@article{pub6716,
    abstract = {Developing robust light transport simulation algorithms that are
capable of dealing with arbitrary input scenes remains an elusive
challenge. Although efficient global illumination algorithms exist,
an acceptable approximation error in a reasonable amount of time
is usually only achieved for specific types of input scenes. To address
this problem, we present a reformulation of photon mapping
as a bidirectional path sampling technique for Monte Carlo light
transport simulation. The benefit of our new formulation is twofold.
First, it makes it possible, for the first time, to explain in a formal
manner the relative efficiency of photon mapping and bidirectional
path tracing, which have so far been considered conceptually incompatible
solutions to the light transport problem. Second, it allows
for a seamless integration of the two methods into a more robust
combined rendering algorithm via multiple importance sampling.
A progressive version of this algorithm is consistent and efficiently
handles a wide variety of lighting conditions, ranging from direct
illumination, diffuse and glossy inter-reflections, to specular-diffusespecular
light transport. Our analysis shows that this algorithm
inherits the high asymptotic performance from bidirectional path
tracing for most light path types, while benefiting from the efficiency
of photon mapping for specular-diffuse-specular lighting effects.},
    year = {2012},
    title = {Light Transport Simulation with Vertex Connection and Merging},
    editor = {Julie Dorsey},
    journal = {ACM Transactions on Graphics (TOG)},
    volume = {31},
    pages = {1-10},
    publisher = {ACM},
    author = {Iliyan Georgiev and Jaroslav Krivanek and Tomás Davidovic and Philipp Slusallek}
}