A PHOTOGRAMMETRIC SURVEY OF HOSEASON GLACIER

Journal of Glaciolog)'J VO!'
A
12,
No. 64, 1973
PHOTOGRAMMETRIC SURVEY OF HOSEASON
KEMP COAST, ANTARCTICA*
By
P ETER
J.
GLACIER,
MORGAN
(Department of Geodetic Science and Institute of Polar Studies, Ohio State University,
Columbus, Ohio 43210, U.S.A. )
ABSTRACT. A stud y of Hoseason Glacier was made to test wh ether photogramm etry could yield meaningful glaciological information from repea ted series of a ir photogra phs without ground control. Three maps
indicate that large time differences, different camera systems, a nd the use of sea ice as a level d atum do not
presen t insurmountabl e difficulti es in photogrammetric reduction . Surface horizontal movement was
determined a nd level profil es were compiled . Hoseason Glacier is proba bl y in equilibrium.
R ESUME. Ulle etude photogrammetrique de Hoseasoll Glacier, K emp Coast, Antarctique. On a execute un e e tude
du Hoseason Glacier pour voir si la photogra mme trie pou va it apporter des inform ations glaciologiques
significati ves a pa rtir de seri es success ives de couvertures pho tographiques aeri enn es sans contro le a u sol.
Trois cartes prouvent qu ' un large echelonnement des vues dans le temps, I' usage d e differen ts types de
camera e t l'utilisation de la glace ma rine comm e nivea u de reference ne conduisaient pas a d es difficultes
insurmo ntables pour la res titution photogramme trique. Le de placemen t horizo nta l d e la surface a e te
de term ine et d es profils ca lcul es en ni vell ement. L e Hoseason Glacier es t probabl ement en equilibre.
ZUSAMMENFASSUNC. Eille plzotogrammetrisclze Vermessung des H oseasoll Glaciers, Kemp Coast, Alltarktika.
Am Hoseason Glacier wurde eine Untersucbung angestellt, um zu prufen, o b die Photogramme tri e a us
wiederholt a ufge nom menen Luftbildreih en oh ne F estpunkte am Boden glazio logisch verwertbare 1nformationen liefern kann . Drei K a rten zeigen, dass grosse Zeitunterschiede, verschiedene K amerasysteme und die
Benutzung d es Meereises als Ausgangsniveau bei der photogrammetrisc hen Auswertung keine unuberwindlic hen Schwierigkeiten bieten. Die hori zon tale OberAachenbewegung und Hohenprofi le wurden ermittelt.
D er Hoseason Glacier ist wahrscheinlich im Gl eichgewic ht.
I NTROD UCTIO N
Photogrammetric surveys of Antarcti c glaciers for glaciological studies date from 1957
when M elIor (1958) determined surface velocities on Hoseason Glacier, Kemp Coast,
Antarctica, over a short time interval and noted the general applicability of the m ethod .
Since then, methods of aerial and terrestrial photogrammetry have grown in importance in
Antarctica and have been used by many workers, e.g. Adler ( 1963 ), Cheremnykh ( 1962 ),
Weissman (1964), and Morgan ( 1970). Most of these studies, however, have used similar
camera configurations, some degree of geodetic control and intervals of about one year.
Coastal areas of Antarctica between long. 500 and 75 0 E. have been rep eatedly photographed by Australian National Antarctic R esearch Expeditions (ANARE) using 150 mm and
90 mm focal lengths, 230 X 230 mm format cameras at different times. The time interval
between two sets of photographs is in some cases as great as 1500 days. The problems posed by
lengthy time intervals and different cameras, coupled with lack of normal geodetic control ,
made it uncertain whether valid information could be extracted from the photographs. A
study was undertaken in ' 965 of the feasibility of extracting meaningful g laciological information from such photography.
The questions to be answered by this study are:
I. Can consistent absolute orientations be obtained from successive surveys despite a lack
of control and differing unknown distortions resulting from lack of knowledge of camera
interior orientation, refraction and film instability?
2 . Does glacier ice hold a recognizable form over such periods as to make surface velocity
deterrninations possible ?
* Contribution
No. 237 of th e Institute of Polar Studies, Ohio State University.
[ [3
114
JOURNAL
OF GLACIOLOGY
PHOTOGRAMMETR Y
H oseason Glacier (la t. 67 ° JO' S., long. 58° 20 ' E ., some 240 km wes t of Mawson ) was
chosen because:
I . R ep eated aerial photographic coverage was available, namely :
7 August 1957- KI7 camera
13 O ctober 1g60- RCg camera
20 January Ig65- Kq camera
2. The glacier is sm a ll a nd flanked by rock which could supply necessary relative planimetric control, while sea ice, which abuts the tongue of the glacier, could supply a needed
level datum and elevation control.
3. Limited plotter time was available, and it was n ecessary to choose a small area over
which profiles could be obtained without using aerial triangulation techniques.
The simpl e photogrammetri c reduction was accomplished without difficulty, using a
Wild A6 stereoplotter for the 150 mm photography and a K ern PG2 stereoplotter for the
go mm photography. Scale was obtained by using a single line scaled from a I : 40 000 map . *
For elevation control, sea ice was assumed to be a level datum 0 .3 m above mean sea-level.
Produ ction proceeded with a planimetric scale of I : 15840 and a contour interval of JO m
on the glacier. Th e resulting maps (Figs. I , 2 and 3) show changes in the long-term shape and
position of the glacier. An important aspect of reduction was the use of sea ice as a known
level da tum and also as an assumed elevation control. The sea-ice surface in all three instances
was assum ed to be 0.3 m above mean sea-level, based on an es timate of ice thickness. The
reliability of the assumption of constant sea-level can be gaged by referring to the rock area
to the east of the glacier (Figs. I, 2 and 3) over whi ch there is excellent agreement of contouring. This indicates that in an op en area where ocean tides are small , the assumption was
justified in the ab ence of tidal information. This is perhaps the most reliable means of
supplying elevation control for photogrammetric work n ear the coas t of Antarctica. An
alternative method of supplying control would be to use rock areas whose elevations had been
determined relative to some arbitrary level surface as datum . Unfortunately, this method
has the disadvantage that most often the distribution of rock is so limited that precision of
leveling of the model is inferior to the sea-i ce method; indeed , frequently no rock is visible.
From one time to the next it was possible to identify a number of points on the glacier
from which surface velocity could be determined.
1957
7 August
Number of p oints near edge of glacier
N umber of points n ear middle of glacier '
7
19 60
13 October
12
20
1965
J anuary
5
o
The selection of points 1 to 7 on the Ig57 survey and their subsequent identification on the
Ig60 survey was simple, as the edge shape of the glacier had changed very little over this
period (Figs. 1 and 2) . The sam e ease of identification with the single middle point was n ot
possibl e as the d eep snow cover during the Ig60 survey coupl ed with the long time interval
altered the appearance of the large crevasse on which this point was situated . There is n o
doubt, however, that the sam e crevasse has maintained its general shape over the intervening
period while moving in relation to the fixed rock east of the glacier. The additional points
8 to 12 on the I g60 survey and their reidentification, together with the identification of point
number 6 of the original survey on the I g65 photographs, allow estima tes to be made of the
• Un published map, scale
bourne, Australia.
I : 40000,
com pil ed by Antarctic Branch, Division of Natio na l M apping, M el-
PH OTO GR A MM ET RI C SU R VE Y
OF H OSEASO
11 5
GLAC I E R
surface velocity over a 7t year p eriod . It should be m ention ed that th e increased interval
between the 1960 and the 1965 surveys made the photointerpreta tion task more difficult.
Although the stress environment of H oseason Glacier m ay be expected to produce a
sequence of broadly similar features in tim e such as the crevasses along its eastern margin,
care was ta ken to t;eidentify the sam e feature and not m erely a similar feature. The agreem ent
of results with those of Mellor ( 1959) demonstrates that accurate reidentification is possibl e.
B'
~
z.
0
v
-z.
0
Cl
rn
v
-z..
"<
-..J
CC>
+ PT.O
8002
....
""---.
0
180
200
0
!,., I
Fig.
200
400
I
I
Hoseason Glacier. Photographic run 73, Nos. 800218003 taken on 7 August 1957 with Kl 7 camera. Contour interval:
10 m.
T.
JO U R NAL OF GLACIOLOGY
11 6
-+ PT.OA
817'0
f.
o·
180·
200
!
Fig .
2.
IO
•
0
"
I
200
I
400
,
600m
,
Hoseason Glacier. Photographic TUn 2R, Nos . 8 [70/8 [72, [3 October [960 with R C9 camera. COlltour interval :
m.
PHOTOGRAMMETRIC SURVEY OF HOSEASON GLACIER
ISO°
200
, ..
0
, J
200
I
400
!
600m
!
B
Fig. 3. Ho reason Glacier. Photographic run 6, Nos. 8033 Vj8034 V, 20 January [965 with K [7 camera. Contour interval :
10
m.
RESUL TS
Movement. The movements of 13 points were obtained by plotting the position of each
point at the time of each survey and measuring the distances between plotted positions.
These results are presented in Table I. The results for the period 7 August 1957 to 13 October
1960 are not significantly different from those determined for the period 13 October 1960 to
20 January 1965. No attempt was made to correct for ablation, for which no information is
available. The mean velocity for the edge of the Hoseason Glacier for the interval 7 August
1957 to 20 January 1965 was determined to be 0.74 m /day with a standard error of 0.02
ll8
JOURNAL
OF
GLACI0LOGY
m /day. The error of 0.02 m /day is almost entirely due to inacc uracies of m eas urement and
identification. This error is about 20 m at terrain scale, or 1. 3 mm at map scale. The velocity
for the center of the Hoseason Glacier was 1. 1 2 m /day for one time interval and one point.
It is estimated, due to greater uncertainty in identification of the point, that movement of
point "0" is probably in error by 2.5 mm at map scale, giving an error of 0.04 m /day at this
point.
TABLE
I.
FL OW RATES OF HOSEASON GLACIER
Point
No.
Glacier
position
0
centra l
edge
edge
edge
edge
edge
edge
edge
August
August
August
August
Aug ust
August
August
August
1957
1957
1957
1957
1957
1957
1957
195 7
to
to
to
to
to
to
to
to
October
October
October
October
October
O ctober
O ctober
October
1960
1960
1960
1960
1960
1960
1960
1960
12
edge
edge
edge
edge
edge
edge
October
Oct::>ber
October
October
October
1960
1960
1960
1960
1960
to J a nua ry
to J a nua ry
to Janua ry
to J an ua ry
to J a nua r y
1965
1965
1965
1965
1965
Average
6
edge
edge
A ugust 1957 to J a nuary 1965
I
2
3
4
5
6
7
Average
6
8
9
II
Interval
Period
days
Mo vement
m
163
163
16 3
16 3
1 163
I 163
I 163
I 163
1 307
847
885
86 9
861
89 1
853
86 9
Rate
mid
1.12
0.7 28
0.76 1
0·747
0 .74 0
0.766
0·733
0·747
I 163
15 60
15 60
1 5 60
15 60
15 60
86 7
,,8
154
152
124
,,8
0·744
0 ·7'7
0.740
0.738
0.7 2 1
0.7 17
134
971
0. 727
0.7 23
I
I
15 60
27 28
I
I
I
I
I
Ap/Jroximale
direction
02 5 0
0 10
0
0 10
0
0 [0 0
010 0
0 10 0
0 10 0
0 10 0
0 10
0
0 10 0
0 10
0
0 10
0
0 10 0
0 10 0
0 10 0
0 10
0
Average edge moveme nt ra te 0.74 ± 0.02 mid
These results differ by 10% from those d etermined by M elior ( 1959 ) but the difference
may be caused by factors other than changes in glacier movement. The most probabl e cause
is a difference in scale: the pre ent work used a value scaled from the compilation sheet, while
M elior used a principal point distance calculated from the ground speed of the a ircraft; either
of these scales may be in error. A consistent scale must be adopted for any set of data sequences.
Elevation control does not enter into the determination of horizontal motion and is not a
source of error.
Profiles. Transverse profiles of high precision can be made photogramme trically, but such
detail was not required in this study. Profiles have been constructed from contour data on the
topographic maps (Fig. 4). These profiles show that across line AA' the general shape of the
glacier is maintained with tim e. The position of the edge of the highest part of the glacier as
well as the average slope of the surface all remained constant over th e 7t year period. Additionally, the profile across line CD is not significantly different from those across AA'. This
indicates that there has been no major change in the transverse profile of the glacier. Similar
profiles (Fig. 4) are shown for the longitudinal line A'B'. The agreement between these
profiles is not as close as that obtained between transverse profiles, since surface slope in the
ice-fa ll region was steeper in 1960 than in 1957 and 1965. Moreover, the position of a local
maximum elevation is also different in the 1960 survey . The cause of these changes is not
known. Despite such small variations, it ap pea rs that over the 7t year p eriod of this study
the Hoseason Glacier was probably near eq uilibrium. The reproducibility of the rock contours
demonstrates that the assumed constancy of the sea-ice datum was adequate at the scale of
contouring used .
PH OT OGR A MM ET R I C
I~:-ti
-
f..,-'
S U RVE Y
(/)
w
H OSEASO'l
G L AC I ER
11 9
-"-------l- -f-l +t
-~
- -_,-_-~.
. ...L,..- C--__
50~
, __ -
OF
20 .'1/05
---1 3 / 10/60
7/ 8/57
~,.,>',~. .
'~ .
'"
- ,
O ~------------------------~~
' ------~
er
~
T::'
~
-15
~_ -~"'.
-.::---~
8'
. .
: :
- --
o
250 0
2011/ 65
--- 18 1 10/6 0
-
.~\\\\\.
".
7/8157
2000
J-
I',
1500
1000
500
DIS TAN CE Ill: MET RES
Fig. 4. Vertical profiles across Hoseason Glacier along lines
.J.~' ,
CD alld A ' B ' .
C ONC L USIO NS
Aerial p hotograph y can be used for glacio log ica l purpose, even when photographic runs
are sepa ra ted in time by m a n y years and utilize qu ite di ffe rent camera configuratiom . For
Hosea~o n G la cier, and probab ly fc r regions o f sim ila r sta!J ili ty, it appears tha t periods of three
years a re not too g reat for successful interpretations . As the time ir: terva l iccrea es, so too
does th e difficu lty of interpretation . ~atura l ice fea tur e~ suita ble for d etermin ing surface
movem ent are res tricted to ice marg ins and d istu r bed regiOles. A more comp lete movem ent
picture coul d be obtain ed by insta lling m a rkers. The install a tion of a fixed baseli ne is
essentia l for acc urate sca le control. For this purpose the method of I r.d epemlen t G eod etic
Con trol (Branc en l::erger, 1959; G hosh, 1962; M organ, 19 7 I) a ppears to be mos t practical.
However, in coasta l area~ it is not essentia l to supply verti ca l contro l because the sea ice offers
an excell en t na tu ra l datu m if tid a l d a ta are aV8.ilab le. F inally, pmfi le inform 2.tion d erived
from topographi c m a ps p ro, id es a toc l for the inves tigation of steady state and ma~~ balance
p rob lem s in remote a reas . Length y period s such as th e 7t years of this study can prov id e th e
gla ciol ogist with an insight into the nature of these p roblems, a lthough the acc uracy o f d eterm inati ons over long period s is limited I::y the q ua lity o f th e ph otointerpretati on.
A C K NOW LED G MENTS
T h is work was u nd erta ken at the Meteorology D epartm ent o f the U n ivel"s ity of M elbo ur ne
wh ile th e author was employed by Antarctic D ivision , D epartment of E xternal Affairs,
Melbourne, Australia . Photogrammetric eq ui pmen t wa~ mad e a va il ab le by the V ictori a
governmen t D epar tment of C rown La nds a nd Survey. Th e paper was completed at the
O hio State University where final typing, dra fting, a nd helpful discussions were provided at
the I nstitute of Polar Studi es .
MS. received 9 lvfay [969 and in revised form /8 Ju ly [.972
120
JOURNAL OF GLACIOLOGY
REFERENCES
Adler, R. K . 1963. Photogrammetric measurement of ice movement for glaciological studies of the Byrd Glacier, Antarctic
region, for the period I September 1962- 28 February 1963. Columbus, Ohio, Ohio State University. Research
Foundation. (RF Project 1543. Final R eport. )
Brandenberger, A . ] . 1959. Strip triangula tion with independent geodetic control; triangulation of strip quadrangles. Publication of the Institute of Geodesy, Photogrammetry and Cartography (Ohio State University), No. 12.
Cheremnykh, G. D. 1962. Novoye v izmerenii skorostey dvizheniya l'da v poverkhnostnykh chastyakh lednikov
po materialam aerofotos"yemki [New d evelopments in the measurement of the rate of movement of ice in the
surface parts of glaciers as shown by aerial photography]. Geodeziya i Aerofotos''yemka, No. 5, p. 111 - 15.
[English translation : Geodesy and Aerophotography, No. 5, 1962 [pub. 1963] , p. 342- 44.]
Ghosh, S. K. 1962. Strip triangulation with independent geod etic control. Photogrammetric Engineering, Vol. 28,
No. 5, p. 810- 18.
Melior, M. 1958. Photogrammetric flow m easurements on Antarctic glaciers. Transactions. American Geophysical
Union, Vol. 39, No. 6, p . 1158.
Melior, M. 1959. I ce flow in Antarctica. Journal of Glaciology, Vol. 3, No. 25, p. 377-85.
Morgan, P. J. 1970. I ce surface movement in M a rie Byrd Land. Ohio State University. Institute of Polar Studies.
Report No. 38.
Morga n, P. J. 1971. Rigorous adjustment of strips. Photogrammetric Engineering, Vol. 37, No. 12, p. 1271 - 83.
Weissm a n, S. 1964. The use of photogrammetric methods to investigate surface movement if the Antarctic ice sheet. Columbus, Ohio, Ohio State University. Research Foundation. (RF Project 1444. Fin al Report. )