Adviser: immersive field work for planetary geoscientists

Abstract

The Adviser prototype system makes it possible for planetary geologists to conduct virtual field research on remote environments such as Antarctica and Mars. Among Adviser's interactive tools are mission-planning and measurement tools that let researchers generate new data and gain interpretive insights. Five case studies illustrate the system's applications and observed benefits

Full text

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Exploring Geovisualization
46
July/August 2006
Published by the IEEE Computer Society0272-1716/06/$20.00 © 2006 IEEE
G
eologists primarily explore the Earth
through fieldwork and by analyzing the
geological record at various points on the Earth’s sur-
face (see Figure 1a). They then integrate individual
data points about the Earth’s surface by means of more
synoptic analyses. To aid this analysis, they often use
image and topographic data that satellites acquire from
Earth’s orbit. One of the authors, who has decades of
field experience in widely varying terrain—from recent
volcanic eruptions1to the Earth’s sea floor2to Antarti-
ca’s Dry Valleys3—has demonstrated this strategy’s
value and shown how to augment it using images from
helicopters or remotely operated
vehicles.
In contrast, planetary geoscien-
tists commonly work in the reverse
order: Given the time and distances
involved, flybys and orbital space-
craft acquire the initial data from
individual moons and planets. In
some cases, more detail might come
later through lander and rover
deployments, or—in the Moon’s
case—through human explorers.
These opposite approaches result in
a huge difference in local analysis
of the Earth and other planets.
While Earth geoscientists can
employ 3D in situ strategies, most
planetary geoscientists use static or
interactive 2D visualizations for
their analyses (see Figure 1b). Although these 2D visu-
alizations are highly developed and often effective, for
tasks involving subtle 3D spatial judgments, we expect
that interactive 3D visualizations will likely lead to a
more complete understanding of the data—and in
some cases to recognition of features missed altogeth-
er in 2D visualizations.
Our goal is to enhance planetary geologists’ ability to
do field work as effectively on other planets as they can
on Earth. We also want to enhance the exploration of
remote and potentially hazardous Earth environments,
such as Antarctica. Guided by multiple questions about
Mars’s geological evolution, as well as by future mission
objectives, we’re developing the Advanced Visualiza-
tion in Solar System Exploration and Research system.4
As Figure 1c shows, Adviser lets geologists virtually enter
the field by recreating remote sites using laser altime-
try, camera, atmospheric, and other data. In develop-
ing Adviser, we face the challenges of
■ developing algorithms that interactively render a rich
3D environment that combines multiple large data
sources;
■ building tools that aid geoscientists in their research;
and
■ running formal usability studies to evaluate the sys-
tem relative to alternative approaches.
Here we describe our system and present observations
based on five case studies of its application.
System overview
Our prototype Adviser implementation operates in a
four-wall Cave using the model-view-controller design
pattern to organize data, visualizations, and interac-
tions. The Adviser system contains topography, camera
data, simulated data, and user annotation layers. We
visualize the model using OpenGL and, in particular,
the Real-Time Optimally Adaptive Meshes 2 (ROAM-2)5
to render topography and camera data interactively.
In terms of performance, an 8,192 ×8,192 heightfield
renders at 80 stereo frames per second using an Nvidia
GeForce 3000G graphics card. The heightfield can reg-
ister multiple high-resolution inset camera images,
although each inset incurs a frame-rate penalty. The
user can toggle insets on and off to find a balance
between information and frame rate. Geologists gener-
ally display three inset images, with samples ranging
from 1,000 × 1,000 to 15,000 × 14,000. The Cave pro-
The Adviser prototype system
makes it possible for planetary
geologists to conduct virtual
field research on remote
environments such as
Antarctica and Mars. Among
Adviser’s interactive tools are
mission-planning and
measurement tools that let
researchers generate new data
and gain interpretive insights.
Five case studies illustrate the
system’s applications and
observed benefits.
Andrew Forsberg, Prabhat, Graff Haley,
Andrew Bragdon, Joseph Levy, Caleb I. Fassett,
David Shean, and James W. Head III
Brown University
Sarah Milkovich
Jet Propulsion Laboratory
Mark A. Duchaineau
Lawrence Livermore National Lab
Adviser: Immersive
Field Work for
Planetary
Geoscientists
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duces an immersive effect that lets geologists feel like
they’re at the site; they achieve interaction—such as 3D
navigation and point specification—using a tracked
handheld wand-like device. They also can use a Tablet
PC for 2D line and gestural input.
Typically, geologists create a session in the laboratory,
using their target data elements, then access the session
in the Cave. They can also create new data within the
Cave and store it in a networked database that they can
subsequently access from anywhere using a Web portal.
IEEE Computer Graphics and Applications
47
1 Different types of planetary geoscience analysis. a) Glacial geologist Dave Marchant analyzes sublimation till fabrics in the Antarctic
Dry Valleys. This local data will be integrated with regional air photos and satellite images to provide a broad view of the Mars-like
Antarctic glacial processes. b) Studying 2D maps of Martian topography and camera data. c) Virtually studying topography on Mars
with Adviser.
Related Work
Many researchers are currently working on
geovisualization systems. Following are the systems
most closely related to Adviser.
Desktop systems
NASA’s World Wind system (see http://worldwind.arc.
nasa.gov) lets users interactively explore a wide variety of
terrain and image data. Google Earth (see http://earth.
google.com) lets users look at high-resolution images,
annotated data, and 3D models of some structures. The
osgPlanet viewer (see http://www.ossim.org/tiki-read_
article.php?articleId=3) can visualize large geospatial data
sets and import GIS data via the Web Mapping Server
standard (see http://portal.opengeospatial.org/files/
?artifact_id=5316).
Immersive environments
Immersive systems have been developed for a range of
specific tasks. Wright and colleagues developed a system for
creating and visualizing 3D terrain for the Mars Pathfinder
missions.1Powell and colleagues developed a data fusion
and visualization system for rover data acquired during
Mars exploration.2
Although both systems have proven useful for
investigating topographical features within a small area,
we’re interested in planetary-scale data visualization and
exploration. In that respect, research focused on exploring
large data sets 3,4is closely related to our own. While all the
immersive systems provide excellent features, Adviser
focuses on tasks and tools specific to geological exploration.
In addition to its immersive experience, Adviser offers
research-oriented tools that let geologists do fieldwork
inspired tasks.
Algorithms
Our choice of terrain-rendering algorithm was guided by
several requirements:
■ strict real-time performance for large data sets,
■ open-source code availability,
■ ease of integration with our software, and
■ utilization of the latest graphics hardware features.
While several excellent algorithms were potential
candidates for integration—including Geometry
Clipmaps,5Batched Dynamic Adaptive Meshes (BDAM),6
the Virtual Terrain Project’s Terrain Library (http://www.
vterrain.org/Doc/vtlib.html), and chunked Level-of-Detail
(LOD; http://tulrich.com/geekstuff/chunklod.html) we
chose Real-Time Optimally Adaptive Meshes 2 (ROAM-2)
because it provides interactive terrain rendering and view-
frustum culling for large data sets. While high-performance
texture and terrain-paging extensions are also available, we
have yet to integrate them into our system.
References
1. J.Wright, F. Hartman, and B. Cooper, “Immersive Environments for
Mission Operations: Beyond Mars Pathfinder,” Proc. Int’l Symp.
Space Mission Operations and Ground Data Systems (SpaceOps
98), The Space Operations Organization, 1998; http://www-
dial.jpl.nasa.gov/~john/papers/SpaceOps98/SpaceOps98.pdf.
2. M. Powell et al., “Scientific Visualization for the Mars Exploration
Rovers,” Proc. Int’l Conf. Robotics and Automation, Jet Propulsion
Laboratory, NASA, 2005; http://hdl.handle.net/2014/37614.
3. L.E. Hitchner, “The NASA Ames Virtual Planetary Exploration Test-
bed,” Proc. IEEE Wescon, vol. 36, IEEE Press, 1992, pp. 376-381.
4. D. Koller et al., “Virtual GIS: A Real-Time 3D Geographic Informa-
tion System,” Proc. IEEE Visualization Conf., IEEE CS Press, 1995,
pp. 94-100.
5. F. Losasso and H. Hoppe, “Geometry Clipmaps: Terrain Render-
ing Using Nested Regular Grids,” Proc. ACM Siggraph, ACM Press,
2004, pp. 769-776.
6. P. Cignoni et al., “BDAM—Batched Dynamic Adaptive Meshes
for High Performance Terrain Visualization,” Computer Graphics
Forum, vol. 22, no. 3, 2003, pp. 505-514.
(a) (b)(c)
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Case studies
Researchers are using Adviser to address multiple
science themes through specific applications. Case
studies 1 (general exploration) and 5 (wind visualiza-
tion) support a wide variety of tasks. In contrast, case
studies 2, 3, and 4 support graduate-level research,
and the researchers helped build them to suit their
specific needs.
While we’ve included images here to offer a general
sense of what users see, these narrow-field-of-view,
monoscopic images hardly capture the immersive expe-
rience of using Adviser in a Cave. In such an environ-
ment, the wide field of view and head-tracked stereo
viewing greatly enhance the sense of being present and,
in particular, of perceiving spatial relationships.
Case study 1: going virtually into the field
One of Adviser’s basic capabilities is that it lets users
freely explore a terrain in 3D. It is our belief that mov-
ing through a 3D environment makes it easier to under-
stand an environment’s intricacies than simply studying
a 2D map. Establishing 3D relationships among geolog-
ic units and structures is particularly important when
geologists are reconstructing the geological history of a
region or planet. In this context, vantage point is partic-
ularly important; the different perspectives obtained
when researchers constantly shift vantage points and
return to previous ones are essential. During this
process, having a continuously available field toolkit lets
researchers make and record valuable, detailed mea-
surements.
Currently, we’re using Adviser to explore 3D environ-
ments for both research and education.
Research tool.Geoscientists have used Adviser to
explore Mars and make useful observations about its
features in a context that would be difficult or impossi-
ble to achieve with a nonimmersive 2D tool. Using
Adviser as a tool to help understand the evolution of
Mars has let researchers accomplish several key tasks.
They have, for example,
■ stood inside large craters on Mars and considered illu-
mination conditions and solar insulation, and their
role in the formation and preservation of the crater’s
ice deposits;6
■ assessed the polar layered deposits’ characteristics
and distribution, which let them make thickness and
geometry measurements to understand the planet’s
recent climate history;7
■ planned and verified candidate rover traverses (or
paths) for a proposed NASA mission to explore the
North Pole’s cap;8and
■ assessed the general circulation of Martian atmos-
phere in different areas and on different time scales.
In addition, researchers previewed the Antarctic Dry
Valley field area by flying through a 3D reconstruction
of its topography with overlaid camera data. This expe-
rience helped field season candidates to train for geog-
raphy, geology, and safety in this harsh and unforgiving
region. Finally, Adviser let researchers place data col-
lected over multiple trips to the Antarctic Dry Valley
into a much broader context, using the same frame of
reference that researchers developed in the field. This
helped resolve many problems that emerged in the
field, but had proven insoluble without the context
Adviser provided.
Educational tool. Instructors have successfully
used Adviser in a range of classes, from introductory-
level courses to graduate seminars. For example, in
“Geological Sciences 5: Earth, Moon, and Mars,” more
than 100 students per year study Mars, choose an area
of it in which to pursue a specific scientific question or
investigation, and then use Adviser to visit Mars and
explore their chosen region in immersive VR. Figure 2
illustrates the difference between traditional classroom
visuals and those possible in the Adviser environment.
Students uniformly report a positive and rewarding
experience that gave them new insights into the geolo-
gy and topography of Mars and a better appreciation for
its spatial relationships.
Discussion. The large class size and time con-
straints meant that each student group had just 15 min-
utes to learn Adviser’s user interface and complete the
assignment. To minimize training time, we disabled all
Adviser tools except for navigation. This seemed reason-
able, as navigation controls appeared to be the primary
functional requirement for completing the assignment.
However, we found that the constraint led students to
Exploring Geovisualization
48
July/August 2006
2 Two tools
for teaching
geological
sciences.
Students (a) in
the classroom
and (b) in the
Cave, using
Adviser to visit
Tharsis Montes
on Mars.
(a)(b)
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describe capabilities and tools they believed would have
also been valuable. Among the students’ requests were
maps for navigation, high-resolution overlays, and addi-
tional visuals or tools for judging the size of features.
From the research and exploration-planning perspec-
tive, all participants had a uniformly positive experience
using Adviser. One said, “It’s like going to a foreign coun-
try rather than reading about it in a book!”
Case study 2: traverse planning for rover
missions
We’re currently collaborating with NASA scientists
on the Palmer Quest mission’s concept development.
Among other things, the mission plans involve landing
a rover on Mars’s North Pole and studying the polar lay-
ered deposits’ surface properties and structure. Select-
ing candidate traverses in advance is vital in mission
planning, because path constraints (slope, distance, and
so on) can be important in determining the mission’s
scope. Traverse planning is a complex activity involving
close interactions among multiple groups.
Facilitating collaboration. In our work, we tar-
geted collaboration between engineers (who are inti-
mately familiar with the rover design constraints) and
geologists (who are knowledgeable about the domain
science). These two parties’ design goals are often con-
tradictory: the rover engineers generally prefer a traverse
that navigates relatively flat terrain, whereas the geolo-
gists might prefer a traverse over steep slopes in order to
investigate deposit textures and layer outcroppings.
The Adviser system provides an integrated environ-
ment in which the two groups can collaborate effective-
ly. For example, the system lets users input roughly
sketched traverses with important waypoints. It then
overlays the traverses on the 3D topography and pre-
sents them in the context of the camera image overlays.
Engineers can choose to evaluate a target variable (such
as slope) along the traverse, and can also provide some
thresholds (such as a maximum slope of 30 degrees).
The system then computes path segments that don’t sat-
isfy the constraint and presents the information to users
in both the Cave environment (see Figure 3a) and on a
handheld Tablet PC device (see Figure 3b). Using such
a device, geologists can sketch new or modified paths
(see Figure 3c); the system then updates the traverse
and slope visualization (see Figure 3d).
Collaborators can now examine alternate routes
to bypass problematic regions. We adapted the fluid
inking system (www.cs.brown.edu/publications/
techreports/reports/CS-05-10.html) to provide a nat-
ural interface for editing 2D traverses. With it, users can
zoom into a target area on the Tablet PC and simply
sketch over problematic segments. Adviser reevaluates
the slope function on the new path accordingly and
immediately presents the results in the immersive envi-
ronment and the Tablet PC. The collaborators iterate
until a traverse that satisfies the constraints is produced;
they can then export the final traverse for more sophis-
ticated analysis.
Discussion.Presenting traverse information in 2D
with different overlays requires users to merge disparate
sources of information. The typical 3D presentation
makes the traverses easier to comprehend, but is rarely
done in a collaborative mode. Because Adviser presents
IEEE Computer Graphics and Applications
49
3 Traverse planning. (a) Initial rough triangular traverse is visualized in the Cave by a line that snaps to the terrain
and vertical bars that connect it to a graph of slope. (b) The Tablet PC’s view of the initial traverse. (c) The user
sketches a new traverse, after which (d) the system updates the traverse and slope visualization.
(a)(b)
(c) (d)
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traverses in the context of the 3D topography and
images, it noticeably enriches collaborator discussions.
In addition, geologists typically see topography with
substantial vertical exaggerations (scale factors of 15 to
30 are common). This is useful for enhancing important
topographical features characterized largely by elevation
changes, but which are diminished when visualized over
a vast area (similar to the way a nonplanar terrain appears
flat when viewed from an airplane). The rover engineers,
however, need terrain presented proportionally so they
can make accurate visual judgments. Adviser’s ability to
present the data with and without exaggeration interac-
tively enhances the analysis and mutual understanding
between the scientists and engineers.
Finally, to remove problematic traverse segments, we
decided to use 2D stroke gestures on a Tablet PC, rather
than marking a 3D path directly on the terrain. The 2D
input device seemed much simpler, because it leveraged
precise line-drawing skills and would thus avoid occlu-
sion and accuracy problems that users might encounter
by drawing 2D lines in a 3D environment. We plan to
evaluate this conjecture more formally in a user study.
Currently, Adviser computes a predetermined class of
functions, and we’re planning to incorporate function
expressions from the MathPad2system.9Associating the
3D and MathPad2variables will present a UI challenge.
Case study 3: strike and dip measurements
On Mars, the North Pole’s layered terrain is composed
of water ice and dust, and the individual layers’ thick-
ness and brightness are keys to the planet’s recent cli-
mate record. In addition, the layer spac-
ing and 3D configuration are important
for understanding their emplacement and
evolution. Do they represent a flat plane
when they’re emplaced? Or, are they
warped—either during formation (de-
posited on rough terrain) or after due
to post-emplacement deformation? The
terrain’s ice and dust layers are visualized
by combining data from two sources. The
Mars Orbiter Camera offers high-resolu-
tion images that reveal alternating dust
and ice layers, while the Mars Orbiter
Laser Altimeter topographic data lets us
calculate an individual layer’s thickness
and geometry.
Layer analysis.Recent work suggests
that these ice and dust layers encode a dis-
tinctive climate signal related to the same
orbital parameter variations—such as
periodic changes in obliquity and eccen-
tricity—that cause the Earth’s ice ages.7
To analyze the geometry of this climate
record’s individual layers, we’re using
strike and dip measurements. Field geol-
ogists use such measurements to describe
subsurface layers’ orientation and struc-
ture. The geologist typically identifies
multiple, surface-exposed points along
the same layer and then computes a best-
fit plane from the points. The intersection of this plane
with the horizontal plane forms a line; the angle
between this line and the North Pole is the strike and
the plane’s inclination is the dip. Taking multiple strike
and dip measurements along a layer can reveal whether
the layer is flat or distorted beneath the surface.
As Figures 4a and 4b show, our group’s geologists use
ArcGIS (see http://www.esri. com/software/arcgis) to
place points along a layer on a desktop system. They cal-
culate strike and dip value for a set of points. To aid point
placement, ArcGISpresents a 2D topography colormap in
conjunction with the camera image. Adviser presents the
layer data on a 3D terrain (see Figure 4c). Users can
change the gray-scale images’ contrast settings to enhance
layer details and use a wand to specify points in 3D. As
the user places more points, Adviser displays and updates
the best-fit plane, which is a rough approximation to the
local layer structure. Adviser also presents standard strike
and dip representations (glyphs and numbers), which
users can record in the virtual field notebook.
Discussion. Contrast enhancement is particularly
important for visualizing layers in the Cave as most pro-
jector output quality lags behind conventional desktop
display capabilities. We compute reasonable default val-
ues based on the mean and standard deviation of a cam-
era image’s intensity distribution, and give users
controls to selectively map the input gray-scale intensi-
ties to the entire spectrum; this effectively enhances our
current Cave projectors’ limited brightness and resolu-
tion capabilities.
Exploring Geovisualization
50
July/August 2006
4 Analyzing layered geometry using strike and dip measurements. (a) A geologist uses a
desktop ArcGIS system to take strike and dip measurements. (b) A close-up of the user-
specified points on a layer, which show the layer’s ambiguous positioning with reference
to the cliff. (c) The same area as viewed stereoscopically by the user in the Cave immedi-
ately resolves the confusion. (d) The geologist places multiple yellow points along the
exposed layer and Adviser computes a green best-fitting plane (planar to the head-
tracked user).
(a) (b)
(c)(d)
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Another key operation is layer disambiguation.
Without the topography information, a 2D layer view
can be confusing and ambiguous. Such a view also
complicates users’ ability to establish the presence of
layers relative to topographic features. Presenting lay-
ers on a 3D terrain helps disambiguate their structure
and positioning.
Finally, users have commented that layer anomalies
were easier to detect in the Cave environment, and that
Adviser helped them select sites for strike and dip mea-
surements with much greater confidence. Assuming
finite time and resources to conduct such measure-
ments, the Cave system appears to be a better environ-
ment than the 2D ArcGIS desktop for preselecting areas
with interesting layering.
In terms of future work, we want to improve how some
interactions are done in the Cave. For example, users can
place points on a layer precisely using a desktop system’s
mouse input device. However, Cave users sometimes find
placing points using the virtual laser pointer tiring and
inefficient. We’re considering whether we can improve
this technique and whether a hybrid technique—using a
laser pointer for rough positioning and a joystick for fine
positioning—would be more effective.
Case study 4: angle measurements in Antarctica
Our group’s field geologists undertake research expe-
ditions to Antarctica’s Dry Valleys. The Dry Valleys’ geo-
logical environment is a hyperarid cold polar desert; its
conditions resemble those on Mars more closely than
any other place on Earth.
Polygon analysis. In one field experiment, geolo-
gists are studying contraction-crack polygon formation
and how their structure varies along the debris-covered
glaciers.10One of their operations measures angles
between intersecting polygon margins that indicate the
presence of a crack or trough. Because mobility con-
straints limit the number of field observations possible
while in Antarctica, researchers follow field trips with
desktop-based analyses of image data, such as the Cam-
bot image in Figure 5a. As Figure 5b shows, researchers
typically use Adobe Photoshop to mark points (indicat-
ing polygons) on the high-resolution cambot images
without using topographic information. They then
compute the angle value between the polygon margins.
Multiple measurements yield statistics that can pro-
vide insight into the polygons’ spatial layout and
relationships.
The Adviser system lets geologists perform the same
measurements. Geologists can bring up high-resolution
Cambot images on the topographic base and perform
contrast enhancement to reveal the polygons (see Fig-
ure 5c) . They can then use a wand to select points on
the polygon margins (see Figure 5d), yielding an angle
value. To present overall statistics, Adviser bins the angle
values and computes a histogram, which it can option-
ally display on a Cave wall. Users can immediately
download the angle data created in the Cave in comma-
separated-value format on a standard desktop comput-
er; they can then further process the data in applications
such as MathWork’s Matlab or Microsoft Excel.
IEEE Computer Graphics and Applications
51
5 Studies of contraction-crack polygon formation in
the Mullins Valley, Antarctica. (a) Topography colormap
and Cambot image in ArcGIS. (b) In Adobe Photoshop,
researchers use blue points for angle measurement. (c)
The data set presented in the Cave and (d) examples of
groups of three user-specified yellow points that Advis-
er uses in angle measurement calculations.
(a)
(b)
(c)
(d)
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Page 7

Discussion. Using Adviser in this context offers sev-
eral benefits.
First, our field geologists find it easier to see the Cam-
bot images’ glacial lobe structures in the Cave than on
the desktop systems; they’ve noted that subtle correla-
tions between topography and camera data jump out to
the eye. For example, one user detected a new chevron-
shaped trough pattern that he hadn’t seen before.
Second, users feel an enhanced sense of presence in
the Cave environment. For example, being in the immer-
sive environment reminded one geologist of thoughts
and questions that had occurred to him during his field
season six months earlier. This is particularly significant
because he’d already been looking at the same Cambot
images on the desktop for months following the Antarc-
tica trip.
Third, the geologists said that the Dry Valleys’ light-
ing variation was fascinating when they physically vis-
ited the area, so we provided an interface that let them
interactively vary the time, day, and month to update
the solar illumination.They found this extremely useful
in understanding solar insolation’s role in polygon and
glacier development.
Finally, users reported that using Adviser helped
them find new interesting places to take angle measure-
ments. They also reported that after this experience
they would like to conduct additional measurements
with their 2D tools in those new target areas. As with
the strike and dip measurements, however, there’s no
observable advantage to placing markers on the 3D ter-
rain. In fact, using a 6 degree-of-freedom virtual laser
pointer to specify points makes the process somewhat
harder.
As for future work, our system’s current illumination
model uses an OpenGL diffuse Phong lighting model.
Computing shadows would make the scene look more
realistic and help in gauging solar effects.
Case study 5: global climate model simulations
Our group is interested in studying Mars’s Tharsis
Montes region because it contains geologically recent
tropical glaciers, emplaced when climatic conditions
were considerably different from today.11Our ability to
study and interpret this area is critical to determining
the causes of the climate changes involved in forming
tropical mountain glaciers. Key to this understanding is
the atmosphere’s behavior and general circulation
under these conditions.12By visualizing the atmos-
phere’s characteristics and evolution in the context of
the surface geology, we should be able to gain the
insights necessary to understand how these tropical
mountain glaciers are formed.
One of Adviser’s primary goals here is to provide an
integrated environment for viewing multiple scientific
data sets. Thus far, these data sets have primarily includ-
ed topographic information from Mars Orbiter Laser
Altimeter and Light Detection and Ranging (Lidar) and
image data from Mars Orbiter Camera, High Resolution
Stereo Camera(HRSC), and Cambot. We’ve begun pre-
liminary work to incorporate Forget and colleagues’
excellent General Circulation Model (GCM) simula-
tions.13The simulations provide accurate predictions of
several quantities (such as wind, solar radiation, and
surface pressure) for Mars under a range of input sce-
narios (such as dust conditions and obliquities).
Although the simulation resolution is thus far relative-
ly low (5.675 × 3.75 degree longitude-latitude grid)
compared to the other data sources, the results are state
of the art and provide valuable insight into the climatic
conditions involved in the planet’s evolution.
In our preliminary work, we’ve imported wind data
for different time steps from the Mars Climate Database
(see Figure 6a). Adviser displays the wind data at dis-
crete grid points as 3D glyphs (see Figure 6b). The sys-
tem gives users a time control to cycle through the time
steps. This has provided an initial appreciation of the
seasonal atmospheric changes’ rate and scale in this
area, and their possible role in climate evolution.12
Discussion
Among the commonalities we’ve observed in the case
studies are:
■ Using 3D topography to analyze surface features
(such as striations and troughs) in camera imagery
can be more powerful than viewing the 2D imagery
alone.
■ An immersive environment like the Cave can facili-
tate collaboration among disparate groups, especial-
ly when the goal involves a 3D spatial task.
■ Immersive exploration of planetary data can be an
effective medium for teaching students about plane-
tary geological processes.
■ Immersive visualization is a promising enhancement
to the planetary geoscientist’s conventional research
process; we’ve observed an enrichment of both the
discussion quality and the resulting insights.
We recognize the importance of conducting formal
user studies to substantiate our observations. While pur-
Exploring Geovisualization
52
July/August 2006
6 Wind data
from the Mars
Climate Data-
base. The data
as presented in
(a) 2D and (b)
in Adviser’s 3D
visualization.
(a)
(b)
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Page 8

suing such an evaluation in future works, we must over-
come unique challenges. Some research tasks require
subjects with specialized skills, such as geologists who
have significant field experience in Antarctica or who are
studying polar deposits on Mars. It might be possible to
simplify the tasks to increase our subject pool, but this
would be at the expense of the domain-specific insights
that geologists have reported from using Adviser.
Conclusion
Geologists report that Adviser is more than just an
exciting and stimulating experience: it gives them a
clearer understanding of the 3D terrains. It also helps
them
■ make better spatial judgments,
■ see details overlooked or underappreciated in 2D data
visualizations, and
■ make quantitative measurements effectively.
Further, students report a considerably enhanced learn-
ing experience from their Cave exploration expeditions.
In the future, we plan to extend Adviser to addition-
al geology research tasks on Earth and Mars in service
of the science themes. Additionally, we plan to:
■ formally evaluate the system’s mature components
■ better integrate Adviser with the geologist’s existing
working environment, and
■ support data sets on the order of terabytes.
We also plan to make Adviser’s capabilities available for
wider use in the research community.
■
Acknowledgments
We thank NASA’s Applied Information Systems
Research Program (grant no. NNG05GA61G) and Mars
Data Analysis Program (grant no. NNG04GJ99G), and
the US National Science Foundation’s Office of Polar Pro-
grams (grant no. 185850NGA) for supporting this work.
Our work was also supported in part by the Department
of Energy/Lawrence Livermore National Laboratory
research subcontract no. B527302. We thank Andries
van Dam and Sam Fulcomer for their support, and Rose-
mary Simpson for editorial feedback. Finally, we thank
the hundreds of students at Brown University who’ve
used the system and provided helpful advice.
References
1. J.W. Head and L. Wilson, “Lava Fountain Heights at Pu’u
O’o, Kilauea, Hawaii: Indicators of Amount and Variations
of Exsolved Magma Volatiles,” J. Geophys. Res., vol. 92,
1987, pp. 13715-13719.
2. J.W. Head and L. Wilson, “Deep Submarine Pyroclastic
Eruptions: Theory and Predicted Landforms and Deposits,”
J. Volcanology and Geothermal Research, vol. 121, 2003, pp.
155-193.
3. D.R. Marchant and J.W. Head, “Equilibrium Landforms in
the Dry Valleys of Antarctica: Implications for Landscape
Evolution and Climate Change on Mars,” Lunar and Plan-
etary Science 36,CD-ROM, abstract 1421, Lunar and Plan-
etary Inst., 2005.
4. J. Head et al., “Adviser: Immersive Scientific Visualization
Applied to Mars Research and Exploration,” Photogram-
metric Eng. & Remote Sensing, vol. 71, no. 10, 2005, pp.
1219-1225.
5. L.M. Hwa, M.A. Duchaineau, and K.I. Joy, “Real-Time Opti-
mal Adaptation for Planetary Geometry and Texture: 4-8
Tile Hierarchies,” IEEE Trans. Visualization and Comp.
Graphics, vol. 11, no. 4, 2005, pp. 355-368.
6. P. Russell, J.W. Head, and M.H. Hecht, “Evolution of Ice
Deposits in the Local Environment of Martian Circum-Polar
Craters and Implications for Polar Cap History,” Lunar and
Planetary Science 35, CD-ROM, abstract 2007, Lunar and
Planetary Inst., 2004.
7. S.M. Milkovich and J.W. Head, “North Polar Cap of Mars:
Polar Layered Deposit Characterization and Identification
of a Fundamental Climate Signal,” J. Geophys. Res., vol. 110,
no. E01005, 2004, doi: 10.1029/2004JE002349, pp. 1-21.
8. F.D. Carsey et al., “Palmer Quest: A Feasible Nuclear Fis-
sion ‘Vision Mission’ to the Mars Polar Caps, Lunar and
Planetary,” Lunar and Planetary Science 36, CD-ROM,
abstract 1844, Lunar and Planetary Inst., 2005.
9. J. LaViola and R. Zeleznik, “”MathPad2: A System for the
Creation and Exploration of Mathematical Sketches,” ACM
Trans. Graphics, vol. 23, no. 3, 2004, pp. 432-440.
10. J. Levy, J. Head, and D. Marchant, “The Origin and Evolution
of Oriented-Network Polygonally Patterned Ground: The
Antarctic Dry Valleys as Mars Analogue,” Lunar and Plane-
tary Science 36, CD-ROM, Lunar and Planetary Inst., 2005.
11. D.E. Shean, J.W. Head, and D.R. Marchant, “Origin and Evo-
lution of a Cold-Based Tropical Mountain Glacier on Mars:
The Pavonis Mons Fan-Shaped Deposit,” J. Geophys. Res.,
vol. 110, no. E05001, 2005, doi:10.1029/2004JE002360.
12. F. Forget et al., “Formation of Glaciers on Mars by Atmos-
pheric Precipitation at High Obliquity,” Science, vol. 311,
no. 5759, 2006, pp. 368-371.
13. F. Forget et al., “Improved General Circulation Models of
the Martian Atmosphere from the Surface to Above 80
km,” J. Geophys. Res., vol. 104, no. E10, 1999, pp. 155-176.
Andrew Forsbergis a research sci-
entist in the Brown University Graph-
ics Group. His research interests
include 2D and 3D user interfaces,
scientific visualization, and VR appli-
cations. Forsberg has a master’s
degree in computer science from
Brown University. Contact him at
asf@cs.brown.edu.
Prabhatis a staff member at Brown
University’s Center for Computation
and Visualization. His research inter-
ests include VR and scientific visual-
ization. Prabhat has a B.Tech in
computer science and engineering
from the Indian Institute of Tech-
nology, New Delhi, and an MS in com-
puter science from Brown University. Contact him at
prabhat@cs. brown.edu.
IEEE Computer Graphics and Applications
53
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Page 9

Graff Haley graduated in May
2006 with a BA in computer science
and history from Brown University.
Contact him at ghaley@cs.brown.
edu.
Andrew Bragdon is a research
assistant in the Brown University
Graphics Group. His research inter-
ests include Adviser and its associated
systems. Bragdon is an undergradu-
ate student at Brown University in
computer science and economics.
Contact him at Andrew_Bragdon@
brown.edu.
Joseph Levyis a PhD student in the
Department of Geological Sciences’
Planetary Geology group at Brown
University. His research interests
include using ice geomorphology as a
climate indicator on Earth and Mars,
particularly through comparisons
between Earth-based field data and
remotely sensed data from Mars. Contact him at
joseph_levy@brown.edu.
Caleb I. Fassettis a PhD student in
geological sciences at Brown Universi-
ty. His research interests include the
modification of the Martian surface
by water, especially early in its geolog-
ical evolution. Fassett has an ScM
from Brown University. Contact him
at Caleb_Fassett@brown.edu.
David Shean is a master’s student
in geology at Brown University. His
research interests include climate
change, glacial geomorphology, and
ice dynamics on Mars and in Antarc-
tica. Contact him at David_Shean@
brown.edu.
James W. Head III is the Scherck
Distinguished Professor of Geological
Sciences at Brown University and
chairs the geology discipline group for
the Discovery Messenger Mission to
Mercury. He is also a coinvestigator
for the European Space Agency’s Mars
Express Mission. His research inter-
ests include processes that form and modify planetary sur-
faces and interiors. Head has a PhD in geological sciences
from Brown University. Contact him at James_Head@
brown.edu.
Sarah Milkovichis a post-doctor-
al scholar at the Jet Propulsion Labo-
ratory in Pasadena, California. Her
research interests include the history
and stratigraphy of Martian polar
regions, the planet’s surface geology
with regard to recent climate history,
and the evolution of planetary sur-
faces. Milkovich has a PhD in planetary geology from
Brown University. Contact her at Sarah.M.Milkovich@
jpl.nasa.
Mark A. Duchaineauis a comput-
er scientist at Lawrence Livermore
National Laboratory’s Center for
Applied Scientific Computing. His
research interests include real-time,
multiple-resolution representations
and algorithms with applications to
large-data modeling, analysis, com-
pression, and display. Duchaineau has a PhD in comput-
er science from the University of California, Davis. Contact
him at duchaine@llnl.gov.
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