Evaluation of the visual quality of the selected samples

One of the functions required to the transparent systems is to make the user able to receive a series of information from the outdoor environment. Conventional clear glazings are very good to ensure this function. Glazing systems with obstruction, which might be inhomogeneous internal or external shading devices or obstruction embedded into the materials, as the case in exam, cannot properly guarantee such function. As an example, the outdoor vision is partially affected by the obstruction texture of the samples 12 and 13, see figure 5.

Sometimes, in contrast, hiding to sight a particular room or office is needed in order to ensure privacy or to reach an aesthetic purpose. In both cases it would be useful to give a parameter (or index) that is directly linked to the visual quality of the external enviroment.

Figure 5 Landscape observed through a window equipped with S12 and S13

No recognised standards exist at international levels, even if some research was carried out in the recent past. Next sub paragraph analyses the quality of vision issue, on the basis of the results obtained by the European project REVIS. Next an alternative approach, based on digital image analyses by cCd, is attempted. The results obtained with the two methods will be compared when the geometrical parameters for measurement in the second method will be defined using subjective tests.