Photogrammetric Information
Universal first-order analogue instruments which have been used to produce strip coordinates are
being replaced by non-universal first-order instruments producing model coordinates. Explicitely,
this means that the plotters without the base-alternating features (e.g., A8, ALO, PG3) are thus
promoted to the category of triangulation instruments.
A few stereocomparators are being used mostly by universities and by government agencies to measure
image coordinates. Computer programs then transform those image coordinates into model coordinates
for independent model triangulation. Monocomparators are used only to a very limited extent in
Canada.
Research and development work with the Analytical Plotter is continuing at the National Research Coun-
cil and at the University of New Brunswick in Fredericton.
Control and Auxiliary Information e é
The methods used in the establishment of new mapping control points are becoming very remote from
classical field surveying procedures. In the past few years, planimetric control was provided mostly
by Aerodist controlled photography and vertical control was obtained mostly from APR profiles.
New mapping control is now being planned with Doppler satellite positioning and Inertial Surveying
Systems, which provide the spatial coordinates of every point. Inertial navigational systems have
also been used in the aircraft to provide orientation information about the camera at the time of
film exposure (Masry and Vanicek, 1975). In the future, it is to be expected that a system such as
the ISS will be able to position the camera at the time of film exposure with sufficient accuracy for
its use in mapping applications. In this context, the adjustment program SPACE-M can use the pers-
pective centres as control points without any complications.
The use of APR profiles and Statoscope with PATM-43 has been studied extensively (Faig, 1975, Allan,
1975) but their full implementation in the 50 000 mapping programme is still under investigation.
The use of lake surfaces as levelling constraints in the adjustment is used whenever possible. The
main advantages are better stability in altimetry allowing a larger spacing between vertical control
points and a better screening of erroneous vertical points. The compilation of models from an adjust-
ment done with lake information is also facilitated by the fact that the problems with lake surfaces
are minimized. This situation is more obvious with SPACE-M than with PATM-43 the corresponding level-
ling constraints are stronger in SPACE-M. (Blais, 1976). € e
Digital Terrain Models
In the fall of 1976, the Surveys and Mapping Branch, will install the Gestalt Photo-Mapper GPM-2
system, which is a high speed and accurate data acquisition system for dizital terrain models. Pro-
gressive research by the Branch ( Allam, Wong, 1976) has been conducted for the development of a com-
puter system for the gridding of topographical surfaces and the interpolation of Contour lines.
Similar research is conducted at the University of Guelph by S. Collins and at the University of
Waterloo by J. Lindels.
PUBLISHED WORKS
Allam, M.M. (1973): Statistical Methods for Analysis of Aerial Triangulation Errors, Revista Carto-
graphica, No. 24 - 25, Mexico pp. 27 - 46.
Allam, M.M. (1973): A Program for Analytical Aerial Triangulation, Canadian Surveyor. Vol 27, No. 4
December 1973, pp 301 - 307.
,
Allam, M.M,. (1975): Mathematical Statistical Methods for the Analysis of Aerial Triangulation Adjust-
ment Errors Using a Computer Program, Canadian Surveyor, Vol. 29, No. 2, June
1975. pp.175 - 188.
Allam, M.M. (1976): Photogrammetric Deformation of Lake Surfaces Caused by Air Temperature piterentiarll -
Over Water Bodies, ISP' Commission III, Helsinki.
