Megapixel Shows Amphibian in Detail
Images enable research on European cave salamander in dark, humid environment
- By Del V. Salvi
- Oct 01, 2011
The Tular Cave Laboratory in Slovenia was established in
1960 by Marko Aljancic, a biologist specializing in subterranean
species. Aljancic populated the laboratory with the European
cave salamander (Proteus anguinus), a blind amphibian
that dwells in the subterranean waters endemic to the
Dinaric Karst, a topography characterized by subterranean
limestone caverns carved by groundwater. The Dinaric Karst
spans eastern Italy through Slovenia, over coastal Croatia to
Bosnia-Herzegovina. The seriously endangered salamander
can live up to 100 years, is the only European cave vertebrate
and, at about 10 to 12 inches long, is by far the largest cave
animal in the world.
Tular is the biggest cave laboratory in Slovenia and one of the
few places where the endangered European cave salamander has
been successfully bred outside its natural habitat. The laboratory
also maintains a colony of an extremely rare dark-pigmented
subspecies endemic to Slovenia. The cave laboratory has studied
the ecology and behavior of the salamander, primarily its breeding,
for more than 50 years. Conditions at the site include total
darkness and near-100 percent humidity.
The laboratory maintains 40 salamanders in four large laboratory
pools to simulate their natural cave environment, with clay
on the bottom and rocks for hiding. Experiments are based on
observation and are carefully designed not to harm or stress the
animals. The laboratory is a constituent body of Slovenia’s Cave
Biology Society and is led by Gregor Aljancic.
A real-time and long-term video monitoring system was needed
to observe behavioral experiments and to obtain adequate
information on the salamanders’ behavior. The system needed
to employ motion-detection to avoid capturing useless video of
long periods of inactivity, and it also needed to reasonably balance
video data quantity, quality and required storage capacity.
The clear details would provide additional information to help
the laboratory design new studies. The system would need to use
infrared (IR) light so as not to disturb the animals, which become
stressed when their skin senses the visible spectrum of light.
Eventually, the system would need to incorporate five to seven
cameras that would be permanently mounted and combined
into a 24/7 monitoring system accessible over the Internet as the “TularVirtualLab.”
From the fall of 2009 to the spring of
2010, the Tular Cave Laboratory searched
the market for a video camera to meet its
needs, especially the need for high-resolution
images. Arecont Vision’s AV5105DN
5-megapixel camera was the only one to
fit the criteria. Laboratory officials also
preferred a U.S.-made product because
they desired quality and durability in the
extreme cave conditions.
Video monitoring of salamander behavior
began with shorter behavioral experiments
of up to 30 days, with the system
removed from the simulated cave once
the experiment was finished. The laboratory’s
AV5105DN camera, equipped with
a 4.5-13mm varifocal IR lens, is connected
to a computer running Arecont Vision
AV100 software as the video management
system. The camera is mounted directly
above the monitored pool—3 to 6 feet
away—or experimental aquarium—1 to 3
feet away. Because of high humidity and
dripping water, the camera is enclosed in a
plastic, waterproof housing. The software
provides video recording based on motion
detection triggered by the salamander.
The AV5105DN day/night camera
used at the laboratory includes a motorized
IR cut filter for low-light conditions.
The camera incorporates Arecont’s Mega-
Video image processing at 80 billion operations
per second and can output multiple
image formats, allowing simultaneous
viewing of full-resolution field-of-view
and regions of interest for high-definition
forensic zooming.
Other components of the system include
a universal power adapter, connection
to a PC using a standard UTP cable,
and a PC placed in the laboratory’s control
room running the software to serve
as a video-image recorder and provide
temporary storage. Wireless transmission
was ruled out because it could stress the
electroreceptors in the salamanders’ sensory
systems. Every two or three days, the
data is transferred (via an external hard
drive) to a main hard drive archive in a
remote location.
Several IR LED illuminators of various
intensities provide illumination to expose
the entire area equally. High absorption of
IR light in the water requires higher illumination
for deeper areas. When observing
macroscopic details, such as hatching,
the camera is mounted on the video port
of a stereo microscope. Gregor Aljancic
designed and installed the system.
The laboratory plans to install the permanent
system by the end of the year, using
five to eight cameras with 24/7 monitoring
tied to an Internet connection to
the cave. Remote IR video monitoring via
the Internet will minimize the potential
negative impact on the animals caused by
factors such as human presence, noise and
radiation from the electronic equipment.
The change also will relocate the sensitive
electronic equipment from the harsh
cave environment to a remote location.
A wireless access point will be installed
at the laboratory’s entrance. From that
point, data will pass throughout the lab
on a wired network, with a PoE network
switch providing power to each camera.
After an Internet connection is installed,
the server computer, including the PC and
high-capacity hard drives to store additional
data, will be moved to one of the
lab’s remote facilities.
Better Images
Higher-resolution megapixel images provide
more information and clearer details
that were not possible with the poor quality
of the previous analog system. The
megapixel advantage becomes especially
obvious when monitoring a large laboratory
pool, which requires the camera
to be farther away, with the lens set to a
wide angle to cover the entire area. On the
video, the animals appear smaller, but the
megapixel camera still provides clear images
and allows digital zooming of moving
animals.
Advantages related to video management
include the ability to precisely
adjust the exposure settings using the
software, an improvement over the analog
system’s limitation of adjusting only
the iris and focus. Forensic zooming, the
ability to enlarge a smaller section of a
recorded video image and see additional
details, also is an important tool for both
online and offline viewing.
Viewing videotapes using the previous
analog system was time-consuming,
and roughly 70 percent of the gathered
video showed inactive animals, representing
a large amount of useless data
and a considerable and unnecessary
cost. Also, it was harder to find events.
Since 1998, the laboratory had digitized
the video images and used an online
video tracking software to analyze the
salamanders’ behavior. However, digitizing
the video further eroded the quality.
Also, the system was not efficient in
low-light conditions and lacked the necessary
detail when observing the whole
pool. The use of a megapixel camera
minimizes these challenges.
The use of a digital system also reduces
the cost of archiving data. Instead
of recording on expensive video tapes, the
transition to a hard drive archive provides
numerous options to optimize available
storage capacity.
In addition to the direct advantages of
megapixel video—image quality, capacity
to monitor details and motion detection—
the cameras provide some indirect
advantages. Incorporating up-to-date
video monitoring technology into the research
methodology raises the quality of
the research and advances the position of
the Tular Cave Laboratory in the scientific
community. In addition to providing
greater megapixel image quality, the use
of remote accessibility will open new possibilities
in science and education. To date,
the Tular Virtual Lab is believed to have
the first 24/7 video system.
During a one-month, 24/7 monitoring
test in January 2011, the camera mounted
above one of the laboratory pools captured
a female salamander laying eggs—
an extremely rare event that happens only
every eight to 12 years in captivity
Even in the early stages before the system
is fully operative, the value of megapixel
imaging as a study tool has become
obvious. The data collected by the infrared
cameras has already brought urgently
needed international attention to the
natural history and conservation of the
endangered cave amphibian. Developing
additional basic knowledge of the salamander
lays the groundwork for a more
relevant and effective conservation plan
for the endangered species.
This article originally appeared in the October 2011 issue of Network-Centric Security.