In my previous post, I wrote very briefly about anĀ important improvement to the irradiance caching algorithm – irradiance gradients – and I’m going to expand on rotational gradients this time. Gradients The gradient of a function represents both the direction and rate of change of that function as the inputs vary. For a one dimensional function this is simply the derivative of the function. As you move into higher dimensions, you need to consider which coordinate system the inputs for the function are specified in, as this will change…

# Category: Irradiance Caching

## Irradiance Caching: Part 1

Solving the rendering equation with even just one bounce of indirect lighting can take a long time. The majority of time spent rendering a frame is in estimating the lighting integral. For example, rendering a single bounce of indirect lighting at 720p resolution with 256 sample rays for a Monte Carlo estimator requires about 237 million rays to be cast. This doesn’t even include the rays needed for sampling the lights for direct lighting, so in practice, the total will be even higher. One interesting observation made by Greg Ward…