SLiDAP: The Satellite-Linked Data Acquisition and Photogrammetry System.

The concept of remote three-dimensional (3D) close range soft copy photogrammetry via the SLiDAP system:

The SLiDAP system is a semi-autonomous remote imaging network accessible via satellite data link. Each installation consists of a network of imaging stations capable of providing multiple high-resolution, time-synchronous digital still images form different perspectives, of specific objects of interest within a set viewing area. These images are automatically taken and then sent to the home lab for subsequent analysis. Using off-the shelf, commercially available software, spatially referenced virtual object models are constructed, from which accurate spatial measurements can be derived.

Take a look at a series of concept photos simulating SLiDAP images of a sea lion haulout area, on this page.

The primary functions the SLiDaP system is designed to perform are:

  1. Accurate year-round age-specific counts of sea lions at remote locations, up to several times per day. Age structure information will be based on volume estimates collected from individual animals.

  2. Repeated, accurate body mass estimates of individual sea lions based on three-dimensional photogrammetry. Body mass estimates will be used for long-term monitoring of mass trends of individually recognizable or tagged sea lions. Body mass trends will be analyzed for annual and ontogenetic changes, as well as changes across major fishing episodes.

  3. Repeated estimates of body condition trends based on photogrammetrically derived morphometric measurements.

  4. Once implantable, archival tags become available, use multiple SLiDaP systems to automatically download data from RAT-Link equipped mobile data recording tags.

Key system design criteria will center around extreme ruggedness, highest reliability with minimal service requirements, low temperature capability, complete independence from any local power and communications infrastructure, rapid system deployment capability, as well as very low environmental impact.

Local area coverage for the SLiDaP system wLAN will be set up for ¼ sq. km, but can be extended with modifications to cover larger circular areas or several km of coastline. Such extended areas may however impose certain restrictions on photogrammetric accuracy. Two separate satellite data links can be integrated into the SLiDAP system. Global coverage is provided through an INMARSAT remote system, for which access extends from the equator to 78 degrees latitude North and South. This covers most Antarctic coastlines and sub-Antarctic islands of interest for biological studies, as well as most arctic locations of biological interest: all of Alaska including the Aleutian Islands, Pribilof Islands in the Bering sea, most of the Canadian arctic and Greenland, all of Siberia and it's coastline, as well as both magnetic poles. The Northernmost portion of Greenland, Ellesmere Island, most of the arctic winter sea-ice cap and the core of the Antarctic continent are excluded. VSAT systems provide higher data throughput rates at substantially lower operating costs, but have more restricted coverage and higher power consumption rates. SLiDAP systems can be configured with one or two satellite links of each system.

The SLiDaP system is designed to operate in extreme environments, down to a lower temperature limit of -25 degrees C in initial the first development stage. At later stages operations down to -40 degrees ambient will be feasible. The imaging system has initially been designed for the visible spectrum, with low light level capability for dusk and dawn operations.

For details on 3D photogrammetry for contact free, remote spatial measurements and estimation of body mass and condition, take a look at < BODY COMPOSITION TELEMETRY > on the left menu, as well as details on 3D-photogrammetry under < TECHNOLOGY >, < ANALYTICAL APPROACHES >.

Check out details on RAT-Link under our < TECHNOLOGY > and < EXPERIMENTAL APPROACHES >.

 

© M. Horning 1999, 2000.

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