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Systems for data processing, anaylsis and representation

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t data

n. Exposed
ns of points
ing errors in
, which only
ore than the
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ularly in the
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;ome of the
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ed from the
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ince the left-
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he left-hand
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os a better
rner is still
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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
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.
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.
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
altimeter: International Journal of Remote Sensing, v. 12,
p. 1775-1793.
Rapley, C.G., Griffiths, H.D., Squire, V.A., Lefebvre, M.,
Birks, A.R., Brenner, A.C., Brossier, C., Clifford, L.D.,
Cooper, A.P.R., Cowan, A.M., Drewry, D.J., Gorman, M.R.,
Huckle, H.E., Lamb, P.A., Martin, T.V, Mclntyre, N.F.,
Milne, K., Novotny, E., Peckham, G.E., Schgounn, C.,
Scott, R.F., Thomas, R.H., and Vesecky, J.F., 1983, A
study of satellite radar altimeter operation over ice-covered
surfaces: ESA Report 5182/82/F/CG(SC). 224pages.
Renner, R.G.B., 1982, An improved gravity base-station
network over the Antarctic Peninsula: British Antarctic
Survey Bulletin, No. 51, p. 145-149.
Rouy, E., and Tourin, A., 1992, A viscosity solutions
approach to shape-from-shading: SIAM Journal of
Numerical Analysis, v. 29, no. 3, p. 867-884.
Sievers, J., Grindel, A., and Meier, W., 1989, Digital
satellite image mapping of Antarctica: Polarforschung, v.
59, p. 25-33.
Thomson, J.W., and Cooper, A.P.R., 1993, The SCAR
Antarctic digital topographic database: Antarctic Science,
V. 5, p. 239-244.