it if due con-
the second is
rrespondence
‘pass’ points
| for 1/50000
ey Establish-
rrived at by
eter readings
rocedure has
10ds, perhaps
and greater
e air camera
t subject, an
traverse and
an be photo-
hen demands
as carried on
rs and B. W.
re study, and
> use of the
r the cameras,
is resulted in
1 experienced
to 100 miles
estimated at
sq. km) over
0,000 sq. km)
m radial alti-
| country like
ble, the value
re applied to
| followed the
ry Branch, of
the beginning
(15)
In 1929 methods were devised for the satisfactory measurement of tree
heights from vertical air photographs (Ref. 23). Other investigations for
identifying species and classification and in the development of mapping methods
for purely forestry applications have been carried on with success (Ref. 24).
The Seelyscope, as originally devised for the transfer of forest types from photo-
graph to map (Ref. 25) has recently come into more extensive use because of
its application to linear detail of all kinds.
NON-GOVERNMENTAL MAPPING
While most of the early developments of photogrammetry in Canada took
place in the central government offices at Ottawa, a certain amount occurred
elsewhere. As the subject is becoming of greater economic importance this
proportion is increasing. The Province of British Columbia has been outstand-
ing in the amount of investigational work carried on, and amongst this may be
mentioned the use of small size air cameras by Andrews (Ref. 26).
Commercial organizations, notably the large paper companies, have deve-
loped methods for application to forestry purposes, but few published data are
available. Latterly there have been more activities on the part of air mapping
companies, using, e.g., the radar altimeter, but little is known of the results.
In the universities, it is to be regretted that, in general, very little attention
has been devoted to photogrammetry, despite its great importance to Canada.
A noteworthy exception is the University of Toronto where for several years
Professor K. B. Jackson has been conducting a special course on the subject.
ACKNOWLEDGEMENTS
The information in this history has been obtained mainly through personal
contact with men actively engaged in the development of photogrammetry in
Canada — some of them since its very beginning. Special mention for assistance
in supplying material is due to R. B. McKay, P.E. Palmer, W. H. Miller, R. D.
Davidson, J. E. R. Ross, B. W. Waugh, W/C H. Pearce, and Maj. J.I. Thompson.
R.H.F.