The analysis was carried out by every author separately,
on an approximate scale of 1:230,000, and the first author
investigated also the broader area on scale 1:1,000,000.
The final sketch included only fractures and ring structures
Shown in all these representetations. This mode was chosen
in order to investigate personal influence, scale. and
image quality in the interpretation. The following conclusions
have been drawn:
Subjective factor. Same as any other analysis (field,
photogeologic, office), the analysis of space imagery is not
deprived of subjectivity. Several sources of subjectivity
have been noticed in this study:
- Fractures are often marked by discontinuous traces in the
relief, and every author -depending on his training, image
quality and scale- makes his own choice in linking them,
showing them as short individual fractures, or adopting
various possible relations in domains of branching.
- A scanogram normally shows a very wide number of fractures;
the choice of the ones to be presented or neglected bears
necessarily the elements of subjective decision.
- Training of the interpreter controls his capability of
discerning fractures not clearly sculptured in the relief
(the scanogram has been analysed also by two young
interpreters, trained in photogeology but unexperienced;
their interpretations differed significantly from each other
and from the interpretation by the present authors).
The scale controls dimensions of perceptible fractures,
which is well known in photogeology. Large scale imagery
(about 1:230,000) is suitable for discovering fractures
of even km-dimensions; large (Hkm) fractures are not readily
seen on this scale. Small scale imagery (1:1,000,000)
makes possible discovering the large, Hkm-fractures, even
when poorly expressed in relief.