Retopology - Blender Master Class: A Hands-on Guide to Modeling, Sculpting, Materials, and Rendering - page 105

Figure 7-17: Retopologizing the legs. For some areas, I had to either clean
up the retopologized mesh manually or simply model new areas, such as the
underside of the legs, from scratch. Some extra embellishments, like rivets and
so on, I placed by hand.
Figure 7-16: Retopologizing the abdomen. The
part in the middle was separated from the main
body of the abdomen to break up the shape of
the abdomen a bit, giving it a more interesting
appearance.
Figure 7-18: The combined elements of the Spider Bot that required retopol-
ogy, with the legs in place. The legs are mirrored to the other side of the body.