Experimental research on several types of analytical 
bridging: statistical analysis of model errors 
Dott. Giovanna Togliatti 
Istituto di Geodesia, Topografìa e Fotogrammetria 
e Centro di Addestramento e Studi Fotogrammetrici del Politecnico di Milano 
(Paper for the X International Photogrammetry Congress, Lisbon, 1964) 
Summary. — The experimental results are given relative to the bridging of five strips, whose 
plate coordinates have been measured twice on a stereocomparator O.M.I. TA 3. The bridgings differ 
for the number of points that have been used for relative orientation and scale transfer. 
The results are analysed from three different view points in order to find : 1) which bridging 
method leaves the smallest residual parallaxes in each model and the smallest deviations between 
models ; 2) whether some systematic errors in relative orientation are present, due to local deforma 
tion of the plates ; 3) whether some systematic errors in model formation are present, due to asymme 
tries caused by the objective lens. 
i. — During the last year, the « Centro di Addestramento e Studi Fotogramme 
trici » of the Politecnico of Milano collected and studied a considerable number of 
results on the intrinsic accuracy of the bridgings of photograms. As known, one of 
the centres participating in the work of the O. E. E. P. E. Commission B, concerning 
the study of blokes, is the centre of Milan, where an extensive program of measu 
rements and computations has been laid down, contemporarily to the study of 
the blocks. 
This work gave material enough for a statistical inquiry concerning the beha 
viour of the residual parallaxes on the model and of the connection of the succes 
sive models, analysed from different points of view. 
The material for study consists of 5 strips, covering, on the whole, an area of 
about 6x6 km i. 2 . The camera used is a Wild RC7, with plates 10 x 10, focal 
length 100,5 mm- The relative flight altitude is about 1 200 m : therefore, the ave 
rage scale of the plates is 1 : 12 000. On the surface covered by this block, about 
200 known points have been placed, in order to study the accuracy obtained with 
the strip bridgings and with the adjustment of the block. However, the analysis 
of the absolute results, namely the discrepancies between the computed coordinates 
and the ground known points, is beyond the aims of the present investigation that, 
on the contrary, concerns the following subjects.