Our seas and oceans hide a plethora of archaeological sites such as ancient shipwrecks that, over time, are being destroyed through activities such as deepwater trawling and treasure hunting. In 2006, a multidisciplinary team of 11 European institutions established the Venus (Virtual Exploration of Underwater Sites) consortium to make underwater sites more accessible by generating thorough, exhaustive 3D records for virtual exploration

Bale, Kim

Chapman, Paul

Drap, Pierre

English

Glasgow School of Art: RADAR

	Published	by	the	IEEE	Computer	Society	 0272-1716/10/$26.00	©	2010	IEEE	 IEEE	Computer	Graphics	and	Applications 85Visualization Viewpoints Editor: Theresa-Marie RhyneWe	All	Live	in	a	Virtual	SubmarinePaul Chapman Glasgow School of ArtKim BaleUniversity of HullPierre Drap Laboratoire des Sciences de l’Information et des Systèmes, MarseilleOur seas and oceans hide a plethora of ar-chaeological sites such as ancient ship-wrecks that, over time, are being destroyed through activities such as deepwater trawling and treasure hunting. In 2006, a multidisciplinary team of 11 European institutions established the Venus (Virtual Exploration of Underwater Sites)1consortium to make underwater sites more acces-sible by generating thorough, exhaustive 3D re-cords for virtual exploration.Over the past three years, we surveyed several shipwrecks around Europe and investigated ad-vanced techniques for data acquisition using both autonomous and remotely operated vehicles cou-pled with innovative sonar and photogrammetric equipment. Access to most underwater sites can be diffi cult and hazardous owing to deep waters. However, this same inhospitable environment of-fers extraordinary opportunities to archaeologists because darkness, low temperatures, and low oxy-gen rates are all favorable to preservation.From a visualization pipeline perspective, this project had two main challenges. First, we had to gather large amounts of raw data from vari-ous sources. Then, we had to develop techniques to fi lter, calibrate, and map the data and then bring it all together into a single accurate visual representation.Venus	Goals	and	ObjectivesThese underwater sites are out of reach to all but a few specially trained archaeologists. Recre-ating the sites as interactive virtual environments lets both experts and the general public study these important pieces of (disappearing) cultural heritage in a safe, cost-effective, and pedagogical environment.The Venus project’s objectives included■ defi ning best practices for collecting and storing data from archaeological sites,■ surveying wrecks using remotely operated ve-hicles (ROVs), and■ developing software tools for visualizing, and immersively interacting with, the collected data.To help achieve most of these objectives, the proj-ect used contemporary computer graphics and visu-alization techniques in various forms. For example, using an ROV to accurately survey shipwrecks can be complex and diffi cult for the pilot. However, through real-time visualization and tracking tech-niques, we can provide the pilot with a real-time 3D visualization of the ROV accurately positioned in relation to a prerendered 3D bathymetric sea-bed (color coded according to depth). This visual-ization might also include the ROV’s “eyes” via a video feed from specially mounted cameras on the submersible. We can further augment the visual-ization to provide a “snail trail” over areas already photographed and scanned. This both facilitates identifi cation of areas to be surveyed and identi-fi es a possible exit route in case the ROV umbilical becomes snagged.The project’s end users are archaeologists and the general public. Here, we focus on visualization for (and dissemination to) the general public. Ar-chaeologists aren’t concerned with plant life and underwater-lighting effects; they need a clear vi-sion of the whole site (sometimes without the sea-bed) and multiple interactions with the artifact. The general public, however, want to experience realistic virtual dives down to accurate visualiza-tions of archaeological sites as though they were actually piloting the submersible.PianosaPart of the project involved surveying the under-water archaeological site off the island of Pianosa, in the Tuscan archipelago. This site, discovered in 1989 by divers Giuseppe Adriani and Paolo Vac-cari, is near the Scoglio della Scola (a large rock), off the island’s east coast at a depth of 35 m. At the site are about 100 amphorae (ancient jars with two handles typically used to transport oil or wine) of different origins and epochs. Figure 1 shows a multibeam-sonar survey of the site.The Pianosa survey involved signifi cant interdis-ciplinary collaboration and focused on collecting georeferenced optical data for photogrammetric reconstruction. The Venus team determined an 86	 January/February	2010Visualization	Viewpointsarea to be surveyed around the site and prepared it with 2-m scale bars and 15 cement block mark-ers to define a control point calibration network for the ROV to measure. The data was collected by divers from the French National Centre for Scien-tific Research, a Venus partner, and by Integrated Systems for Marine Environment, which provided a Phantom S2 ROV for georeferencing the photo-grammetric data.Data	AcquisitionWe generated the photogrammetric survey using hundreds of overlapping photographs. We mea-sured homologous points on the photographs to orient all the photographs into a local reference system. We then used the cement block positions provided by the ROV navigation data that were consistent with bathymetric-sonar data.Figure 2 shows how we used visualization and photogrammetric tools to help unify the data sets. In this example, we used the Arpenteur photo-grammetric and visualization toolbox2 to gener-ate and visualize a 3D model of the seabed using the corresponding overlapping and superimposed photographs. We also gathered more extensive seabed terrain data, using multibeam bathymet-ric sonar.Modeling	the	AmphoraeThe immersive visualization required 3D geomet-ric modeling of the amphorae, which was driven by expert (archaeological) knowledge. We imple-mented the modeling procedure in Java and con-nected it to Arpenteur. The procedure is revisable over time, allowing reprocessing or augmentation as new data becomes available. We stored the re-sulting models in a repository database for further research and for visualization. Figure 3 shows a range of computer-generated 3D amphorae models used in the project.The 3D Modeling ProcessThe process consisted of two steps: developing theoretical models and implementing a decision support system.The theoretical models. Amphora classification in ar-chaeology relies heavily on dimension information related to specific object features—for example, the neck. In providing a theoretical model for a specific amphora class, it makes sense to measure these features directly on actual artifacts from the site. At the Pianosa site, the divers carefully removed (and later returned) six amphorae, which we used as a paradigm to define the amphorae’s theoretical models. Because these six don’t account for all the classes of amphorae at the site, we complemented the direct observations of the finds with drawings and information from archival data. For example, we modeled type Gauloise 3 amphorae accord-ing to the typology presented by the University of York Archaeological Data Service (http://ads.ahds.ac.uk/catalogue/archive/amphora_ahrb_2005/details.cfm?id=135).In defining the theoretical model, the diver-sity of the objects handled by the archaeologists and their surfaces’ geometric complexity led us to search for stable morphological characteristics of the objects from which we could take diagnostic Figure	1.	A	multibeam-sonar	image	of	the	underwater	archaeological	site	near	the	island	of	Pianosa,	off	the	west	coast	of	Italy.	The	site	contains	approximately	100	amphorae	of	different	origins	and	epochs.Figure	2.	Oriented	photographs	visualized	in	VRML	with	the	nontextured	seabed	obtained	using	photo-grammetry.	We	used	this	unified	data	to	create	our	3D	virtual	environment.	 IEEE	Computer	Graphics	and	Applications	 87measurements. To approximate these characteris-tics, we used a series of simple geometric primi-tives, which served as an interface between the photogrammetric measurements and the underly-ing model. For amphorae, we defined four mea-surement areas: rim, handle, belly, and base (see Figure 4). Using the least-square method, we fit a set of simple geometric primitives onto the mea-sured points—for instance, a circle on the rim or belly points, or a line on the base point.The decision support system. Photogrammetric mea-surements are highly incomplete (an object might be partially occluded or might have deteriorated). So, we used the Jess rule-based expert system (http://herzberg.ca.sandia.gov/jess) to determine the best strategy for providing the studied object’s geometric parameters. The system started from the measurement process and handled the default data as defined in the theoretical models.The expert system only performs geometric computation and is hidden behind the Arpenteur user interface. It’s extremely useful to archaeolo-gists because it helps fill the missing amphorae information with theoretical data. The resulting object is therefore based on a theoretical model, dimensioned by photogrammetric measurements.Working with the ModelsWith the Arpenteur interface, the user (generally an archaeologist) can ■ recognize the amphora type in the photographs, ■ choose the amphora type (see Figure 3) in the interface combo box, ■ measure a set of points in the zone where mea-surements are allowed (see Figure 4), ■ add archaeological comments and observations, ■ check consistency between observations and the theoretical model, and ■ store a new instance in the database.Afterward, the user can import the amphorae da-tabase into our virtual 3D environment, which we describe later.The Models’ UsefulnessAccurate recording, modeling, and visualization of the individual amphorae provides the viewer with a first-class accurate digital reconstruction of the vessel’s cargo as recorded at the time of survey. Our visualization tools have proven important for a number of tasks, such as identifying anomalies in the data. For example, because we could obtain details on demand and drill down to individual amphora data items, we could identify that one site surprisingly contained amphorae from very differ-ent epochs. Archaeologists could visualize various clusters of amphorae (in overview and zoomed-in formats) on the basis of parameters such as loca-tion, age, type, and state. So, they identified the Pianosa site as either a historical dumping ground for amphorae or a site where multiple vessels had Figure	3.	A	3D	representation	of	amphorae	models	used	in	the	Venus	project.	The	modeling	process	consisted	of	creating	theoretical	models	and	then	implementing	a	decision	support	system	that	provides	geometric	parameters	for	the	amphorae	being	studied.zxyoFigure	4.	Potential	photo	grammetric-measurement	locations	for	generating	an	amphora	instance	in	the	database.	We	defined	four	locations:	rim,	handle,	belly,	and	base.88	 January/February	2010Visualization	Viewpointssunk (at different times), along with their cargos of amphorae.Combining	the	DataWe integrated the Pianosa terrain data from the sonar bathymetry mission, the photogrammet-ric data for texture mapping, and the amphorae model database.3 At this point, this data resides in a relational database. Employing a set of Java tools, we can use this data to wrap objects from the database into a VRML representation or Open-SceneGraph data file.This final output file contains a link to every amphora in the database via a PhP interface. This interface lets the user view, check, and modify the archaeological values relating to the amphorae. Of course, the user can still access all the raw data such as measuring points, photos, and photo ori-entation used to measure an artifact.The precision for all the photographs was ap-proximately 2 cm, and the relative error was less than 5 mm when the signal was good. The abso-lute accuracy was approximately 40 cm (using the control points given by the acoustic measurement from the ROV).Visualizing	the	DataScientists have successfully been using computer graphics for a number of years to improve our un-derstanding of both offshore marine activities and land-based archaeological sites.4 However, the oil and gas industries have traditionally dominated marine visualization, focusing on activities such as pipeline operations and debris cleanup.5 Only limited research has dealt with underwater ar-chaeological visualization.We developed Venus-PD, our immersive public demonstrator, to bring interactive marine visu-alization to underwater archaeology and visual-ize data collected from Pianosa and other sites to generate an accurate first-person perspective of the entire dive process. Throughout the dive ex-perience, the user maintains full control over the virtual submarine and can manipulate it with a full six degrees of freedom, using a commercially available game controller such as the XBox 360 wireless gamepad. Figure 5 shows an archaeolo-gist launching the virtual submersible before div-ing to the Pianosa site. At the touch of a button, the user can switch to the first-person perspec-tive and experience the dive from the cockpit (see Figure 6).Venus-PD includes a storyboard feature triggered by certain events during the dive. For example, when the user finally arrives at the Pianosa site, the screen presents the wreck’s history, including a photograph of a replica of the original trading ves-sel (see Figure 7). This feature has been useful for explaining to the general public the site’s impor-tant elements and the Venus project’s significance.We developed Venus-PD using OpenScene-Graph, an open source, high-performance 3D graphics toolkit. Significant advances in graphics card technology have permitted real-time, per-pixel rendering of the underwater site, includingFigure	5.	An	archaeologist	launches	the	virtual	submarine	to	explore	deepwater	archaeological	sites.	After	launching	the	submarine,	the	user	can	switch	to	a	first-person	perspective	(see	Figure	6).Figure	6.	Venus-PD	(Virtual	Exploration	of	Underwater	Sites-Public	Demonstrator)	lets	the	user	pilot	a	virtual	submersible	down	to	accurate	digital	models	of	archaeological	sites.	This	is	a	visualization	of	the	Pianosa	site.	The	shipwreck	(see	the	inset)	no	longer	exists;	we	modeled	it	using	the	recreated	ship	in	Figure	7.	 IEEE	Computer	Graphics	and	Applications	 89 ■ realistic ocean surface rendering; ■ depth of field and fogging (used for increased depth perception); ■ silt effects; ■ lighting effects (replicating the absorption and scattering of light rays as they travel through the water column onto the seabed); and ■ underwater biological life, including fish and plants.These special effects increase the pilot’s sense of immersion and the virtual Pianosa site’s authentic-ity. Consequently, when the user locates the Pia-nosa amphorae, he or she experiences an extremely accurate representation of the archaeological site as surveyed by the Venus team over the last three years. If the real site is ever destroyed, it’s comfort-ing to know that the 3D digital copy will continue to educate and captivate the general public.The Venus project ended in July 2009; it resulted in a series of best practices and procedures for collecting, storing, and visualizing underwater archaeological data. Interestingly, various visual-ization tools developed during the project proved more successful with the general public than with the archaeologists. However, younger archaeologists (for example, PhD students) expressed real enthusi-asm for these tools. A comparative study based on a questionnaire shown to 24 underwater archaeolo-gists, along with more information and free soft-ware, is available at www.venus-project.eu. AcknowledgmentsVenus was partially supported by the European Community under project Venus (Contract IST-034924) of the Information Society Technologies Programme of the 6th Framework Programme for Research, Technology Development, and Demon-stration. The authors are solely responsible for this article’s content. It doesn’t represent the opinion of the European Community, and the European Com-munity isn’t responsible for any use that might be made of data appearing therein. We acknowledge the work and contributions of all 11 Venus partners. We also acknowledge Epoch (European Network of Excellence in Open Cultural Heritage) for support-ing the initial networking of the project members.References 1. P. Chapman et al., “Venus, Virtual ExploratioN of Un derwater Sites,” Proc. 7th VAST Int’l Symp. Virtual Reality, Archaeology, and Cultural Heritage, 2006, pp. 86–93. 2. Pierre Drap et al., “Underwater Cartography for Archaeology in the Venus Project,” Geomatica: The J. of Geospatial Information Science, Technology, and Practice, vol. 62, no. 4, 2008, pp. 419–428. 3. P. Drap, J. Seinturier, and L. Long, “A Photogrammetric Process Driven by an Expert System: A New Approach for Underwater Archaeological Surveying Applied to the ‘Grand Ribaud F’ Etruscan Wreck,” Proc. 2003 Conf. Computer Vision and Pattern Recognition Workshop, vol. 1, IEEE CS Press, 2003, p. 16. 4. E. Vote et al., “Discovering Petra: Archaeological Analysis in VR,” IEEE Computer Graphics and Applications, vol. 22, no. 5, 2002, pp. 38–50. 5. P. Chapman et al., “Real-Time Visualization in the Offshore Industry,” IEEE Computer Graphics and Applications, vol. 21, no. 4, 2001, pp. 6–10.Paul Chapman is the deputy director of the Glasgow School of Art’s Digital Design Studio. Contact him at paul@pixelbeans.net.Kim Bale is a research assistant in the University of Hull’s Department of Computer Science. Contact him at k.bale@hull.ac.uk.Pierre Drap is a researcher at the Laboratoire des Sciences de l’Information et des Systèmes, in Mar-seille, France. Contact him at pierre.drap@lsis.org.Contact department editor Theresa-Marie Rhyne at theresamarierhyne@gmail.com.Selected CS articles and columns are also available for free at http://ComputingNow.computer.org.Figure	7.	A	recreated	vessel	similar	to	the	Pianosa	wreck.	This	vessel	formed	the	basis	for	the	shipwreck	depicted	in		the	inset	in	Figure	6.For access to more content from the IEEE Computer Society, see computingnow.computer.org.This article was featured inTop articles, podcasts, and more.computingnow.computer.org

We All Live in a Virtual Submarine

	Published	by	the	IEEE	Computer	Society	 0272-1716/10/$26.00	©	2010	IEEE	 IEEE	Computer	Graphics	and	Applications 85
Visualization Viewpoints Editor: Theresa-Marie Rhyne
We	All	Live	in	a	Virtual	Submarine
Paul 
Chapman 
Glasgow 
School of Art
Kim Bale
University of 
Hull
Pierre Drap 
Laboratoire 
des Sciences de 
l’Information 
et des 
Systèmes, 
Marseille
Our seas and oceans hide a plethora of ar-chaeological sites such as ancient ship-wrecks that, over time, are being destroyed 
through activities such as deepwater trawling and 
treasure hunting. In 2006, a multidisciplinary 
team of 11 European institutions established the 
Venus (Virtual Exploration of Underwater Sites)1
consortium to make underwater sites more acces-
sible by generating thorough, exhaustive 3D re-
cords for virtual exploration.
Over the past three years, we surveyed several 
shipwrecks around Europe and investigated ad-
vanced techniques for data acquisition using both 
autonomous and remotely operated vehicles cou-
pled with innovative sonar and photogrammetric 
equipment. Access to most underwater sites can 
be diffi cult and hazardous owing to deep waters. 
However, this same inhospitable environment of-
fers extraordinary opportunities to archaeologists 
because darkness, low temperatures, and low oxy-
gen rates are all favorable to preservation.
From a visualization pipeline perspective, this 
project had two main challenges. First, we had 
to gather large amounts of raw data from vari-
ous sources. Then, we had to develop techniques 
to fi lter, calibrate, and map the data and then 
bring it all together into a single accurate visual 
representation.
Venus	Goals	and	Objectives
These underwater sites are out of reach to all 
but a few specially trained archaeologists. Recre-
ating the sites as interactive virtual environments 
lets both experts and the general public study 
these important pieces of (disappearing) cultural 
heritage in a safe, cost-effective, and pedagogical 
environment.
The Venus project’s objectives included
■ defi ning best practices for collecting and storing 
data from archaeological sites,
■ surveying wrecks using remotely operated ve-
hicles (ROVs), and
■ developing software tools for visualizing, and 
immersively interacting with, the collected data.
To help achieve most of these objectives, the proj-
ect used contemporary computer graphics and visu-
alization techniques in various forms. For example, 
using an ROV to accurately survey shipwrecks can 
be complex and diffi cult for the pilot. However, 
through real-time visualization and tracking tech-
niques, we can provide the pilot with a real-time 
3D visualization of the ROV accurately positioned 
in relation to a prerendered 3D bathymetric sea-
bed (color coded according to depth). This visual-
ization might also include the ROV’s “eyes” via a 
video feed from specially mounted cameras on the 
submersible. We can further augment the visual-
ization to provide a “snail trail” over areas already 
photographed and scanned. This both facilitates 
identifi cation of areas to be surveyed and identi-
fi es a possible exit route in case the ROV umbilical 
becomes snagged.
The project’s end users are archaeologists and 
the general public. Here, we focus on visualization 
for (and dissemination to) the general public. Ar-
chaeologists aren’t concerned with plant life and 
underwater-lighting effects; they need a clear vi-
sion of the whole site (sometimes without the sea-
bed) and multiple interactions with the artifact. 
The general public, however, want to experience 
realistic virtual dives down to accurate visualiza-
tions of archaeological sites as though they were 
actually piloting the submersible.
Pianosa
Part of the project involved surveying the under-
water archaeological site off the island of Pianosa, 
in the Tuscan archipelago. This site, discovered in 
1989 by divers Giuseppe Adriani and Paolo Vac-
cari, is near the Scoglio della Scola (a large rock), 
off the island’s east coast at a depth of 35 m. At the 
site are about 100 amphorae (ancient jars with two 
handles typically used to transport oil or wine) 
of different origins and epochs. Figure 1 shows a 
multibeam-sonar survey of the site.
The Pianosa survey involved signifi cant interdis-
ciplinary collaboration and focused on collecting 
georeferenced optical data for photogrammetric 
reconstruction. The Venus team determined an 
86	 January/February	2010
Visualization	Viewpoints
area to be surveyed around the site and prepared 
it with 2-m scale bars and 15 cement block mark-
ers to define a control point calibration network 
for the ROV to measure. The data was collected by 
divers from the French National Centre for Scien-
tific Research, a Venus partner, and by Integrated 
Systems for Marine Environment, which provided 
a Phantom S2 ROV for georeferencing the photo-
grammetric data.
Data	Acquisition
We generated the photogrammetric survey using 
hundreds of overlapping photographs. We mea-
sured homologous points on the photographs to 
orient all the photographs into a local reference 
system. We then used the cement block positions 
provided by the ROV navigation data that were 
consistent with bathymetric-sonar data.
Figure 2 shows how we used visualization and 
photogrammetric tools to help unify the data sets. 
In this example, we used the Arpenteur photo-
grammetric and visualization toolbox2 to gener-
ate and visualize a 3D model of the seabed using 
the corresponding overlapping and superimposed 
photographs. We also gathered more extensive 
seabed terrain data, using multibeam bathymet-
ric sonar.
Modeling	the	Amphorae
The immersive visualization required 3D geomet-
ric modeling of the amphorae, which was driven 
by expert (archaeological) knowledge. We imple-
mented the modeling procedure in Java and con-
nected it to Arpenteur. The procedure is revisable 
over time, allowing reprocessing or augmentation 
as new data becomes available. We stored the re-
sulting models in a repository database for further 
research and for visualization. Figure 3 shows a 
range of computer-generated 3D amphorae models 
used in the project.
The 3D Modeling Process
The process consisted of two steps: developing 
theoretical models and implementing a decision 
support system.
The theoretical models. Amphora classification in ar-
chaeology relies heavily on dimension information 
related to specific object features—for example, the 
neck. In providing a theoretical model for a specific 
amphora class, it makes sense to measure these 
features directly on actual artifacts from the site. 
At the Pianosa site, the divers carefully removed 
(and later returned) six amphorae, which we used 
as a paradigm to define the amphorae’s theoretical 
models. Because these six don’t account for all the 
classes of amphorae at the site, we complemented 
the direct observations of the finds with drawings 
and information from archival data. For example, 
we modeled type Gauloise 3 amphorae accord-
ing to the typology presented by the University of 
York Archaeological Data Service (http://ads.ahds.
ac.uk/catalogue/archive/amphora_ahrb_2005/
details.cfm?id=135).
In defining the theoretical model, the diver-
sity of the objects handled by the archaeologists 
and their surfaces’ geometric complexity led us to 
search for stable morphological characteristics of 
the objects from which we could take diagnostic 
Figure	1.	A	multibeam-sonar	image	of	the	underwater	archaeological	
site	near	the	island	of	Pianosa,	off	the	west	coast	of	Italy.	The	site	
contains	approximately	100	amphorae	of	different	origins	and	epochs.
Figure	2.	Oriented	photographs	visualized	in	VRML	
with	the	nontextured	seabed	obtained	using	photo-
grammetry.	We	used	this	unified	data	to	create	our	
3D	virtual	environment.
	 IEEE	Computer	Graphics	and	Applications	 87
measurements. To approximate these characteris-
tics, we used a series of simple geometric primi-
tives, which served as an interface between the 
photogrammetric measurements and the underly-
ing model. For amphorae, we defined four mea-
surement areas: rim, handle, belly, and base (see 
Figure 4). Using the least-square method, we fit a 
set of simple geometric primitives onto the mea-
sured points—for instance, a circle on the rim or 
belly points, or a line on the base point.
The decision support system. Photogrammetric mea-
surements are highly incomplete (an object might 
be partially occluded or might have deteriorated). 
So, we used the Jess rule-based expert system 
(http://herzberg.ca.sandia.gov/jess) to determine 
the best strategy for providing the studied object’s 
geometric parameters. The system started from 
the measurement process and handled the default 
data as defined in the theoretical models.
The expert system only performs geometric 
computation and is hidden behind the Arpenteur 
user interface. It’s extremely useful to archaeolo-
gists because it helps fill the missing amphorae 
information with theoretical data. The resulting 
object is therefore based on a theoretical model, 
dimensioned by photogrammetric measurements.
Working with the Models
With the Arpenteur interface, the user (generally 
an archaeologist) can
 ■ recognize the amphora type in the photographs,
 ■ choose the amphora type (see Figure 3) in the 
interface combo box,
 ■ measure a set of points in the zone where mea-
surements are allowed (see Figure 4),
 ■ add archaeological comments and observations,
 ■ check consistency between observations and the 
theoretical model, and
 ■ store a new instance in the database.
Afterward, the user can import the amphorae da-
tabase into our virtual 3D environment, which we 
describe later.
The Models’ Usefulness
Accurate recording, modeling, and visualization of 
the individual amphorae provides the viewer with 
a first-class accurate digital reconstruction of the 
vessel’s cargo as recorded at the time of survey. 
Our visualization tools have proven important for 
a number of tasks, such as identifying anomalies 
in the data. For example, because we could obtain 
details on demand and drill down to individual 
amphora data items, we could identify that one site 
surprisingly contained amphorae from very differ-
ent epochs. Archaeologists could visualize various 
clusters of amphorae (in overview and zoomed-in 
formats) on the basis of parameters such as loca-
tion, age, type, and state. So, they identified the 
Pianosa site as either a historical dumping ground 
for amphorae or a site where multiple vessels had 
Figure	3.	A	3D	representation	of	amphorae	models	used	in	the	Venus	project.	The	modeling	process	consisted	of	creating	
theoretical	models	and	then	implementing	a	decision	support	system	that	provides	geometric	parameters	for	the	amphorae	
being	studied.
z
x
y
o
Figure	4.	Potential	photo	grammetric-measurement	
locations	for	generating	an	amphora	instance	in	the	
database.	We	defined	four	locations:	rim,	handle,	
belly,	and	base.
88	 January/February	2010
Visualization	Viewpoints
sunk (at different times), along with their cargos 
of amphorae.
Combining	the	Data
We integrated the Pianosa terrain data from the 
sonar bathymetry mission, the photogrammet-
ric data for texture mapping, and the amphorae 
model database.3 At this point, this data resides 
in a relational database. Employing a set of Java 
tools, we can use this data to wrap objects from 
the database into a VRML representation or Open-
SceneGraph data file.
This final output file contains a link to every 
amphora in the database via a PhP interface. This 
interface lets the user view, check, and modify the 
archaeological values relating to the amphorae. Of 
course, the user can still access all the raw data 
such as measuring points, photos, and photo ori-
entation used to measure an artifact.
The precision for all the photographs was ap-
proximately 2 cm, and the relative error was less 
than 5 mm when the signal was good. The abso-
lute accuracy was approximately 40 cm (using the 
control points given by the acoustic measurement 
from the ROV).
Visualizing	the	Data
Scientists have successfully been using computer 
graphics for a number of years to improve our un-
derstanding of both offshore marine activities and 
land-based archaeological sites.4 However, the oil 
and gas industries have traditionally dominated 
marine visualization, focusing on activities such 
as pipeline operations and debris cleanup.5 Only 
limited research has dealt with underwater ar-
chaeological visualization.
We developed Venus-PD, our immersive public 
demonstrator, to bring interactive marine visu-
alization to underwater archaeology and visual-
ize data collected from Pianosa and other sites to 
generate an accurate first-person perspective of 
the entire dive process. Throughout the dive ex-
perience, the user maintains full control over the 
virtual submarine and can manipulate it with a 
full six degrees of freedom, using a commercially 
available game controller such as the XBox 360 
wireless gamepad. Figure 5 shows an archaeolo-
gist launching the virtual submersible before div-
ing to the Pianosa site. At the touch of a button, 
the user can switch to the first-person perspec-
tive and experience the dive from the cockpit (see 
Figure 6).
Venus-PD includes a storyboard feature triggered 
by certain events during the dive. For example, 
when the user finally arrives at the Pianosa site, 
the screen presents the wreck’s history, including a 
photograph of a replica of the original trading ves-
sel (see Figure 7). This feature has been useful for 
explaining to the general public the site’s impor-
tant elements and the Venus project’s significance.
We developed Venus-PD using OpenScene-
Graph, an open source, high-performance 3D 
graphics toolkit. Significant advances in graphics 
card technology have permitted real-time, per-
pixel rendering of the underwater site, including
Figure	5.	An	archaeologist	launches	the	virtual	submarine	to	explore	
deepwater	archaeological	sites.	After	launching	the	submarine,	the	user	
can	switch	to	a	first-person	perspective	(see	Figure	6).
Figure	6.	Venus-PD	(Virtual	Exploration	of	Underwater	Sites-Public	
Demonstrator)	lets	the	user	pilot	a	virtual	submersible	down	to	accurate	
digital	models	of	archaeological	sites.	This	is	a	visualization	of	the	
Pianosa	site.	The	shipwreck	(see	the	inset)	no	longer	exists;	we	modeled	
it	using	the	recreated	ship	in	Figure	7.
	 IEEE	Computer	Graphics	and	Applications	 89
 ■ realistic ocean surface rendering;
 ■ depth of field and fogging (used for increased 
depth perception);
 ■ silt effects;
 ■ lighting effects (replicating the absorption and 
scattering of light rays as they travel through the 
water column onto the seabed); and
 ■ underwater biological life, including fish and 
plants.
These special effects increase the pilot’s sense of 
immersion and the virtual Pianosa site’s authentic-
ity. Consequently, when the user locates the Pia-
nosa amphorae, he or she experiences an extremely 
accurate representation of the archaeological site 
as surveyed by the Venus team over the last three 
years. If the real site is ever destroyed, it’s comfort-
ing to know that the 3D digital copy will continue 
to educate and captivate the general public.
The Venus project ended in July 2009; it resulted in a series of best practices and procedures 
for collecting, storing, and visualizing underwater 
archaeological data. Interestingly, various visual-
ization tools developed during the project proved 
more successful with the general public than with 
the archaeologists. However, younger archaeologists 
(for example, PhD students) expressed real enthusi-
asm for these tools. A comparative study based on a 
questionnaire shown to 24 underwater archaeolo-
gists, along with more information and free soft-
ware, is available at www.venus-project.eu. 
Acknowledgments
Venus was partially supported by the European 
Community under project Venus (Contract IST-
034924) of the Information Society Technologies 
Programme of the 6th Framework Programme for 
Research, Technology Development, and Demon-
stration. The authors are solely responsible for this 
article’s content. It doesn’t represent the opinion of 
the European Community, and the European Com-
munity isn’t responsible for any use that might be 
made of data appearing therein. We acknowledge the 
work and contributions of all 11 Venus partners. 
We also acknowledge Epoch (European Network of 
Excellence in Open Cultural Heritage) for support-
ing the initial networking of the project members.
References
 1. P. Chapman et al., “Venus, Virtual ExploratioN of 
Un derwater Sites,” Proc. 7th VAST Int’l Symp. Virtual 
Reality, Archaeology, and Cultural Heritage, 2006, pp. 
86–93.
 2. Pierre Drap et al., “Underwater Cartography for 
Archaeology in the Venus Project,” Geomatica: The 
J. of Geospatial Information Science, Technology, and 
Practice, vol. 62, no. 4, 2008, pp. 419–428.
 3. P. Drap, J. Seinturier, and L. Long, “A Photogrammetric 
Process Driven by an Expert System: A New Approach 
for Underwater Archaeological Surveying Applied 
to the ‘Grand Ribaud F’ Etruscan Wreck,” Proc. 
2003 Conf. Computer Vision and Pattern Recognition 
Workshop, vol. 1, IEEE CS Press, 2003, p. 16.
 4. E. Vote et al., “Discovering Petra: Archaeological 
Analysis in VR,” IEEE Computer Graphics and 
Applications, vol. 22, no. 5, 2002, pp. 38–50.
 5. P. Chapman et al., “Real-Time Visualization in the 
Offshore Industry,” IEEE Computer Graphics and 
Applications, vol. 21, no. 4, 2001, pp. 6–10.
Paul Chapman is the deputy director of the Glasgow 
School of Art’s Digital Design Studio. Contact him 
at paul@pixelbeans.net.
Kim Bale is a research assistant in the University 
of Hull’s Department of Computer Science. Contact 
him at k.bale@hull.ac.uk.
Pierre Drap is a researcher at the Laboratoire des 
Sciences de l’Information et des Systèmes, in Mar-
seille, France. Contact him at pierre.drap@lsis.
org.
Contact department editor Theresa-Marie Rhyne at 
theresamarierhyne@gmail.com.
Selected CS articles and columns are also available 
for free at http://ComputingNow.computer.org.
Figure	7.	A	
recreated	
vessel	similar	
to	the	Pianosa	
wreck.	This	
vessel	formed	
the	basis	for	
the	shipwreck	
depicted	in		
the	inset	in	
Figure	6.
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see computingnow.computer.org.
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We All Live in a Virtual Submarine

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