In the last ten years, isovist analysis has emerged as a fundamental method for reflecting a person’s visual experience in cities and buildings. However, until now, most studies have used a two-dimensional planar perspective, neglecting the three-dimensional nature of vision. This paper presents a method to construct 3D isovists that give a more realistic account of a person’s visual experience in hilly urban scenarios where a person can see places that are not directly accessible. The paper aims to contribute to the construction of
objective methods to represent the environment in a more ecological way. The method was tested in the city of Valparaiso, a heritage city that spreads across thirty hills forming a natural amphitheater and whose charm comes largely from the visual experience that arises from observing distant parts of the city that are not directly accessible. The results show that three-dimensional isovists are capable of capturing the underlying visual properties of ravines and urban viewpoints in Valparaiso.