78 PHOTOGRAPHY
‘Radius’ 1.2 and ‘Threshold’ 0. For images between
10 and 30 megabytes, ‘Amount’ 150, ‘Radius’ 1.5 and
‘Threshold’ 0.Mosaics – Photo or Video
Ideally, a mosaic should not be the primary means of sur-
vey but should be carried out to complement or assist it
and fill in detail. If this is not possible, due to limitations
of depth and dive time, then as a minimum some check
measurements should be taken and used in the prepara-
tion of the final mosaic.
The main reason for producing mosaics is that often
the lack of visibility and clarity under water and/or the
scale of the site does not enable an overall picture of a
site to be taken. Instead, a series of overlapping images
must be taken which are then stitched, joined or merged
together (figure 10.6). Traditionally this has been done with
printed images but now images can be scanned (unlessFigure 10.6 A 5 metre square (264 sq. ft) photomosaic of ship remains on the Duart Point wreck, made up of 25 indi-
vidually photographed 1 m blocks. (Photo: Colin Martin)