, it has the drawback of having greater computational cost
and usually is performed off-line [Ang03]. It is worth-mentioning that shading is
more appropriate when the virtual artefacts do not include any texturing information.
3.2. Transparency
The real world is composed of three types of objects: transparent, translucent and
opaque objects. The most popular method for adding transparency information for
translucent objects is alpha blending. Alpha blending is generated by rendering
polygons through a predefined mask whose density is proportional to the
transparency of the object. When the transparency effect is applied successfully, the
resultant colour of a pixel is a combination of the foreground and background colour.
The general equation for alpha, which has a normalized value of 0 to 1 for each colour
pixel, is illustrated below:
where α is the opacity of the surface, pAx,y is the colour of the pixel A and pBx,y is the
colour of the pixel B. Instead of using ray-tracing rendering, opacity can be used
instead [Ang03]. This method is based on the control of the alpha channel (α) of the
colour mode (RGBA). More specific, when blending is performed, the value of alpha
channel determines the value of each of the red, green and blue (RGB) components.
The amount of light that penetrates through surfaces is called opacity. When the
opacity of a surface is zero then the surface is transparent. The transparency of a
surface can be calculated by the following formula:
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
where tsurface is the transparency of the surface of the object. In AR environments,
transparency is an effect that can be applied very successfully in some types of
applications or scenarios [BNB05], [Lia07]. The 3D models used must be created in
such a way so that they contain transparent surfaces. Therefore, the rendering part,
transparent objects is achieved through the alpha blending mechanism.
Figure 2: Transparency levels in AR (a) less transparent (80% alpha blending) (b) more transparent (20% alpha blending)
Figure 2 shows the same textured object with different levels of transparency. Figure
2, (a), shows a 3D artefact with the alpha value close to unity (80% or 0.8) blending
while in Figure 2, (b) presents the same 3D artefact with alpha value close to zero
(20% or 0.2) blending. This effect is very useful when occluding virtual artefacts are
overlaid in a kiosk environment. Similarly, to commercial video games, using
transparency it is possible to make the virtual artefact that occludes the others so that
all artefacts are visible. In addition, transparency can be very successfully applied for
achieving other visualisation effects such as reflections (see section 5).
3.3. Atmospheric Effects
Special effects are an area of continuing research and development. The
entertainment industry (films and games mainly) has made many advances during
the last years. Fog is an existing 3D computer graphics effect that can be used to
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
create the illusion of partially transparent space between the camera and the 3D
object. This can be easily achieved by blending in the environment, a distance
dependent colour that is defined as fog factor f [Ang03]. Using an atmosphere
intensity attenuation function the rendered information can be simulated through a
hazy or smoky atmosphere [Bea04].The three most popular types of fog densities
are:linear, exponential and Gaussian. The equations usedfor the different variations
of the fog effect areillustrated following [SW*99]:
where z is the camera’s coordinate distance between the viewpoint and the fragment
centre and end and start are specified as the boundary limits correspondingly. Fog
can be generated by blending a RGB fog colour with one of the above blending
factors.
4. Shadow Generation
Shadows play a very important role for the generation of a realistic AR kiosk
environment. In reality, all artefacts have their shadows so virtual artefacts should
have as well. Two of the most important shadow algorithms [Mol99] can be
distinguished in two types: planar and curved surface shadows.
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
4.1. Planar and Curved Surfaces Shadows
Planar shadows are the simplest case of shadowing into planar surfaces. Hard
shadows may be generated using only point light sources but to create soft shadows
then area light sources have to be used. In the real world, shadows consist of a fully
shaded region, called the umbra and a partially shadowed area, called the penumbra
[Vin95] as illustrated in Figure 3.
Figure 3: Shadow generation
A way to simulate soft shadows is to use the shadow map algorithm. In general, soft
shadows are preferred because the soft edges make the user aware that the shadow is
indeed a shadow. On the other hand, hard- edged shadows can be confusing and give
the illusion of actual geometric features. Shadows projected on curved surfaces are
considered to be an extension of planar shadows. Finally, another popular solution is
to use a generated shadow image as a projective texture [Mol99].
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
4.2. Fake Shadows
Fake shadows are very easy to generate and even if they are blurred or inaccurate,
they can give an estimation of the depth [Mol99]. The easiest was to implement fake
shadows is to project a 3D shape, which is similar to the rendered object, on the
ground and the paint it black. In most of the applications, a simple geometrical shape
is usually enough. Although the most popular shape is the sphere, other shapes can
produce quite effective results such as the torus as illustrated in Figure 4.
Figure 4: Fake shadow generation using (a) Torus (left view) (b) Sphere (right view)
On both images of Figure 4, a virtual torus is superimposed on a marker card but
different fake shadows are projected onto the ground. The fake shadow presented in
Figure 4, (a) is represented using a torus while in Figure 4, (b) the shadow is
represented using a sphere. The difference between these two types is on the
appearance of the virtual shadow. The sphere produces much smoother results but
this is not always the case. Other geometrical shapes that have been experimentally
tested include the square, the cube, the cone, the pyramid and the teapot. Although
this type of shadows is sufficient for some applications, it cannot be used in cases
where realism is an important factor. To realize a more realistic augmentation, more
advanced shadowing techniques are required, such as planar shadows.
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
4.3. Planar Shadows
Realistic shadows are quite difficult to implement in real-time [Vin95] but planar
projection shadows can produce very nice effects without having to account for the
generation of soft shadows. Even if there are many algorithms for generating shadow
algorithms like ray- tracing, projection, shadow volumes and shadow maps [AT*01]
this work concentrates on a general solution for shadows projected onto a kiosk
presentation environment.
Figure 5: Planar shadow projection
As illustrated in Figure 5, the location of the shadow can be calculated by projecting
all the vertices of the AR object to the direction of the light source. To generate
augmented shadows an algorithm that creates a 4x4 projection matrix, Ps, in
homogeneous coordinates must be calculated based only on the plane equation
coefficients and the position of the light [Mol99]. Say that L is the position of the
point light source; P the position of a vertex of the AR artefact where the shadow is
cast; and n the normal vector of the plane (Figure 6).] below:
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
Figure 6: Calculation of the shadow projection
As a first step, a plane needs to be expressed as:
where S is the location of a point of the plane. Next the straight that passes from the
plane point in the direction of the light source is defined by the equation of a straight
line: the equation [Wat99] below:
Solving for γ and substituting into the above equations, the shadow projected point,
P’, contains the correct projection as shown below:
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
In order to turn this into a matrix, it is necessary to follow the projection matrix
convention below:
Based on the above equation, the transpose of the projection matrix that calculates
the shadow [MB99] is illustrated below:
where Lp•Pc is the dot product of plane and light position. The projection matrix has
a number of advantages compared with other methods such as fake shadows. The
most important is that it work fast and it is generic so that it can generate hard
shadows in real- time for any type of objects independently of their complexity. Two
example screenshot that illustrates a 3D representation of a simple cube (Figure 7, a)
and a tree (Figure 7, b) is shown in Figure 7.
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
Figure 7: Hard shadows (a) Canonical shape (cube, left) (b)
Non-canonical shape (tree, right) The main disadvantage of this algorithm is that it
renders the virtual information twice for each frame: once for the virtual object and
another one for its shadow. Another obvious flaw is that it can cast shadows only into
planar surfaces but with some modifications, it can be extended to be applied to
specific cases such as curved surfaces.
4.4. Fake Shadows
Although hard shadows will increase the level of realism to the AR scene, there are
still a lot of issues for achieving realistic rendering. In theory, any projection matrix
which generates hard shadows can be used for the generation of soft shadows
[Mol99]. To generate the effect of soft shadows the same principle may be applied
with some modifications. The shadow matrix needs to be calculated only once, but
the augmentation of the matrix must be performed for some 3D points that much
have a small displacement from the origin and can cover the area near the hard
shadow as illustrated in Figure 8.
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
Figure 8: Approximation of soft shadows A
Although this technique is not very computationally expensive, it does not provide
very realistic results. However, if a large number of displacements are used, then it is
possible to improve the visualisation results. To achieve more realism other
techniques, such as a frustrum-based method, need to be employed [Mol99]. 5
Reflection Generation Reflections are one of the most important ingredients for
realistic computer graphics visualisation [Mol99]. The general lighting equation also
called the rendering equation accounts for reflections and shadows [Kaj86]. The light
reflection depends on four different factors as shown from the equation [Wat99]
below:
Where LI is the light incident at a surface, LR is the reflected light, LS is the light
scattered, LA is the absorbed light and LT is the transmitted light. Reflection is a
rendering technique that generates images that look similar to ray-traced images
without having to trace the reflected rays. This implies that an instance of the real
world is painted onto a surface as it is rendered [Ang03]. In this work, two different
types of reflections have been implemented including environmental reflections and
planar reflections.
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
5.1. Environmental and Spherical Mapping
Environmental mapping, also known as reflection mapping, is a simple and effective
method of generating approximations of reflections in curved surfaces [Mol99]. It is
usually classified as category of texturing technique and can be considered as a
simplification of ray tracing [Wat99].The difference with ray-tracing is that this
mapping makes use of the direction of the reflection vector as an index pointing to an
image that contains the environment [Mol99]. An illustration of how environmental
mapping works is illustrated in Figure 9.
Figure 9: Environmental mapping
In Figure 9, the graphics camera represents the user and is defined as a vector c, the
normal of the object is defined as N and the reflection vector as r. Using these
attributes, the reflection vector of the viewer can be computer using the following
equation [Ang03], [Mol99]:
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
r = 2(N * c)N - c
where c represents the normalised vector from the graphics camera to the location of
the surface, and N is the surface normal at that location. Although, the main
limitation of environmental mapping is that the artefacts near the reflector can not be
reflected accurately it can also be used to give limited recursive reflections [MB99].
Additionally, it is possible to achieve a variation of the above method, called spherical
mapping [Ang03]. The idea is to map the environment into a sphere using
orthographic projection and then generate a texture. In this work, the image is stored
in image memory and the texture coordinates are generated automatically. The main
advantage of this technique is that it is simple to implement and provides a rough
estimation of reality. Two example screenshots illustrate how spherical mapping can
be applied on a textured 3D virtual artefact. Figure 10, (a), shows a 3D artefact with
simple texturing applied, while Figure 10, (b) illustrated the same 3D artefact with
sphere mapping.
Figure 10: Environmental mapping (a) simple texture mapping (b) sphere mapping
Another way of accurately computing the environmental map is to use standard
projections [Ang03]. In the simplest case of an AR indoor environment at least six
cameras are required to estimate six projections [Vin95]. Each projection
corresponds to each surface of the indoor environment (i.e. a kiosk environment
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
inside a museum). Using all six projections a single environmental map can be
generated. This can be then easily applied to the model as a single texture.
5.2. Planar Reflections
To realistically model reflections in AR heritage environments, many issues must be
taken into account. For example, in reality the light is scattered uniformly in all
directions depending on the material.
Figure 11: Reflection in a plane
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
In this work, the effect of mirror reflections has been implemented. Based on the
capabilities of the stencil buffer, a reflection of the object is performed onto the
virtual ground which is user-defined. The stencil buffer is initially set sixteen bits in
the pixel format function. Then, the buffer is emptied and finally the stencil test is
enabled.
Figure 12: Transparency in a user-defined plane
In Figure 12, a 3D object is overlaid on a marker card and its planar reflection is
projected on a user defined plane. Transparency is used to the virtual plane in order
to emphasise the appearance of virtual artefact. To enhance the realism of the AR
reflections, hard shadows can be projected onto the same plane.
6. Conclusions and Future Work
Realism in AR exhibitions is one of the means that museums can use to so attract the
visitor’s attention. This paper has illustrated how realistic AR kiosk exhibitions of
museum collections, including galleries and artefacts, can be developed in real-time
performance. Advanced computer graphics rendering algorithms such as interactive
lighting and shading, fake, soft and hard shadows and reflections are standard
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
features that must be included in any augmented exhibition. In the future, shadows
and reflections will be extended to operate in curved surfaces. In addition, more
advanced rendering techniques will be implemented including level-of-detail,
collision detection and ray- tracing. Finally, a lite version of the AR interface will be
ported into a handheld device such as smartphones and personal digital assistants
(PDAs) allowing for mobile AR realistic rendering inside museums.
Acknowledgments
The author would like to thank the Department of Creative Computing at Coventry University
as well as the Centre for VLSI and Computer Graphics at the University of Sussex for their
support and inspiration.
References
[Ang03] Angel, E., Interactive Computer Graphics: A Top-Down Approach Using OpenGL, Addison-
Wesley, Third Edition, 17-18, 69, 107, 322-349, 472, (2003).
[Arn00] Arnold, D.B., Computer Graphics and Archaeology: Realism and Symbiosis, In Joint ACM
SIGGRAPH and EUROGRAPHICS Campfire on Interpreting the Past in Preconference Prroceedings,
10-21, (2000).
[AT*01] Andersen, D., Thomsen, C., et al., ARS- Generator - An augmented reality shadow generator,
Report, Aalborg University, Department of Computer Science, 4th Sep-19th Dec, (2001).
[BA*99] Brogni A., Avizzano C.A., et al., Technological Approach for Cultural Heritage: Augmented
Reality, Proc. of the 8th Int’l Workshop on Robot and Human Interaction, Pisa, Italy, (1999).
[BB*01] Baber, C., Bristow, H., et al., Augmenting Museums and Art Galleries, Human-Computer
Interaction INTERACT '01, 439-447, (2001).
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
[Bea04] Beaker, H., Computer Graphics with OpenGL, Pearson Prentice Hall, Third Edition, 644,
(2004).
[BF*01] Bimber, O., Frohlich, B., Schmalsteig, D., and Encarnacao, L.M., The Virtual Showcase,
Computer Graphics and Applications, IEEE Computer Society, 21(6): 48-55, Nov/Dec, (2001).
[BNB05] Buchmann, V., Nilsen, T., and Billinghurst, M., Interaction With Partially Transparent Hands
And Objects, Proc. of the Sixth Australasian conference on User interface, ACM Press, Volume 40,
Newcastle, Australia, 17-20, (2005).
[BS95] Boisvert, D.L., and Slez, B.J., The relationship between exhibit characteristics and learning-
associated behaviours in a science museum discovery space, Science Education, 79(5), 503-518,
(1995).
[DRB97] Drettakis, G., Robert, L and Bougnoux, S., Interactive Common Illumination for Computer
Augmented Reality, Proceedings of Rendering Techniques '98 (Eighth EG Workshop Rendering), J.
Dorsey and P. Slusallek, eds., 45-56, June, (1997).
[Gat00] Gatermann, H., “From VRML to Augmented Reality Via Panorama- Integration and EAI-
Java, in Constructing the Digital Space”, Proceedings of the SiGraDi, 254-256, September (2000).
[HC*01] Hall, T., Ciolfi, L., et al., The Visitor as Virtual Archaeologist: Using Mixed Reality Technology
to Enhance Education and Social Interaction in the Museum, Proc. of Virtual Reality, Archaeology, and
Cultural Heritage, ACM Press, Glyfada, Nr Athens, November, 91-96, (2001).
[HCC05] Huang, C.R, Chen, C.S, Chung, P.C., Tangible Photorealistic Virtual Museum, Computer
Graphics and Applications, IEEE Computer Society, January/February, 25(1): 15-17, (2005).
[Kaj86] Kajiya, J.T., The rendering equation, Computer Graphics (SIGGRAPH), 20(4): 143-150,
August, (1986).
[LDR00] Loscos, C., Drettakis, G., and Robert, L., Interactive Virtual Relighting of Real Scenes,
Transactions on Visualisation and Computer Graphics, IEEE Computer Society, 6(4): 289-305,
(2000).
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
[Lia07] Liarokapis, F., An Augmented Reality Interface for Visualising and Interacting with Virtual
Content, Virtual Reality, Springer, 11(1): 23-43, (2007).
[LS*04] Liarokapis, F., Sylaiou, S., et al., An Interactive Visualisation Interface for Virtual Museums,
5th International Symposium on Virtual Reality, Archaeology and Cultural Heritage, Eurographics
Association, Brussels, Belgium, 6-10 Dec, 47-56, (2004)
[MB99] McReynolds, T., and Blythe, D., Advanced Graphics Programming Techniques Using OpenGL,
SIGGRAPH `99 Course, (1999).
[MK*97] Mase, K., Kadobayashi, R., et al., Meta-Museum: A Supportive Augmented-Reality
Environment for Knowledge Sharing, ATR Workshop on Social Agents: Humans and Machines, Kyoto,
Japan, April 21-22, (1997).
[Mol99] Moller, T., Real-Time Rendering, A K Peters Ltd, 23-38, 171, (1999).
[SL*05] Sylaiou, S., Liarokapis, F., et al., Virtual Museums: First Results of a Survey on Methods and
Tools, CIPA XX Symposium, Torino, Italy, Sept 26-1 Oct, 1138-1143, (2005).
[SW*99] Shreiner, D., Woo, M., et al., OpenGL Programming Guide: The Official Guide to Learning
OpenGL, Version 2 (5th Edition), Addison Wesley, August, (2005).
[Vin95] Vince, J., Virtual Reality Systems, Addison-Wesley Publishing Company, 180-182, 288-292,
(1995).
[Wat99] Watt, A., 3D Computer Graphics, Addision-Wesley, Third Edition, December 6, (1999).
[WM*04] White, M., Mourkoussis, N., et al., ARCO-An Architecture for Digitization, Management and
Presentation of Virtual Exhibitions, Proc. of the 22nd Int’l Conference on Computer Graphics
(CGI'2004), IEEE Computer Society, Hersonissos, Crete, June 16-19, 622-625, (2004).
CyberEmpathy – Visual and Media Studies Academic Journal
ISSUE 8/2014: Augmented Reality Studies
FOTIS LIAROKAPIS
Fotis is the director of Interactive Worlds Applied Research Group (iWARG), Faculty of Engineering
and Computing at Coventry University and a research fellow at the Serious Games Institute. He has
contributed to more than 75 refereed publications with more than 600 citations and has been invited
60 times to become member of international conference committees and has chaired 13 sessions in 8
international conferences.Fotis is the editor in chief of the International Journal of Interactive Worlds
(IJIW) and he is on the editorial advisory board of The Open Virtual Reality Journal. He has organised
VS-Games 2009 (publications chair), the STARS session of VAST 2009 (chair of state-of-the-art
reports), VS-Games 2010 (steering committee) and VS-Games 2011 (general chair). Finally, he is a
member of IEEE, IET, ACM, BCS and Eurographics.
MORE: fotisliarokapis.blogspot.com/