  With the increasing demand for mobile robots and autonomous vehicles, several
approaches for long-term robot navigation have been proposed. Among these
techniques, ground segmentation and traversability estimation play important
roles in perception and path planning, respectively. Even though these two
techniques appear similar, their objectives are different. Ground segmentation
divides data into ground and non-ground elements; thus, it is used as a
preprocessing stage to extract objects of interest by rejecting ground points.
In contrast, traversability estimation identifies and comprehends areas in
which robots can move safely. Nevertheless, some researchers use these terms
without clear distinction, leading to misunderstanding the two concepts.
Therefore, in this study, we survey related literature and clearly distinguish
ground and traversable regions considering four aspects: a) maneuverability of
robot platforms, b) position of a robot in the surroundings, c) subset relation
of negative obstacles, and d) subset relation of deformable objects.
