In addition to the soil 
disturbance depicted by Figure 
10, other features which could 
benefit from the effect would 
be rock outcrops, stressed 
vegetation, and terrain as 
rendered in urban areas. 
Possibly the most advantageous 
feature of the negative type 
2443 product is in its use as a 
conventional negative product 
in electronic dodging contact 
printers. Autododge can be 
controlled, hence more uniform 
printing can be achieved, 
consequently products such as 
mosaics can be produced with 
better tonal uniformity. 
In small scale applications the 
2443 emulsion (positive or 
negative) is definitely the 
choice film if color is 
required. Its infrared 
sensitivity will provide the 
haze penetration which is often 
required at higher altitudes. 
As a final note on graininess 
and sharpness of the imagery, 
it does not seem that it is 
significantly affected by the 
negative process (Figure 11), 
although a more quantitative 
analysis is needed to 
substantiate this observation. 
IMAGE ACQUISITION TECHNIQUES 
Innovation in acquiring aerial 
photographic imagery has 
concentrated in two areas: 
image contrast control and 
image motion compensation. 
Contrast control awareness in 
Canada has evolved primarily as 
a response to federal 
requirements on aerial 
photography, while image motion 
compensation has been a 
technological implementation of 
major aerial camera 
manufacturers. 
Image Contrast Control 
Contrast control has been 
widely used as a tool in 
photography almost since its 
inception; the popularization 
of the Zone System [28] is an 
attestation to this. In aerial 
photography the operational 
concept of controlling contrast 
is a relatively recent event. 
Two reasons account for this 
situation: one, older versions 
of photographic specifications 
required constant processing 
(analogous to no contrast 
control), two, methods to 
determine terrain brightness 
range were either nonexistent 
or experimental [29]. The 
revision of the 
Interdepartmental Committee on 
Aerial Surveys specifications, 
specifically item #27, imply 
that the air photo firm utilize 
techniques to control the film 
contrast in order to achieve 
the aim density range of 1. 0 
[5]. The modification of 
exposure through obtaining film 
speeds associated with varying 
average gradients and the 
processing of film to the 
different average gradients is 
now generally recognized [30- 
32]. Users have seen these 
techniques translated into 
better overall tonal ranges, 
more consistent detailed 
information in shadow areas, 
and better overall quality in 
aerial photography product. The 
problem of determining terrain 
brightness range, 
unfortunately, is still 
generally a subjective 
evaluation and is likely the 
reason not all aerial firms 
follow the ICAS exposure 
processing guidelines. Although 
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