Slovenian laboratory uses megapixel cameras to observe rare amphibian

Arecont Vision cameras enable research on European cave salamander in dark, humid environment

Arecont Vision's AV5105DN is a 5 megapixel day/night camera that provides 2,592 x 1,944-pixel images at 9 frames-per-second (fps). Light sensitivity is 0.3 lux at F1.4. The camera uses H.264 (MPEG-4, Part 10) compression to minimize system bandwidth and storage needs. The AV5105DN can also be used at lower megapixel resolutions for various frame rates up to full motion. The camera provides full-motion progressive-scan 1280 x 1024 video at 30fps, 1600 x 1200 video at 24fps or 2048 x 1536 at 15fps. Features include forensic zooming to zero-in and view the details of a recorded image, motion detection and image cropping. The camera's day/night version used at the Tular Cave Laboratory includes a motorized infrared (IR) cut filter for superior low light performance. The camera incorporates Arecont Vision's MegaVideo(r) image processing at 80 billion operations per second. The AV5105DN can output multiple image formats, allowing the simultaneous viewing of the 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 AV100 software, serving as a video-image recorder and providing temporary storage. (Wireless transmission was ruled out because it could stress the electroreceptors in the Proteus sensory system). Every two or three days, the data is transferred (via an external hard drive) to a main hard-drive archive installed in a remote location.

Illumination is provided by three or four IR LED illuminators of various intensities 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 AV5105DN 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 2011, using five to eight cameras with 24/7 monitoring and tied into an Internet connection to the cave. Remote IR video monitoring via the Internet will minimize the potential negative impact on the animals due to factors such as human presence, noise and radiation from the electronic equipment. The change will also relocate the sensitive electronic equipment from the harsh cave environment to a remote location. A wireless access point will be installed at the entrance of the laboratory. From that point, data will pass throughout the lab on a wired network, with a Power-over-Ethernet (PoE) network switch providing power to each camera. After installation of an Internet connection, the server computer - including the PC and high-capacity hard drives to store additional data - will be moved to a remote facility of the Tular Cave Laboratory.

Megapixel Benefits

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 for digital zooming of moving animals.

Advantages related to video management include the ability to precisely adjust the exposure settings using the AV100 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, is also an important tool both for online and offline viewing.

Viewing videotapes using the previous analog system was time-consuming, and roughly 70 percent of the gathered video showed animals that were not active, representing a huge amount of useless data and a considerable 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 behavior of Proteus. 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.