Optimal lab setup
● DSLR with several suitable lenses (see
above). For the controlled conditions of a
laboratory, the maximum resolution sensor
camera should be acquired for optimal
model resolution. An adjustable camera
stand may be necessary for macro lenses
that do not have a focus ring.
● Remote shutter release to avoid vibrations.
● Polarizing filter. Allows reducing reflections
on specimens that have shiny surfaces.
● Tripod (large and solid) with ballhead for
easy adjustment.
● Reflectors.
● Flash array (optional).
● Light/LED setup with several rows of focused
LEDs for even lighting of specimens (can be
combined with or used instead of reflectors).
● Neutral white/black background (can be
made from white/black cardboard,
professional drapes preferred) or (ideally)
green-screen, and sheets with printed
patterns with human-recognizable features
(e.g., black-on-white text pages or colorful
advertising supplements).
● Turntable (potentially motorized) with
featureless cover and degree markings on
the vertical outer surface. Note that
continuous turning is not desirable, so that a
motorized turntable needs to be computer controlled
and stoppable at predefined
intervals.
● Glass/perspex cubes of many sizes for
specimen support.
● White packing foam (tiny bubbles, so no
points can be found by the program) and
putty for specimen support.
● Scales with centimeter and millimeter
markings in various sizes, non-reflective.
A permanent lab setup aimed at rapid and
optimal quality digitizing offers the advantage
that the photography kit can be optimized for
best photograph quality and suitability for
photogrammetric reconstructions, without any
concessions regarding ambient lights or
background.
A key decision to make is whether to use a
flash setup or strong lights. Stronger lights
allow lower ISO values and shorter exposure
times. However, if a specimen is shiny (e.g.,
has been covered with lacquer or has a
crystalline surface) the photographs will show
variations in color or even light spikes from tiny
reflections. In this case, directional light or the
use of flashes can ameliorate or worsen the
problem, thus it is necessary to experiment.
The ideal background for easy model creation is
a green-screen, placed sufficiently far back that
reflected light from it does not fall on the
specimen. Evenly lit it can be selected with a
magic wand tool in the photogrammetry
software or a graphics editing program and
masked/deleted. White or black cloth or even
cardboard can also be used, but it is harder to
light it so evenly that magic wand tools are
effective. However, if the background is
featureless, the photogrammetry software will
not be able to pick up points anyways. The
color of the background, black or white, must
be chosen with the lighting of the images in
mind. A white background for a very dark
(coal) fossil will either lead to underexposure of
the fossil, or white glare around the fossil's
edges. In such cases, a black background is
preferable.
As discussed below, for specimens on which
few features are detected by the
photogrammetry program, a highly structured
background can be used to improve alignment
at the cost of time spent for masking or
cropping later in the modeling process.
A motorized turntable that rotates continuously
and slowly (then, very short exposure times
are required), or rotates a fixed small angle
and then remains stationary for a short time,
obviates the need of someone stepping and
reaching into the picture between shots.
If very rapid turnaround times are desired it is
possible to use several cameras
simultaneously. However, achieving even
lighting is then difficult. Currently, efforts are
underway to produce an automated 3D
digitizing line that uses many cameras and
mobile lights for photogrammetry and other
techniques (Santos, 2013). However, this and
similar set-ups are (yet) not sufficiently mobile,
not variable in the optics used and not
affordable for individual scientists' needs.