n Alas - Alaska Division of Geological & Geophysical Surveys - State ...

were deslgned to impMve the accuracy and encourage
the use of latitude and longitude for recording geo-
graphic posltlons in the field and office, where expen-
sive computer facilities might not be readily
available. Use of a computer to generate templates
serves as a method of extending the precleion and
flexibility of computer facilities to work areas where
only less wphlsticated facilities are available.
The Survey's use of template for determining
geographic coordinates was started in 1974, when 4s-
tematic aollection of' geochemlcd md geophysical
data was accelerating in the Alaskan Mineral Resource
Assessment Rogram (AMRAP). They were, however,
ao outgrowth of older techniques that had developed
during the previous 25 years for determining the geo-
graphic coordinates required for early files of gravity
data used in U.S. GeoIogicaI Survey computers. Such
geographic coordinates were generally measured by
interpolating from linear scales and using multlplica-
tion factors for scale conversion. Later, adjustable
lo-point dividers and elastic scales were commonly
used. To calculate gravity anomalies in the fleld, D.
P. Barnes began using handdrawn latitude templates
covering 5- by 10-minute areas on all Altlskan
I: 63,360-scale maps, and for detailed surveys these
were supplemented by hand-drawn longitude templates
coverin the full height of a few maps. Meanwhile,
Plodf Ress) naa written computer programs to plot
station locations on UTM and polyconic projections and
to verify these locations before kther data process
ing. Many of these plots revealed lwatlon-
measurement errors, and the advantages of the geo-
graphic over the artesian system sometimes seemed
less important than the errors made in measurements
involving scales and conversion factors. After dls-
cussions of mutual needs and problems, Plouff wrote a
computer program to produce tempbates that comblned
the features of D. F. Barnes' handdrawn indlvldual
latitude and longitude templates. Flexbility was pro-
vided In the computer program for drawing templates
at any latitude, any map scale, on either of two map
projections, and at any multiple of 1 second for fine
interpolation. Discussions with Henry C. Berg end
other geologists assisted in improving format, line
spacing, and labeling to standardize the three principal
template types now used with Alaskan topographic
maps. The primipal tdpographle-map scales in Alaska
are 1:250,000, or 4 miles to the inch (covering a 1-
degree latitude rage aild either 2 or 3 square
degrees), and 1:63,360, a? 1 m1le to the inch (ooverlng a
ltminute Latitude range with widths varying from 20
to 36 minutes), Standard templates cover the full
notth-South dirnenSim of each map, and 30 minutes of
longitudind wfdth of the 1:250,00O*aie maps and 10
minutes longitadinal width of the 1:65,380-scale maps
so that each template is about 10 by 45 cm. The
1:250,0OOsc11le templates have lines every minute of
longitude and every halt-minute of latitude, and every
fifth Line is usually drawn thicker and Labeled. There
are two categories of 1:63,360-scde templates: One
wlth each minute divided into units representing
seconds, ami the other with each minute divided into
decimal parts. Templates with divisions In seconds
have Unes every 10 seconds (each minute divided into
slx parts), and the lines at every minute are thioker
and labeled. Templates wIth minutes divided declmal-
ly have llnes every 0.1 minute of latitude and every 0.5
minute of longitude, and the Lines at every minute or
half-minute are thicker and labeled. The separate sets
of templates, one with minutes divided into seconds
and the other into decimal parts, were prepared be-
cause both these systems of recording locations are in
common use. Templates In decimal pats of degrees or ,
other scales (some new Alaskan maps are now being
published at scales of 1:25,000 and 1:50,000) can be
easily prepared if (when) needed in the future.
The templates were origlndly plotted on paper
on a drum plotter and were photographically duplica-
ted as contact prints on either positive olear fflm or
negative fiim. Attempts to plot directly on Mylar
have been only partly succsssful, mainly because of
pen-an&M problems. Ihe hlgh cost of photographic
reproduction initially Umlted widespread template dis-
tributlon. However, a set of negatives for template
reproduction has recently been sent to the National
Cartographic Information Center, U.S. Geoioglcal Sur-
vey, 218 IS. Street, Anchorage, AK 99501. Upon re-
quest, the Center can arrange for the dbtrlbution of
clear-fllm copies of the templates to the public in
ALaska. In addition, a copy of the computer program
was transmitted to Denver, where It w e used to
produce a set of smaller templates (Campbell and Van
Trump, 19828, b) covering half the latitude range of
each tler of standard quadrangle maps. Copies of
these templates are reproduced on xerographic film
for distribution through the Open-Plle Services
Section, Western Distribution Branch, U.S. Deological
Survey, Box 25425, Federal Center, Denver, CO 80355.
REFERENCES CM%D
Campbell, W. L., and Van'bump, George, Jr., 1982a,
Catalog of avaLZable clear mylar templates used
to determine latitude and longitude of sample
localltles between the latitudes of 51°00'~0" and
71°30'~0n at the geale of 1:63#60, and between
the latitude of 49 00'0OM and Ti 30'00" N. or S. at
the scale of 1:250,000: U.S. Geological Survey
Open-File Report 82-723, 4 p.
-1982b, Clear mylar templates used to measure latitude
and longitude of sample locaiities at scales
1163,380, and 1:250,000 between the latitudes of
40~00~00~ and 71°~0t~~" N. or S.: U.S. Geological
Survey Open-File Report 82-724,214 p.
Plodf, Donald, 1968, Determination of rectangular
coordinates for map projection~odlfieation of
basic form- and appUcatIon to computer plottlngs,
& Geological Survey researah 19681 U.S.
Geological Survey Professional Paper 600-C, p.
C174-C176.
The U S S,oglcd Survey Public InqdAes Office in
hhorage
The Public Inquiries Office (PI01 In downtown
Anchorage (Skyline Building, 218 "En 'Street) Is part of
a network of 10 such U.S. Geological Survey PI0
facilities throughout the country. These ofP1ce.s serve