291 
Ls done, 
rectification, to a generalized Helmerth transformation, to an analogical 
differential rectification, i.e. to a correlation by means of the correla- 
tional-dispersional analysis. For all these methods we have very good 
3vious 
3S. 
computer programs and techniques, practically tested. Within the differ 
ential methods we may include the MSS recordings processing as well as the 
solving of the precision correction problem of the ERTS data if we obtain 
e the 
or elaborate the automatic computer programs. 
storage 
Referring to the items proposed above within the approach of 
this problem it is to be mentioned that: 
ata to a 
For the precision association of the data from two or more 
different missions of data storage the computer technique and program from 
the analytical processing of the triplets may be used when dealing with 
photographical images. For this, there are well drawn computer programs. 
ical 
great 
The transposition of a preestablished points grid on a photographical image 
may be obtained on a homologous image, even if between them are differences 
of scale, emulsion, etc. In Fig. 1 the principle is presented. The points 
may be read on a stereocomparator (or a zoom-stereocomparator) in the case 
g of the 
of large scale differences between the two images, or to an interpretoscope 
to which it is adapted a measuring system with a reference grid spaced at 
5-10 mm. 
owing 
In order to adjust the geometrical qualities of the recording 
data to a basic mapping material of reference, we used a polynomial trans- 
;ible, 
:rical 
r years 
formation of a rigorous type/Appendix 1/; the advantage of this procedure 
is that the contour lines with equal error may be traced and they may be 
certainly used as corrections; the computer-program allows by interpolation 
the error-corrections to be established for each point using a digital model 
of surfaces representation. A suggestive example is given in Fig. 2. 
ilogical 
strictly 
For the transportation of the data in successive steps (survol 
system) from the smallest to the biggest scales and vice versa, one may use 
the combined procedure which is referring not only to the geometrical but 
5SSing 
Dsed by 
also to the spectroradiometrical aspect. 
In fact the above positional registering of images can be 
considered as a preprocess. 
tain the 
e different 
erentially. 
on is re- 
The preprocessings have the aim of establishing the atmospherical 
effects on the photographs-recordings, i.e. homogenization-calibration from 
this point of view. 
A simple method of estimating the atmospherical effects in bulk 
on the distortion of image contrast is based, as one knows from a long 
practice, on a graphical solution using density image measurements of some 
field reference areas whose spectral reflectances are known, even as 
relative values if not absolute ones. The obtained density data are 
en simul- 
lements. 
real 
normalized at the sensitometrical response curves of the film in a way which 
compensate for the variations of the response curve form due to the laboratory 
processings, to the filter factors, to the exposure, atmospherical radiance