Spectro-Photo-Interferometry of Stellar Pulsation (SPIPS) - A more precise and more accurate implementation of the parallax of pulsation method

We present our implementation of the parallax of pulsation method which integrates all observables and physical modelling of the photosphere to get the best statistical precision and controlled biases. This method has been validated on well known stars and used to estimate observationally the projection factor of the HST -FGS sample. Our future developments include application to the Gaia Cepheids and modelling of the spectrum.