We investigated the structure of 37 spatial dimensions of opposite properties, such as open-closed, vertical-horizontal, full-empty, and far-near. The structure of each dimension was defined by means of phenomenological psychophysics. Metrical and topological definitions of the three components of the dimensions (the two poles and the intermediate states) were derived and similarities and differences between these dimensions were identified. These studies revealed that the proportional extension of the two poles and the intermediates can be defined by participants with high accuracy. These metrical definitions are further enriched if topological aspects identifying the nature of poles and intermediates are considered, i.e. if a distinction is made either between points and ranges or between open and closed ranges. Four types of opposites emerged as a result of these analyses: (i) closed range, point, closed range (cpc), e.g. left-right; (ii) point, range, point (prp), e.g. full-empty; (iii) open range, none, point (onp), e.g. open-closed; (iv) open range, range, closed range (orc), e.g. high-low. We believe that this approach may be extended to the study of the perceptual structure of opposites in any domain. Further research would reveal whether the four structures which emerged from the studies on spatial opposites are typical only of spatial dimensions or may have a more general application in various perceptual domains. We suggest that this type of investigation is a fruitful addition to both semantic and linguistic approaches to opposition.