For this lab, I implemented
problem 7.1 of the pbrt book, which deals with sampling patterns.
Specifically, it asks to implement multi-jittered sampling
and distribute the samples in different ways to see the effect.

## Methods

To distribute the multi-jittered pattern to the image samples, I came
up with two methods.

1. Give the i-th image sample the i-th row of the pattern.

2. Give the i-th image sample a random row of the pattern.

The first method works better because the second method can repeat image samples, so the second method is less well distributed.

## Images

All images were rendered with 8 samples per pixel. The first
picture is the regular stratified sampling. The second is the
one with the multijittering using method #1. The third is
using mutijittering along with method #2.

1. Give the i-th image sample the i-th row of the pattern.

2. Give the i-th image sample a random row of the pattern.

The first method works better because the second method can repeat image samples, so the second method is less well distributed.

Stratified | Multi-jittering (Method #1) | Multi-jittering (Method #2) |