Chapter 6 - Topology. Contains a relatively gentle introduction to homology.
Graphs, Surfaces and Homology - Peter Giblin.
Builds up to homology groups via graphs and simplicial complexes.
Algebraic Topology - Allen Hatcher. Freely available online here
Computational Geometry - Algorithms and Applications by Mark de Berg, Otfried Cheong, Marc van Kreveld and Mark Overmars
This book looks at the algorithms from a computer science, rather than pure mathematics, point-of-view. So homotopy or homology is not mentioned but subjects like Voronoi Diagrams, Delauney Triangulations, Convex Hulls and many similar topics are covered.