UTILIZATION OF CONSTRAINTS INCONTROL DENSIFICATION 
Robert Burtch 
Center for Photogrammetric Training 
Ferris State College 
Big Rapids, Michigan 49307 U.S.A. 
Comission TII 
ABSTRACT 
The major | costs incurred in control  densification by 
photogrammetric techniques is the surveying af the initial 
control. This could be reduced if existing. control. was 
available. In many localities, there is a wealth of cadastral 
survey. information that, could be used in a photogrammetric 
adiustment.through .constraints. | Thiís information is often in 
the form. of distances, angles, and/or azimuths/bearings.. The 
net result should be a reduction of new terrestrial surveying 
for the photogrammetric process while maintaining the desired 
accuracy: of the densification "for cadastral purposes since 
local scale and orientation become a part of the adjustment. 
BACKGROUND 
The. United States is thought of as one of the leading developed 
countries in the world. Despite this, glaring inadequacies 
dealing with knowledge - of the land are becoming more apparent 
every day. “This: has led for a. call for the development of à 
multipurpose land information system. The foundation of this 
system must. bea cadastre built upon : 2.dense network of 
geodetic control [Panel on a Multipurpose Cadastre, 1983]. 
Vet, out of the over three thousand counties in the U.S., only 
a ‘few have in place a -sufficiently-.dense.geodetic control 
network that would’ support a multipurpose:.cadastre. in fact. 
if'one-looks at the 500-leading counties in terms. of economic 
activity, we: find that “only 10% have a. geodatic network of 
sufficient density “from which densification for support Of a 
cadastre could commence [Barr, 1933]. 
Many methods for densification of control are now available and 
they offer significant Savings over conventional terrestrial 
surveying techniques. These include Doppler surveying, GPS 
Satellite surveying (i.e., -satellite interferomelric systems), 
inertíal surveying systems, airborne laser ranging systems, and 
amalytical photogrammetry. These-can-al]--be- used. in some form 
to provide geodetic control necessary to support a multipurpose 
cadastre. The cost of this controi-does not come: 1igntiy. 
Barr [1993] “points out that? 40-70% of the! costs In: the 
development of à cadastre (survey control, base - mapping, and 
cadastral surveys and maps) are attributed to survey control. 
These costs fluctuate because of area and the method of control 
densification utilized. 
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