342
May 2019
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
Imagery Intelligence Agency, I received excerpts of a 1935
book entitled,
Die Karten der Cordillera Real und des Talk-
essels von La Paz (Bolivien)
. The authors were Prof. Dr. Carl
Troll, and the famous photogrammetrist, Dr. Richard Finster-
walder!Finsterwalder detailed his excellent terrestrial photo-
grammetric survey of the volcanoes around La Paz.
The “Topographic Desk of the Southeast” was combined
with the “Major General Topographic Cabinet of the State”
in 1936 to form the Instituto Geográfico Miliar (IGM). Initial-
ly formed in the city of Cuevo, the institute was relocated to
Cochabamba in 1939 and finally moved to La Paz in 1942. By
the end of 1948, “La Ley de la Carta” (The Law of the Map)
was decreed establishing IGM as the monopoly for mapping
the nation. I have discussed this concept common to many
Latin American nations as a vehicle to help fund the military
because of the low existing tax base. Argentina (see
PE&RS
,
December, 1999, pp. 1361-1363) and Ecuador (see
PE&RS
,
May, 1998, pp. 542-543) are no exceptions to this custom.
The southwestern portion of Bolivia is well controlled with
classical triangulation arcs, and some high-precision electron-
ic distance meter traverses cover the southeastern portion of
the country. The northern half of Bolivia is relatively devoid
of triangulation control. Vertical control does extend to the
northern provinces, and 1:50,000-mapping covers the south-
ern half completely and the northern latitudinal half of the
northern half.
The Republic of Bolivia is on the Provisional South Amer-
ican Datum of 1956 (PSAD 56) with the origin in the town
of La Canoa, Venezuela where Φ
o
= 08° 34´ 17.170˝ North,
Λ
o
= – 63° 51´ 34.880˝ West of Greenwich, and the defining
azimuth to station Pozo Hondo (α
o
) = 40° 22´ 45.96˝. The el-
lipsoid of reference is the Hayford 1909 where the semi-major
axis,
a
= 6,378,388 meters, and the reciprocal of flattening,
1
/
f
= 297. In 1977, James W. Walker presented and published
a paper at the Pan American Institute of Geography and His-
tory that included the seven-parameter transformation from
PSAD 56 in Bolivia to the WGS 72 Datumwhere: ∆X = +268.20
m,
Δ
Y = – 129.21 m,
Δ
Z = +408.13 m, scale = – 1.79024x10
-5
,
R
X
= – 1.549˝, R
Y
= – 0.742˝, and R
Z
= – 0.416˝. However,
Walker pointed out that the rotations and scale factor had
magnitudes equal to the uncertainty, so the actual parame-
ters had little to do with reality. For that reason, the transfor-
mation parameters from the South American Datum of 1969
(SAD69) coordinates for Bolivia to the WGS 72 Datum were
only offered in terms of three parameters. I have not been able
to locate anything in Bolivia that is referenced to SAD69.
All late 20
th
century large-scale mapping of Bolivia appears
to be referenced to the PSAD 56. The Grid of choice for Bo-
livia is the Universal Transverse Mercator (UTM). Howev-
er, a Lambert Conformal Conic does exist in Bolivia that is
referenced to the WGS 72 Datum where the Northern Stan-
dard Parallel
j
n
= – 12° South, the Southern Standard Par-
allel
j
s
= – 20° South, the False Northing Latitude of Origin
j
o
= – 20° South, the Central Meridian λ
o
= – 64° West of
Greenwich, and the False Easting is 500 km. The ellipsoid of
reference is the WGS 72 where a = 6,378,135 meters and the
reciprocal of flattening,
1
/
f
= 298.26. Other ancient Datums
known to exist in Bolivia include the Arequipa Astro from the
boundary surveys of the 19
th
century with Peru, and the Pepi-
to and Poto Astros. John W. Hager believes that the vertical
Datum is referenced to Arica in Chile.
U
pdate
Since 2001, Bolivia has entered into a cooperative agreement
for the Geocentric Reference System for the Americas, termed
“SIRGAS,” a Spanish acronym. Extensive geophysical re-
search has been initiated in Bolivia with respect to crustal
motion and volcanic activity. The CGPS network in coun-
try consists of 43 CGPS station sites, with 11 GPS stations
recently installed in response to the Pisagua 8.2 magnitude
earthquake on 1 April 2014. As of November, 2014 more than
240 GPS stations had been observed with dual-frequency GPS
receivers.
1, 2
Topography of the Uyuni salt flats determined with kinematic
GPS was published in 2008.
3
Significant gravity survey were published in 2015 for the Bo-
livian Central Andean Plateau,
4
but there seems to be zero
data publicly available on transformation parameters from
the PSAD 56 or the SAD69 datums to the current SIRGAS
system. The Bolivian military IGM offered no response to my
queries.
1
2 ht tps : / / pubs . geos c i encewor l d . org / gsa / geosphere /
article/14/1/65/525536/50-years-of-steady-ground-
deformation-in-the
3
4 h t t p s : / / e t d . o h i o l i n k . e d u / ! e t d . s e n d _
file?accession=osu1437668357&disposition=inline.
The contents of this column reflect the views of the author, who is
responsible for the facts and accuracy of the data presented herein.
The contents do not necessarily reflect the official views or policies of
the American Society for Photogrammetry and Remote Sensing and/
or the Louisiana State University Center for GeoInformatics (C
4
G).
This column was previously published in
PE&RS
.
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