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Title
Systems for data processing, anaylsis and representation

70°30’S
1
E
70?31'
ent data
ouring
t data
ring

70°32
n. Exposed
ns of points
ing errors in
, which only
ore than the
block, the
ularly in the
lable control
nfortunately,
;ome of the
designed to
ed from the
good results
ince the left-
ol. However,
| dimension,
has proved
he left-hand
hat some of
large errors.
al error is
points with
he result is
os a better
rner is still
attempts to
strengthen control in the lower left corner but point 2004 is
apparently poorly located, and the errors are unacceptable.
The overall result of these tests was that the distribution of
control in test 5 represented the best that could be
achieved in this project. The results, while not comparable
with the levels of accuracy to be obtained in temperate
countries, are acceptable for mapping in this remote
region. À further advantage is that the relative accuracy of
measurements within the block is of the order of 1-2 m.
The lower absolute accuracy is less important for practical
use.
RESULTS
The output from the block adjustment was used with the
AP190 analytical plotter to extract heights from one of the
models of the block. Heights could only be reliably
extracted on ridge-lines, on exposed rock and where
crevasses or avalanche scars provided enough surface
detail for stereo-matching on ice-covered surfaces. These
elevations gave enough height control for the shape-from-
shading algorithm described above to be used to extend
contours onto the snowfields surrounding the central ridge.
The map created (fig. 3), with contours at an interval of
25 m, can be compared with an earlier map (fig. 4),
compiled at a scale of 1:250,000, which was the most
detailed line map of the area available prior to this work.
ACKNOWLEDGEMENTS
Dr. J. Sievers, Institut für Angewandte Geodäsie, Frankfurt,
provided the georeferenced TM image. Mr. A. Perkins and
Mrs J.W. Thomson, British Antarctic Survey, provided
much helpful discussion. Dr R. Kirby and Dr C. Place,
University of Edinburgh, were supervisors to RS during this
project, which was undertaken as part of her MSc course.
BIBLIOGRAPHY
Knight, J.A., 1986, Report on the adjustment of the British
Antarctic Survey Network: Cambridge, U.K., British
Antarctic Survey; Internal report. Ref. No. ES2 EW 300/38,
36 pages [Unpublished].
Mcintyre, N.F., 1991, Mapping ice sheets with the
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p. 1775-1793.
Rapley, C.G., Griffiths, H.D., Squire, V.A., Lefebvre, M.,
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