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ORIGINAL PAPER
An inexpensive system for continuous lake core photography
Kyle McMillan
Received: 14 December 2007 / Accepted: 8 May 2008 / Published online: 30 May 2008
� Springer Science+Business Media B.V. 2008
Abstract Representative images of split sediment
cores document geological records, serve as visual
aids for multimedia, and provide samples for image
analysis. Existing core imaging systems, often con-
taining integrated hardware and software, are capable
of providing excellent images; unfortunately these
systems are also bulky and expensive, and are
therefore limited to labs that process large volumes
of core and those actively involved in image analysis.
For most research groups such systems are unfeasible
to buy and maintain. Producing good quality core
images with a hand-held digital camera is very
difficult without a consistent lighting source, and
changes in camera angle (in all three spatial dimen-
sions) between photographs may prevent accurate
image compositing. Tripods allow for camera stabil-
ity, but typically do not accommodate downward-
facing photography. Presented here is an easily
constructed core-imaging system that minimizes
many of the drawbacks of personal digital cameras.
Software necessary for using this system is readily
available and can be run from a personal computer.
Keywords Imaging � Core � Photography
Introduction
Core images are increasingly being used, qualita-
tively and quantitatively, as records of lacustrine
paleoenvironments (e.g. Cooper 1997; Petterson et al.
1999; Saarinen and Petterson 2001; Francus et al.
2005). However, many research groups that work
with lake cores do not adequately image their cores
because they lack the necessary equipment and
expertise to do so. The system described in this
paper can be easily constructed and operated, and is
designed to produce high quality core images that
will meet the needs of many users. However, this
system lacks some features that may be found in
more advanced core-imaging systems. For details on
more advanced imaging systems, readers should
consult technical publications and resources from
labs that are equipped with such systems, such as the
Limnological Research Center at the University of
Minnesota, Minneapolis (http://lrc.geo.umn.edu/),
and labs aboard Ocean Drilling Program ships (e.g.
Merrill and Beck 1995; Nederbragt et al. 2000).
The system presented in this paper consists of both
hardware used to collect photographs and software to
K. McMillan
Department of Geological Sciences, University of
Saskatchewan, 114 Science Place, Saskatoon, SK, Canada
K. McMillan (&)
2501-123 10 Ave. SW, Calgary, AB, Canada T2R 1K8
e-mail: km1138@yahoo.ca
Present Address:
K. McMillan
16 Shawcliffe Bay SW, Calgary, AB, Canada T2Y 1H1
123
J Paleolimnol (2008) 40:1179–1184
DOI 10.1007/s10933-008-9223-5
process the digital images. The hardware consists of
two parts: (1) a rig to which a personal digital camera
is mounted (as on a tripod) and (2) a track for holding
a split core and the camera rig in-line (Fig. 1).
A user manually photographs the core, moving
either the camera rig (‘‘core-stationary mode’’) or the
core (‘‘camera-stationary mode’’) in small increments
(1–2 cm) between photographs (see ‘‘Image collec-
tion: core-stationary versus camera stationary
modes’’ section); the exact spacing between photos
is not important because the final composite image is
created by image-matching software. Shorter inter-
vals between captures yield better results, but longer
intervals use less camera memory.
All dimensions quoted here are from the unit
constructed at the Department of Geological Sci-
ences, University of Saskatchewan, although the
dimensions could easily be modified. Imperial units
are used where construction materials are designed to
such specifications (e.g. 1/4-inch bolts), but otherwise
metric units are given.
The software used in this system is available either
commercially or from public domain. The only nec-
essary processing steps are cropping images and
compositing individual captures into a single core
image. However, some users may also wish to colour
calibrate and/or greyscale calibrate their images for
greater accuracy (see ‘‘Colour and greyscale calibra-
tions’’ section). Several freely available software
packages can be used for image analysis of the final
core image, e.g. Scion Image� (http://www.scioncorp.
com) or ImageJ (http://rsb.info.nih.gov/ij/). Other
freely available programs that users may find helpful
are Coralyzer (http://www.evl.uic.edu/cavern/corewall),
which allows visualization and annotation of core
images, as well as stratigraphic overlaying with other
core data, and PSICAT (http://portal.chronos.org/
gridsphere), which allows users to create multi-data-
set stratigraphic columns from core data.
System components
Track
The track consists of a plywood sheet (1 m long by
47 cm wide) with elevated inner ridges (also ply-
wood, fastened by wood staples) for holding the core
in place, and outer ridges for keeping the camera rig
in-line. A height of 1.5 cm and spacing of 3.5 cm for
the inner ridges is used so that cores with diameters
of about 5–12 cm can easily be accommodated. The
outer ridges are also 1.5 cm high.
Multiple 1-m-long segments of track make storage
easier than a single unit several meters long; four
1-m-long segments can be built from a standard
80 9 40 (1.2 m 9 2.4 m) sheet of plywood. About
12 cm should be left between the end of the core and
the end of the rig so the rig does not roll off the track
during the first or last few captures when operating in
core-stationary mode.
Camera rig
The camera rig is made from standard 200 9 400
lumber and four pre-made wooden wheels (used only
in core-stationary mode). The rig consists of two
trucks bridged by a horizontal crossbar to which a
handheld digital camera is mounted.
Each truck consists of a 20-cm-long horizontal bar
with a 40 cm vertical leg bolted to it. Each horizontal
bar is a piece of 200 9 400 lumber with two 5.5-cm
wheels attached to the outer side by 1/4-inch-
diameter bolts. Each vertical leg consists of two
4.2-cm-wide boards separated by 1/4 inch (to
accommodate the 1/4-inch bolts extending from the
crossbar; see next paragraph); 4.2 cm was chosen for
the board width, to create flush-edges.
The crossbar consists of a 28-cm-long 200 9 400
board with a 1/4-inch-diameter bolt, extending 1/4
inch out of the board, in the middle for mounting the
Fig. 1 Camera rig and track with components as referred to in
text. Upper left inset shows rig disassembled
1180 J Paleolimnol (2008) 40:1179–1184
123
camera (which will have a threaded hole in the
bottom for this purpose), and two 1/4-inch-diameter
end-bolts extending about 4.5 cm from each end for
mounting the crossbar to the vertical legs. The end-
bolts can be fixed in the crossbar by sawing the heads
off four 1/4-inch-diameter bolts and gluing them into
pre-drilled holes in the ends of the crossbar (using
Liquid NailsTM Steel and Metal Framing Adhesive or
a similar wood-metal adhesive) or by fasteners with
screws on one end and bolts on the other. Because
each vertical leg is split along its entire length, the
crossbar can be fixed at any height.
The rig is designed to fit snugly within the track; if
side-to-side movement does occur while rolling,
additional washers can be placed between the wheels
and the trucks to act as spacers.
Scale
All core photographs require an accurate scale for
spatial reference. A length of metal tape measure
works well because it is lightweight and virtually any
length of scale can be created. A nylon tape measure
glued to a flat aluminum dowel also works well, but
should be checked against a ruler after gluing to
ensure it has not been stretched. The scale must be
held at the same height as the split core surface,
otherwise true distances along the core will be greater
than indicated by the scale if it is below the core
surface, and less than indicated if the scale is above
the core surface; the difference in height may also
cause either the scale or the core to appear slightly
out of focus. Figure 2 shows the system in use, with
the scale in place.
Image collection and processing
Image collection: core stationary versus
camera-stationary modes
The system may be operated by moving the core down
the track between successive captures with the camera
fixed in place (camera-stationary mode) or by moving
the camera along the length of the core between
successive captures (core-stationary mode). The main
advantage of camera-stationary mode is that lighting
on the core is constant for each photo, relative to the
camera; thus effectively eliminating the possibility of
uneven illumination of the final core image. The main
advantage of core-stationary mode is that it is more
compact, as the track needs only to be slightly longer
than the core, instead of twice as long.
In core-stationary mode, the scale can be fixed
directly to the core barrel, or propped up next to the
core at the same height as the sediment surface; non-
setting modeller’s clay (PlasticineTM) works well for
propping up the scale; putty (e.g. plumber’s putty,
Silly PuttyTM) is more ductile and may deform under
the weight of the scale.
When operating in camera-stationary mode, the
wheels on the camera rig should be removed or
immobilized with putty, and the scale must be
attached directly to the core barrel. The track should
still be used in camera-stationary mode, because
without it, keeping the core in a straight line between
captures is difficult, and even small deviations may
impede proper photo-compositing. For short cores
(a few metres or less) no rolling mechanism is
necessary to slide the cores along the track. For
longer cores, a series of rollers along the track may
ease operation. Care should be taken to crop all
background out of individual captures, as the back-
ground image will not change systematically with
core position as it does in core-stationary mode; a
discrepancy between core images and background
may also impede proper photo-compositing.
Since either mode may be employed with virtually
no hardware changes to the system, users may choose
to operate in core-stationary mode at some times (e.g.
when photographing core in the field), and switch to
camera-stationary mode at other times.
Fig. 2 Camera rig (seated in track) in use (camera-stationary
mode). Note the scale (mounted with modeller’s clay), and the
digital camera mounted to the cross bar
J Paleolimnol (2008) 40:1179–1184 1181
123
Lighting and camera settings
Different lighting arrangements were experimented
with, and the best results were achieved with
fluorescent room lighting augmented with halogen
spot-lighting. LED lamps were found to be a poor
light source because they do not actually emit white
light, but rather a pale blue light that is poorly suited
to colour photography. Room lighting, used alone,
may be too dim for good photo exposure and may
yield inconsistent shadow effects; however, these
problems can be eliminated by using bright spot-
lights. Care should be taken not to overexpose the
core to spot-lights because the surface of the core
may quickly dry out. Illumination should be as
homogenous as possible to minimize the brightness-
gradient along the core, particularly if using spot-
lights. If necessary, uneven illumination can be
corrected by post-photography processing techniques,
although such corrections may alter real tonal vari-
ations in the image, and may not fully rectify the
heterogeneous illumination (e.g. Nederbragt et al.
2000; Nederbragt and Thurow 2005).
Wet cores often provide the clearest images of
sedimentary structures and fabric; however, surface
glare may prevent proper photo exposure and obscure
parts of the core. The simplest, though not necessarily
most effective way to solve this problem, is to
carefully cover the surface of the cores with trans-
parent plastic film (e.g. kitchen-wrap) (Renberg
1981). Cross-polarization, a more effective technique
for glare-reduction, is discussed elsewhere (e.g.
Lamoureux and Bollmann 2005), but may be difficult
to implement with a personal camera.
The camera should be set to manual exposure, full
colour and maximum sharpness. Many commercial
digital cameras do not offer manual focus, but macro-
focus works reasonably well. The flash should be
turned off. White balance should be set manually by
calibrating the camera with a true white reference
held under the same lighting conditions as the core;
auto-white balance settings may yield inaccurate and
inconsistent tones in photographs, particularly if no
white tones occur in the photo, or if more than one
distinct white tone occurs (e.g. nearly-white sediment
and a white depth-scale).
Exposure needs will vary, depending on the core
being photographed. Cores with alternating dark and
light couplets are particularly difficult to photograph
because parameters must be set so as not to overexpose
the lighter laminae, but also not underexpose the darker
laminae. Users must experiment with different shutter
speeds and aperture diameters (measured in F-numbers
or F-stops) to find an ideal setting for their core.
Unfortunately, most personal digital cameras do not
allow users to set both the shutter speed and F-number
at the same time, and changeable lenses are an unlikely
option, so some trial and error will be necessary to find
the best possible exposure parameters.
Colour and greyscale calibrations
Colour and greyscale calibration is recommended,
particularly if images are to be used for image
analysis. A small colour-checker plate with a set of
known colours and grey-shades, such as the X-Rite/
Gretag-MacbethTM ColorChecker Mini, should be
imaged with every capture to act as the set of
Fig. 3 Schematic diagram
showing relative zones of
distortion of a vertical
downward-facing
photograph
1182 J Paleolimnol (2008) 40:1179–1184
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reference standards. The plate should be visible in
every photograph so that each captured image can be
colour-calibrated before compositing. The plate
should not be visible in the final composite image,
so care should be taken to place it in a spot that will
be cropped from each individual capture. The actual
calibration can be done using imaging software such
as Scion ImageTM or ImageJ, although add-on macros
may be necessary to perform the task. For more
detailed discussions of colour and greyscale calibra-
tions, see Nederbragt et al. (2005) and Ortiz and
O’Connell (2005).
Image compositing
Vertical photographs of a flat surface are increasingly
distorted as one moves from the principal point
(directly below the centre of the camera lens) to the
edges of the frame (Fig. 3). Because photomontages
require minimally distorted source images, original
images should be cropped so that the most distorted
parts of the photographs are not included in the final
image (Fig. 4). Fortunately, because each photo can
be collected at the same size using a personal digital
camera, the image cropping process can easily be
automated using imaging programs such as ImageJ or
Adobe PhotoshopTM; detailed instructions for using
Adobe Photoshop CSTM are given in Appendix A.
Finally, core images are spliced together using
commercial panorama software. Several packages are
available, and I have found Panorama FactoryTM
(www.panoramafactory.com) to work very well with
a minimum of input commands, although other pro-
grams may work equally well. To minimize possible
image distortion, cylindrical projection should be
used, rather than spherical projection. Partial-
panorama should be selected, rather than full-
panorama, so the last picture in the batch is not
spliced with the first. No automatic image corrections
should be made by the compositing software.
Using the configuration described above, each
metre of core requires about 50–100 individual
photographs. If one collects 100 photos with a 4.1
megapixel camera, about 140 Mb of disk space is
used. Photography takes about 15 min to complete.
After cropping, photo compositing is done automat-
ically by the software, and takes about 5 min to
process (using a 1.86 GHz processor and 1.0 Gb of
RAM). As a reference, the final image is about 6 Mb
in size (at a resolution of about 100 pixels per mm2 of
core), although image size and resolution will depend
Fig. 4 Single original core photograph (shown without colour
calibration plate). Shaded areas are too distorted to use in the
final composite image (note that the ruler seems to move
farther away from the edge of the frame with distance from the
non-shaded part); therefore the image is cropped so that only
the non-shaded area is used
Fig. 5 Final composite
image created from 68
individual photographs
taken in core-stationary
mode (including the one
shown in Fig. 4)
J Paleolimnol (2008) 40:1179–1184 1183
123
on camera height and camera settings, as well as the
image colour-composition. Figure 5 shows an exam-
ple of a finished core image.
Acknowledgements Thanks to Tim Prokopiuk for logistical
support. Reviews by Dan Karasinski and two anonymous
reviewers were very helpful in refining the paper and the
hardware described within.
Appendix A
The following instructions detail how to crop multi-
ple images automatically using Adobe PhotoshopTM
(current to version CS3, December, 2007):
(1) Copy all individual photos from their original
location to a single folder. Keep copies of
original (unedited) images in case of unex-
pected problems during processing
(2) In Photoshop, open any photo to be cropped
(3) Select WINDOW… ACTIONS
(4) Select ‘‘create new action’’ from the small
icons at the bottom of the ACTIONS popup
(5) Give the new action a name, e.g. ‘‘Image
Cropper’’ and click the RECORD icon
(6) Crop the central, least distorted, part of the
photo so that about 1 or 2 cm of core length,
but 100% of the core width, is retained.
NOTE: Some overlap between adjacent
images is necessary for splicing; cropped
images should be slightly longer than the
increment spacing between images.
(7) Click the ‘‘stop recording’’ icon at the bottom
of the ACTIONS popup
(8) Close, but do not save the cropped image
(9) Select FILE… AUTOMATE… BATCH
(10) In the BATCH popup select the following
options:
a. In the ACTION menu select ‘‘Image
Cropper’’
b. In the SOURCE menu select ‘‘folder’’ and
choose the folder with the photos already
in it
c. In the DESTINATION menu, choose
‘‘save and close’’
d. Click OK
Photoshop will automatically open and crop all the
photos in the source folder and save them to the
destination folder. If images are being saved as
JPEGs, Photoshop may prompt the user to verify the
image quality settings each time a file is saved.
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