Rt. Bird et al., MERGED GLORIA SIDESCAN AND HYDROSWEEP PSEUDO-SIDESCAN - PROCESSING AND CREATION OF DIGITAL MOSAICS, Marine geophysical researches, 18(6), 1996, pp. 651-661
We have replaced the usual band of poor-quality data in the near-nadir
region of our GLORIA long-range sidescan-sonar imagery with a shaded-
relief image constructed from swath bathymetry data (collected simulta
neously with GLORIA) which completely cover the nadir area. We have de
veloped a technique to enhance these ''pseudo-sidescan'' images in ord
er to mimic the neighbouring GLORIA backscatter intensities. As a resu
lt, the enhanced images greatly facilitate the geologic interpretation
of the adjacent GLORIA data, and geologic features evident in the GLO
RIA data may be correlated with greater confidence across track. Featu
res interpreted from the pseudo-sidescan may be extrapolated from the
near-nadir region out into the GLORIA range where they may not have be
en recognized otherwise, and therefore the pseudo-sidescan can be used
to ground-truth GLORIA interpretations. Creation of digital sidescan
mosaics utilized an approach not previously used for GLORIA data. Pixe
ls were correctly placed in cartographic space and the time required t
o complete a final mosaic was significantly reduced. Computer software
for digital mapping and mosaic creation is incorporated into the newl
y-developed Woods Hole Image Processing System (WHIPS) which can proce
ss both low- and high-frequency sidescan, and can interchange data wit
h the Mini Image Processing System (MIPS) most commonly used for GLORI
A processing. These techniques are tested by creating digital mosaics
of merged GLORIA sidescan and Hydrosweep pseudo-sidescan data from the
vicinity of the Juan Fernandez microplate along the East Pacific Rise
(EPR).