  In this paper we study the problem of designing a distributed graph
visualization algorithm for large graphs. The algorithm must be simple to
implement and the computing infrastructure must not require major hardware or
software investments. We design, implement, and experiment a force-directed
algorithm in Giraph, a popular open source framework for distributed computing,
based on a vertex-centric design paradigm. The algorithm is tested both on real
and artificial graphs with up to million edges, by using a rather inexpensive
PaaS (Platform as a Service) infrastructure of Amazon. The experiments show the
scalability and effectiveness of our technique when compared to a centralized
implementation of the same force-directed model. We show that graphs with about
one million edges can be drawn in less than 8 minutes, by spending about 1\$
per drawing in the cloud computing infrastructure.
