plotter and a desktop computer such as the HP
9830.
The Itek Correlator EC-5 has special featu-
res, such as (1) adaptive scanning of pattern
shape and size to fit variation in detail and
contrast, (2) automatic gain control for varia-
tion in contrast, (3), different channel selection
(multiband video) for repetitive patterns, (4)
variable profiling speed or y velocity, and (5) a
failure routine. Early tests show that the pro-
duction rate is about 2.5 times the normal rate
and that the root-mean-square plotting error
ranges between 0.02 and 0.04 percent of H.
However, the rounding of peaks and valleys
due to the averaging of the scanning patterns
still exists. Experiments at IFAG (Lindig,
1974) indicated that final conclusions could
not be drawn then. It could only be said that
the correlator may not completely replace the
human operator although it can relieve him of
much of the routine work. Problems include
what is termed « floats », in which the z-carria-
ge moves up and down at full speed and loses
correlation, and the number of correlator failu-
res. Still open also is the question of whether it
is possible to increase the accuracy enough to
use the correlator for the production of con-
tours. The most recent work at IFAG implies
that technical improvements can reduce corre-
lation failures and that tests with nontopogra-
phic objects (e.g., oceanic waves and fine struc-
ture of road surfaces) showed favorable results.
In another system, developed at Hansa Luft-
bild (Krsll, 1974), coordinates and coded infor-
mation are directly transferred from the plot-
ter and digitizer as a « digital map » via inter-
faces to the disk of a minicomputer (PD8-8).
The programable computer allows for logical
checks and detection and correction of errors of
measurement and interpretation while the mo-
del is oriented. After intermediate storage of
the digitized data on magnetic tape, data are
processed interactively with a storage display.
Automated drawing tables can be used for the
production of maps.
Digital contours can be derived from profile
data by means of special programs. The Stutt-
gart program has already been described at the
1972 congress by Ackermann and Krauss. Ano-
ther program (Koch, 1973) is developed in con-
junction with the GEOMAP system mentioned
below, which is believed to be especially suita-
ble for topographic contours.
6
An interactive data bank and communica-
tion system called GEOMAP 80/1 is under de-
velopment- jointly by GEOMESS of Essen
(FRG) and Bunker Ramo (USA). It originally
operated on field data measured with the Zeiss
Regelta 14 Electronic Tacheometer and pro-
duced planimetry and contours. Recently, pho-
togrammetric data were also handled by the
system in a universal interactive manner (Heu-
pel, 1974).
Experimental work is also being carried out
at IFAG on digital planimetry models with the
objective of developing procedures and pro-
grams. An area of 5 km? has been restituted
from 1:14,000 photographs with the Planimat,
ECOMAT II, and magnetic tape storage and
producing digital data for the German base
map at 1:5.000. For automated topographic-car-
tographic work a newly developed instrument
by Contraves, Zurich, has been acquired by
IFAG.
For orthophoto production in FRG, the
three systems used are the Ortho-g Projector,
the Gigas-Zeiss Orthoprojector GZ-1 on-line
with a Planimat, and the GZ-1 with LG-1 sto-
rage unit for offline production (Hobbie,
1974).
FRANCE
Digital photogrammetry
Two recent articles by French authors (Du-
buisson, 1975 ; Vigneron, 1075a) discuss the
same general topic of automated photogram-
metric cartography and the development of a
cartographic data bank. The basic concept is to
use minicomputers on-line with (available) ste-
reoplotters, usually connecting several plotters
with one computer. The operations are divided
into two phases : (1) the upstream phase, which
includes data acquisition and digitizing, preli-
minary arrangement, and data checking and
preprocesing and (2) the downstream phase,
which includes data processing and integration
into a file control system and data bank. A
third article (Vigneron, 1975b) describes an
automatic third camera, which provides for
production of orthophotos off-line from either
digitized terrain profiles or digitized terrain
contours. The system includes a single plate-
holder, a teleprinter with punch-tape reader, a
magnetic tape, and an electronic interface.
