RESULTS of HYPERSPECTRAL ANALYSIS for the CHARACTERIZATION of MUDWALL. COMPARISON BASED on NORMALIZATION

Abstract

Currently, intervention in heritage is a task of social need. Non-destructive techniques are often used to carry out conservation and maintenance tasks. In the present. In this work we study the necessary calibration mode of a hyperspectral camera used in the characterization of the material to be conserved or to intervene. This camera is used to characterize the material according to its reflectance in different wavelengths. The result obtained is expressed as a function of the light condition at the time of the measurement. One of the most important phases of this technique is to normalize the values obtained in each take. This is conditioned by the intensity of light: the bigger it is, the bigger was reflectance value of a material at a given wavelength. This factor is corrected from patterns that are introduced in the scene. These patterns are elements whose reflectance values are known in the bands of the spectrum that the camera used registers. Likewise, they must reflect or absorb the maximum light (black and white reference, respectively) in order to delimit the maximum and minimum reflectance of each scene. These references will allow two scenes taken in different light conditions to be comparable. Therefore, the influence of black and white references on the scene is studied from the use of materials of different nature.