If the photos are acquired in normal case, the co-linearity
equations (2) can be simplified and control points are not
necessary for the restitution purpose. An alternative
photogrammetric method provides for the application of a scale
factor to the model by means of the introduction of direct object
distances measurements.
This opportunity consents the execution of surveys in economy,
employing no metric cameras, that have to be calibrate at the
moment of the survey, without the requirement of expensive
Total Stations and, in particular, consents errors acceptable for
architecture survey, in archaeological fields and in general
appear the ideal method for the documentation of the Cultural
Heritage.
These alternative photogrammetric methods enlarge the use of
photogrammetry even to person without culture of the geomatic
disciplines; nevertheless empirical verifications concerning the
real accuracy of the elaboration realized are still necessary to
better understand the effective performance of the systems.