Schut, G.H. (1973): Similary Transformation and Least Squares, Photogrammetric Engineering, Vol. 39, 
No. 6, pp 621 — 638. 
Schut, G.H. (1974): Two Interpolation Methods, Photogrammetric Engineering Vol; 50, No. 12, pp 1447 - 
1453. 
Young, M.E.H. (1973): 1:50 000 Mapping in Canada, 34th Photogrammetric Week, Shuttgart. | 
Zarzycki, J.M. (1972): The Use of Auxiliary Data in Aerial Triangulation, International Archives | 
of Photogrammetry. ; 
COMMISSION IV 
Mapping from Photographs 
Reporter: Dr. J,M. Zarzycki, Surveys and Mapping Branch, E.M.R. € e 
In Canada, the period of 1972 to 1976 has been an exciting time in the development of automated sys- 
tems for photogrammetry and cartography. The Surveys and Mapping Branch of the Federal Department 
of Energy, Mines and Resources; General Survey System Division of Statistics Canada; Lands Directo- 
rate of Environment Canada; several survey departments in provincial and municipal organizations; 
are all heading towards automated systems in surveys and mapping. 
Under the direction of Dr. J.M. Zarzycki, the Topographical Survey Directorate, Surveys and Mapping 
Branch, E.M.R., has developed an interactive digital map compilation system and will employ the 
Gestalt Photo Mapper (GPM-2) for the production of digital terrain models and orthophotos. 
The interactive digital compilation system (DIGICOM) has the potential to cut the time needed to 
produce digital data for mapping by 20 to 50 percent. The focal point of the system is the digiti- 
zing and edit stations that are capable of both entering and editing the digitized data in real time. 
The data is entered from the stereo-instrument to the mass storage of the system via a computer link. 
The DIGICOM program is aimed at digitizing the map information, not from a completed map, but directly 
from a stereo photogrammetric model, which is an early stage in the map compilation process. 
The technical staff at Gestalt International Ltd (formerly known as Hobrough Limited) developed the 
Gestalt Photo Mapper GPM-I in February 1972; it produces fairly accurate orthophotos for an increased 
range of scales and slopes. In 1975, the Gestalt Photo Mapper II was developed with improvement in 
precision and speed in the production of orthophoto and digital terrain models with less restriction 
on scale and slope and, more important, by increased contouring accuracy. In the GPM-2 the stereo © 
model is viewed on high-precision television circuits. Each photograph is scanned by a simple high e 
precision open loop electro-mechanical scanner. Flight-line irregularities, corrections for earth 
curvature and camera lens distortions are removed by controlled distortion of the TV master scanning 
pattern. The overlapping area of the photographs is divided into patches. Video representation of 
the two patches are sent to the correlator, where the analog signals are converted to digital signals 
before being further processed. Parallax due to differences in height in each pair is represented 
by phase shifts in the two video signals. The correlator analyses the differences for each pair, cal- 
culates the height, and alters the scanning pattern to remove the parallax expected for the calculated 
height. With this height data it is possible to record the orthographic projection as well as the ele- 
vation contours automatically. By systematically transforming the model patch by patch, a complete 
map projection and contour sheet of overlap area can be photographically recorded at photo scale.: 
Simultaneously with the production of both photographic records, a digital terrain model can be 
recorded on magnetic tape. S 
The data bank in the Surveys and Mapping Branch is organized by 1:50 000 map sheets, and thus the 
National Topographic System (NTS) is the index to the data bank. The data is kept in XY coordinates 
while the connection from the XY coordinates to the national geodetic coordinate reference system \ 
of latitude and longitude and UTM coordinates is established by identifying the S-W corner of each 
map sheet in both coordinate systems. 
Under the direction of Mr, W. Switzer, Environment Canada is developing the Canada Geographic Infor- 
mation system with the objective of presenting data in a form required for land-use planning at the 
local, regional, provincial and national level; and, to design a system which will collect and store e - 
data from maps and statistical tables in a form that can be analyzed quickly. In 1976, 83 percent 
10