In order to describe droplet spatial distribution in a spray, a numerical study is carried out to firstly, analyse theoretically distributions which could be used to model droplet spatial distribution and secondly, to investigate the influence of acquisition parameters of the optical Mie scattering measurement technique on the experimental characterization of droplet spatial distribution. To this end, the first four moments of the probability density function are compared for the randomly uniformly distribution, the inhomogeneous Poisson distribution and the preferential segregation distribution. Furthermore, a parametric study based on laser sheet thickness and image resolution is performed to determine their influence on droplet spatial distribution. Results show that the first four moments of the inhomogeneous Poisson and the preferential segregation distributions deviate from their theoretical values based on randomly uniformly distribution. Moreover, it is shown that the acquisition and the processing of Mie scattering images acquired from a spray in a three dimensional flow leads to bias on the probability density function and the characterization of the droplet spatial distribution.