  A recent proposal has shown that it is possible to perform linear-optics
quantum computation using a ballistic generation of the lattice. Yet, due to
the probabilistic generation of its cluster state, it is not possible to use
the fault-tolerant Raussendorf lattice, which requires a lower failure rate
during the entanglement-generation process. Previous work in this area showed
proof-of-principle linear-optics quantum computation, while this paper presents
an approach to it which is more practical, satisfying several key constraints.
We develop a classical measurement scheme, that purifies a large faulty lattice
to a smaller lattice with entanglement faults below threshold. A single
application of this method can reduce the entanglement error rate to $7\%$ for
an input failure rate of $25\%$. Thus, we can show that it is possible to
achieve fault tolerance for ballistic methods.
