Method for building a seismic imaging velocity model, particularly at the boundary of a geo-body, and to perform imaging, by taking into account the elastic reflection and scattering information in the seismic data. More illumination of the base and flanks (or in general, the boundary) of the geo-body is provided from (a) inside of the geo-body (502), with elastically converted waves at the geo-body boundary used (via elastic RTM flooding); and (b) from outside the geo-body (503), by utilizing prism waves with elastic RTM to handle the phase correctly in the model building step. The increased illumination and correct elastic phase are used for geo-body boundary determination. Elastic RTM is then applied (505), along with the elastically derived imaging velocity model, to maximize the use of elastic energy in the imaging step, and to obtain the correct image with the correct phase.