A suite of complementary survey tools aimed at producing 1-cm resolution
bathymetric models co-registered with 2-mm pixel color photography has
been assembled. The design goal is to produce quantitative documentation
of both geological and biological features that will allow change over
time to be assessed at vertical and lateral scales approaching one
centimeter. The current suite of tools combines multibeam sonar, stereo
cameras with dual xenon strobes, lidar, and an inertial navigation
system (INS) aided by Doppler velocity log (DVL). This sensor package is
mounted beneath remotely operated vehicles (ROV) and used to map the
seafloor from low altitudes. A 100-m by 100-m survey can be accomplished
in a single ROV dive. All surveys are conducted with scripted
station-keeping control loops operating on the ROV, resulting in more
efficient area coverage through tended automation.

Fine scale surveys of a chemosynthetic biological community at 2850-m
depth show that individual clams can be observed in both lidar
bathymetry and photographic imagery. Repeat surveys over multiple years
have been conducted in the morphologically active floor of Monterey
Canyon. Comparison of these data resolve subtle transitions from
depositional to erosional textures, and reveal the changes associated
with frequent sediment transport events down the active canyon. The
rocky, high relief environment of Sur Ridge offshore California hosts
sponge and deep water coral habitats. Here the combination of acoustic
and optic sensing proves particularly useful for quantitatively
characterizing the benthic community. The multibeam sonar measures
bathymetry without sensing soft animals, while the lidar measures a
surface that includes these animals. Subtracting the multibeam
bathymetry from the lidar bathymetry maps the locations and sizes of
soft animals.
