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4.3 Decreasing the problems of vegetation for the large scale 
measurements by combining terrestrial and photogrammetric 
One of the greatest problem of the application of photogram- 
metry to the final stage of Highway Design concerns the influen- 
ce of the vegetation, which in many cases makes the use of air- 
photographs impossible. The development of new equipments for a 
combined measurement for measuring angles and distances and with 
automation of the registration of the data, will open new possi- 
bilities of combining photogrammetry and terrestrial measure- 
ments effectively. 
This is important when it is a question of large scale numeri- 
cal and graphical topographical information in the final design 
stage. Developing a system similar to the semi-automated system 
presented by Mac Leod in (19), but where the possibilities of 
complementary addition of terrestrial data, would thus mean an 
important step forward for the photogrammetric application. 
4.4 Ortho-photomaps 
The technical problems around the production of orthophotos 
can be regarded as solved though several new equipments still 
are presented on the market. The problem of the application of 
orthophotos to the different stages of Highway Design, there- 
fore, concerns the difficulties of convincing the Highway de- 
signer on the advantages of the use of orthophoto instead of a 
plotted map. The questions of photo-identification and photoin- 
terpretation concerning the topography have been taken care of 
by the stereooperator in the latter case, but are to be solved 
by the engineer when using an orthophotomap. It may also be- 
come easier to present the design features on a drawn map com- 
pared to on an orthophoto. The use of a plotted map can also 
be combined with a simultaneous interpretation study of reprints, 
stereoscopically, of the photographs. 
Dr W Blaschke has in his invited paper to the Ottawa congress 
(9) presented an interesting contribution to the application 
of orthophotomaps to the different stages of Highway Design in- 
cluding also some practical examples. 
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