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download samples collected there by previous workers alongside
their papers. This could reduce a lot of wheel reinventing!”
Not all rocks are suitable for modeling. The holes in scoriaceous
basalt are particularly difficult to handle. Even with photogenic
specimens, it may be advisable to wait for overcast conditions in
order to avoid deep shadows that will not correspond to the sun’s
direction in later viewings. If very high resolution is required, and hands via embedded fiducials.
rotation of the viewpoint is not essential, then GIGAmacro scans
may be preferable to a 3D model (Bentley, 2015). Some models
have gaps in the wireframe where they were in contact with a table
or scanner turntable. These can be covered with a plain gray
surface in MeshLab, otherwise students may be confused by the
view into the interior of the specimen. As with art and sculpture
restoration, a plain gray patch is preferable to artistic interpreta- Petchkovsky, 2012). In conclusion, it is hard to deny the fact that
tion of the missing material. If a model does not truly reflect a
verilith, that fact should be clearly stated. NextEngine distorts the
rock texture into tiger stripes at the turntable contact as seen in
the Vredefort specimen. If not cleaned up, these artifacts need to
be pointed out to students.
CONCLUSIONS
Every (physical) surfer knows that the key to success is to not be
too far ahead nor too far behind the currently breaking wave. It is
too soon to tell whether COLLADA models on Google Earth will
give way to glTF models on Cesium, or to the next unknown
wave. File formats such as .doc and .pdf persist for decades. Others
such as .wpd fade away. Currently, the most sharable 3D model
formats include .dae and .obj, but this may quickly change.
Examination of rocks in the field remains important—indeed
vital—but field geologists face many restrictions. For the author,
this has included encounters with armed security guards in Spain,
an angry muskox on Ellesmere Island, truculent farmers in
western Ireland, and liability-averse coastal homeowners in New
England. In many locations, collecting specimens may be diffi-
cult, dangerous, prohibited, or environmentally unfriendly.
Interactive virtual specimens offer a partial solution to access
issues for disabled and non-traditional students as legacy speci-
mens collected in less restrictive times can be taken out of storage
and brought back to life. After examining physical specimens in
lab class, students can be given access to 3D scans for study time.
Virtual rocks can be combined with other visualizations to fill a
gap in the size range between LiDAR outcrops and microscopic
visualizations such as virtual thin sections. The terrain repre-
sented on virtual globes is rarely resolved even to outcrop scale, so
there is a need for background auxiliary visualizations to give
hand specimens a geographical context. Common examples
include Google Street View, Photo Spheres, and GigaPans (e.g.,
Dordevic et al., 2015). Richards (2011) pioneered the concept of an
“Easter-egg-hunt.” Students are presented with digital images
such as small-scale cross-bedding samples and are challenged to
zoom in on the outcrop location from which the specimen was
collected by studying a GigaPan. Bentley (2015) used a compara-
tive GigaPan viewer to combined a GigaPan of the Massanutten
Sandstone with an instructor’s tracing of fossil tracks. Gessner et
al. (2009) studied rock fractures using digital photogrammetry,
and Sørensen et al. (2015) demonstrated that point-cloud models
of outcrops photographed at 40 m were competitive with LiDAR
scans. Outcrop-scale models can benefit from cut-aways following
the design principles in Lidal et al. (2012).
Inexpensive Virtual Reality (VR) and Augmented Reality (AR) GSA TODAY | www.geosociety.org/gsatoday
software and hardware such as FreshAiR, Poppy3D, and Google
Cardboard round off an effective, immersive, virtual field trip
experience (Cherney, 2015; Crompton and De Paor, 2015). Future
possibilities include the use of 3D printers to create tactile models
for blind students (Doyle et al., 2016). They could include audio
tracks that respond to the model’s orientation in a blind student’s
From the range of applications and future possibilities cited in
this paper, it seems likely that members of every division of GSA
could benefit from creating and sharing virtual specimens. They
can even add an element of Dionysian entertainment to our
Apollonian geoscience studies (Kingsbury and Jones, 2009;
“virtual rocks rock!”
ACKNOWLEDGMENTS
This manuscript benefitted from comments by editor Jerry Dickens,
reviewer John Geissman, and two anonymous reviewers. Melissa Beebe, Jessi
Strand, Melissa Bates, Ernestine Brown, and Nathan Rogers assisted with
scanning. This work was supported by the National Science Foundation
under grants DUE-1323419 and DUE-1540652.
SUPPLEMENTARY MATERIALS
This paper is supported by a Supplemental Data Repository
item (see footnote 1) detailing techniques for creating virtual
specimens. There are also KMZ samples that can be downloaded
and opened with the Google Earth desktop application, a sample
HTML file with an embedded interactive COLLADA model, and a
sample 3D PDF contributed by Dr. Alan Pitts.
REFERENCES CITED
123D Catch Gallery, 2016: http://123dapp.com/Gallery (last accessed
1 May 2016).
3D Warehouse, 2016: http://3dwarehouse.sketchup.com (last accessed
1 May 2016).
Agisoft, 2016, Agisoft PhotoScan: http://www.agisoft.com and http://www
.ausgeol.org/visualisations/ (last accessed 1 May 2016).
Arnaud, R., and Barnes, M.C., 2006, COLLADA: Sailing the gulf of 3D digital
content creation: Massachusetts, A.K. Peters Ltd., 237 p.
Autodesk, 2016, 123D Catch: http://www.123dapp.com/catch (last accessed
1 May 2016).
Bates, K.T., Manning, P.L., Hodgetts, D., and Sellers, W.I., 2009, Estimating
the mass properties of dinosaurs using laser imaging and 3D computer
modeling: PLoS One, v. 4, no. 2, e4532, doi: 10.1371/journal.pone.0004532.
Bemis, S.P., Micklethwaite, S., Turner, D., James, M.R., Akciz, S., Thiele, S.T.,
and Bangash, H.A., 2014, Ground-based and UAV-based photogrammetry:
A multi-scale, high-resolution mapping tool for structural geology
and paleoseismology: Journal of Structural Geology, v. 69, p. 163–178,
doi: 10.1016/j.jsg.2014.10.007.
Bennington, J.B., and Merguerian, C.M., 2003, QuickTime virtual reality
(QTVR): A wondrous tool for presenting field trips, specimens, and
microscopy in traditional and web-based instruction: http://people
.hofstra.edu/J_B_Bennington/qtvr/qtvr_object.html (last accessed
1 May 2016).
Bentley, C., 2015, Four new GIGAmacro images of sedimentary rocks: AGU
Blogosphere, http://blogs.agu.org/mountainbeltway/2015/12/23/four
-new-gigamacro-images-of-sedimentary-rocks/ (last accessed 1 May 2016).
Blenkinsop, T.G., 2012, Visualizing structural geology: From Excel to Google
Earth: Computers & Geosciences, v. 45, p. 52–56, doi: 10.1016/
j.cageo.2012.03.007.
Boggs, K.J.E, Dordevic, M.M., and Shipley, S.T., 2012, Google Earth models
with COLLADA and WxAzygy transparent interface: An example from
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