Spatial OLAP refers to the integration of spatial data in multidimensional applications at physical, logical and conceptual levels. The multidimensional aggregation of geographic objects (geographic measures) exhibits theoretical and implementation problems. In this paper, we present a panorama of aggregation issues in multidimensional, geostatistic, GIS and Spatial OLAP models. Then, we illustrate how overlapping geometries and dependency of spatial and alphanumeric aggregation are necessary for correctly aggregating geographic measures. Consequently, we present an extension of the logical multidimensional model GeoCube (Bimonte et al., 2006) to deal with these issues.