Landscape heritage, especially if it does not arouse great public echoes, needs great attention, starting from knowledge and metric documentation processes to which reality-based sensing techniques often contribute significantly. The primary purpose of this work is to reflect on the possibility of identifying submerged built heritages, which are sometimes characterised by precarious safety conditions due to abandonment, through multispectral photogrammetric technologies with primary data acquired by UAVs. The experience carried out in an impervious alpine territory foresees the close relationship of integration of photogrammetric techniques in the visible and the multispectral ranges, with the integration of terrestrial scanning solutions from slam-based mobile systems, to validate the results provided by the analysis of the spectral signatures of different kind of soils.