A method for fusion of perceptions is presented. It is based on probabilistic treatment of perception, where perception quantifies the chance an unbiased observer sees an environmental object, and the associated probability can be interpreted as degree of awareness for the object. The approach uniquely accounts for the fact that final realization or remembrance of a scene in the brain may be absent or elusive, so that it is subject to probabilistic considerations. For objects that are to be perceived from multiple viewpoints, such as a sculpture in a museum, or a building in its urban context, the probabilistic approach uniquely defines the fusion of perceptions. This is accomplished by carrying out the probabilistic union of events. The computation is presented together with its geometric implications, which become rather intricate for multiple observers, whereas the computation is straight forward. The method is exemplified for two applications in architectural design at different scales, namely interior and urban design, indicating the generic nature as well as the large application potential of the method.