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Title
Remote sensing for resources development and environmental management
Author
Damen, M. C. J.

50
Symp
would of course need a much denser field of control Trorey, L.G. 1947.
points than 1 per 85 photos. In fact, each Slotted templet error.
individual aerial photograph would need control. Photogrammetric Engineering, vol. 13, no 2,
This independent control per photo is provided by p. 227-229
the Landsat map control method in a more elegant
way.
New
by us
5.2 Evaluation
The Landsat control method seems ideally suited to
mapping situations in remote areas where only
unreliable maps exist, and with aerial photographs
which have been flown with tilts and altitude
variation beyond normal margins. Usually, these
three conditions are encountered simultaneously.
In remote regions of the Amazon basin, for instance,
reliable maps are hard to find and aerial photography
coverage by local air survey companies is not
exactly awe inspiring as far as quality is concerned.
In such conditions it is going to be nearly impossible
to employ the slotted templet method.
In a mapping situation with ample ground control
the slotted templet method would, as far as accuracy
is concerned, win from the Landsat airphoto map
control method. However, this situation is
hypothetical because ample ground control implies
that the mapping exercise must be taking place in
the developed world where sophisticated
aerotriangulation techniques have taken over.
Therefore, the method of airphoto mapping using
slotted templets has survived up to the present
only in remote areas. Even here, the slotted
temple method will have to give way to another
approach. This could be with Landsat controlled
airphoto mapping, because it has a number of
advantages over the slotted templet method,
especially with airphotos that were flown at
varying altitudes and with tilt. These advantages
are the following:
* photo tilt and scale variations do not influence
accuracy of the map;
* no ground control is required prior to flying;
* Landsat control is always densely and evenly
distributed over the map which implies that
acceptable accuracy also is evenly distributed;
* map compilation is done very swiftly even under
field conditions.
We can therefore conclude that the slotted
templet method has become obsolete, not only in
the industrialized world but also in mapping
situations at the 'last frontiers'. Especially in
the latter regions the airphoto map control method
using Landsat is the preferred alternative as it
is the most cost-effective mapping routine for the
production of basemaps with an mean accuracy
requirement of 30 m, and as it can always be used
in conjunction with topographical traversing work
to correliate field data with airphotos and to
update basemap accuracy.
REFERENCES
Dovey, S. 1983.
Improved framing accuracy with Landsat-4, ALS
Newsletter, vol 3, no. 1, p. 5-6.
Dovey, S. 1986.
Personal communication.
Slama, C.C., H. Ebner and L. Fritz. 1980.
Aerotriangulation, in:
Manual of photogrammetry (ed. C.C. Slama),
p. 453-456.
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