extrusion based on a map

Hi I'm making this brick facade that is supossed to be like a wave surface combined with randonly extruded brick (see attachemnt) at this momment it is a modelled cluster of 10x10 brick, instanced, rotated and copied around. But no flexibility - I would like to be able to locally control the amount of extrusion parametrically or by a density map. I don't think displacement is the optimal way to do this. Does anyone know if there is script that would help me?

Cheers

Matej