In this paper we present the results of a study comparing the performance of various centroiding methods on an extended spot. Various spot shapes, in good agreement with measurements of the Sodium layer density profile are investigated. We compare the performance of center-of-gravity (COG) based ad cross-correlation (CC) based methods and the matched filter (MF) algorithm. While their performance are comparable in the case of a Gaussian Sodium profile, we show that, above 15 to 20m off-axis, substantial differences appear in the case of a known non-Gaussian Sodium density profile. CC based and MF methods seem to have comparable or better performance with various spot shapes while non-Gaussian shapes have dramatic impact on COG based methods.