The localization of weak properties or bad behavior of a structure is still a challenge for Non Destructive Testing (NDT) tools development and Structural Health Monitoring (SHM) design. In case of random loading or material properties, this challenge is arduous because of the limited number of measures and the quasi-infinite potential positions of local failures. Deterministic algorithms and specific multi-sensors systems are developed to this aim. In that case, generally, the precision of the positioning of a defect goes with a lack of sizing. However, the stochastic field is rarely a pure white noise and has a stochastic structure and probabilistic properties. These properties should be used to provide rational aid tools for optimizing the number of sensor. The paper shows that the stationary property is sufficient to find the minimum quantity of sensors and their position. A measure of the quality of information is suggested and the illustration is performed on a one-dimensional Gaussian stochastic field.