In this work, we present a collection of different techniques oriented to the altitude estimation in topological visual navigation tasks. All the methods use descriptors based on the global appearance of the scenes. The techniques are tested using our own experimental database, which is composed of a set of omnidirectional images captured in real lightning conditions including several locations and altitudes. We use different representations of the visual information, including the panoramic and orthographic views, and the projection of the omnidirectional image into the uni sphere. The experimental results demonstrate the effectiveness of some of the techniques.