394
June 2017
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
observed azimuths, and 49 latitude and telegraphic longitude
stations. The supplementary triangulation extended along
the shores of bays and harbors and up rivers and creeks. Most
of the coast triangulation was Third-Order accuracy, notably
the chain along the west and north coasts of Luzon Island
and that on the west and south coasts of Panay Island.
The first Grid system used in the Philippines was devised
by the USC&GS in 1919, which was also the first Grid used
in the United States. The “Grid System for Progressive
Maps in the United States” was the defining design for the
World Polyconic Grid (WPG), the predecessor of the Uni-
versal Transverse Mercator (UTM) Grid. During the 1930’s,
the Work Projects Administration for the City of New York
extended some of the specifications for the “Grid System for
Military Maps.” The first use of False Easting was introduced
to the American Grid System at the Central Meridian (
l
o
)
where False Easting = 1,000,000 U.S. Survey yards. May of
1943 marked the first use of the WPG by the U.S. Army Map
Service (AMS). The Philippines were based on a special local
meridian (122°) of that Grid as computed and tabulated by
the USC&GS. Although the WPG overprint color was purple
for most of the world, the color used for the Philippines was
black. The 1:200,000 maps had a 10,000-yard grid interval
and the WPG was used in the Philippines until 1952.
Other Grids found in the Philippines include the Nether-
lands East Indies (NEI) Equatorial Zone British Metric Blue
Grid based on the Lambert Conical Orthomorphic projection.
The NEI Equatorial Zone Black or Brown Grid in U.S. yards
is also found there (numerically the same Grid with differ-
ent units), but the occurrences for both are only on Cagay-
an Sulu Island and in the Sibutu Island group. These two
Grids commonly found in Malaysia and Indonesia flabber-
gasted me when I first encountered them some decades ago.
Besides Bukit Rimpah Datum being referenced to the Bes-
sel 1841 ellipsoid, the Scale Factor at the Latitude of Origin
(m
o
) = 0.997, False Easting = 900,000.000 m. (984,250.000
yd.), False Northing = 3,900,000.00 m. (4,265,083.333 yd.).
The Central Meridian (
l
o
) = 110°, and the Latitude of Origin
(Φ
o
) = 00° = the equator! I wasted my time trying to get these
parameters to work with Lambert Conformal Conic formu-
las until I realized that the Lambert Conformal Conic with
a Latitude of Origin at the equator decomposes to a Normal
Mercator! The NEI transformations worked fine after that.
Straight baselines are a method for a sovereign nation to
define its territorial waters by defining points along its coast
from which lines are drawn (on a Mercator projection). This
then establishes a line (ellipsoidal loxodrome or rhumb line)
from which that nation’s claim to territorial limits is mea-
sured. The straight baseline is a “new” development in inter-
national law. It had its inception in 1951 with the decision
in the
Anglo-Norwegian Fisheries
case in which the Interna-
tional Court of Justice upheld Norway’s method of delimit-
ing an exclusive fisheries zone by drawing straight baselines
along the Norwegian coast above the Arctic Circle, indepen-
dent of the low-water mark. This established a new system of
baselines from which the territorial sea could be measured,
provided certain geographic situations were satisfied. This
system with certain modifications was approved by the 1958
Geneva conference on the Law of the Sea.
On 17 June 1961, the Government of the Philippines ap-
proved Republic Act No. 3046, “An Act to Define the Base-
lines of the Territorial Sea of the Philippines.” The Philippine
government adopted the so-called “archipelago principle” in
drawing a series of 80 straight baselines about the external
group of islands. This baseline system in effect closed the im-
portant Surigao Strait, Sibuto Passage, Balabac Strait, and
Mindoro Strait, as well as the more internal passages through
the Philippine Islands. The largest body of water enclosed
was the Sulu Sea. Other significant seas enclosed include the
Moro, Mindanao, and Sibuyan. Furthermore, the Indonesian
island of Pulau Miangas and the Indonesian Straight Base-
lines were enclosed within the Philippine territorial sea! The
United States (and Indonesia) did not recognize this declara-
tion of territorial waters, which represents a thorny issue in
international boundary claims. Furthermore, to become rec-
ognized under international law, there must be an absence of
formal protests from other nations, and the territorial waters
declaration must be ratified by at least 22 other nations.
From 1947 to 1962, a national civil Grid was used on the
Luzon Datum of 1911 known as the Philippine Transverse
Mercator Grid with four zones. All four Gauss-Schreiber
zones had a False Easting at the Central Meridian of 500 km,
all four had a Scale Factor at Origin (m
o
) = 0.99995, and all
four had a False Northing Latitude of Origin of: (
f
FN
) = 04°
00´ 00˝ North. Zones II, III, and IV had Central Meridians (
l
o
)
= 121°, 123°, and 125°, respectively. For some reason unfath-
omable to me, Zone I had a Central Meridian (
l
o
) = 118° 20´
East of Greenwich. In a recent telephone conversation with
Mr. Joseph F. Dracup (retired Chief of Triangulation at US-
C&GS), he suggested that the weird Central Meridian might
have been designed to minimize the Grid scale factor some-
where in the Philippine Islands. On examination of a map of
the area, Palawan Island fits that criterion. Of course, the
military 1:50,000 mapping was based on the Gauss-Krüger
Transverse Mercator projection with the UTM Grid.
In 1962, a new national civil Grid was introduced for the
Luzon Datum of 1911, and it was changed to the Gauss-
Krüger Transverse Mercator projection. The previous Grid
Scale Factor at Origin and False Easting was retained, the
False Northing Latitude of Origin was changed to the equa-
tor, and the Central Meridians (
l
o
) = 117°, 119°, 121°, 123°,
and 125° for Zones I to V. A civilian edition of the 1:50,000
topographic series was produced in association with U.S.
agencies starting in 1961 and completed in the 1970’s. All
967 sheets have been published in color.
In 1987, the Philippine Bureau of Coast and Geodetic Sur-
vey was incorporated as a part of the National Mapping and
Resource Information Authority (NAMRIA). A total of 467 GPS
stations were observed which included 330 First Order sta-
tions, 101 Second Order stations, and 36 Third Order stations.
