  Many Monte Carlo light transport simulations use multiple importance sampling
(MIS) to weight between different path sampling strategies. We propose to use
the path throughput to compute the MIS weights instead of the commonly used
probability density per area measure. This new formulation is equivalent to the
previous approach and results in the same weights as well as implementation.
However, it is more intuitive and can help in understanding the effects of
modifications to the weight function. We show some examples of required
modifications which are often neglected in implementations. Also, our new
perspective might help to derive MIS strategies for new samplers in the future.
