It's because tracing a sphere is quadratic equation solve. The guy in the video, Eric Haines, published an article about how to improve sphere tracing precision

It's because tracing a sphere is quadratic equation solve. The guy in the video, Eric Haines, published an article about how to improve sphere tracing precision. It's in the freely available Ray Tracing Gems book. https://link.springer.com/content/pdf/10.1007%2F978-1-4842-4427-2_7.pdf https://link.springer.com/content/pdf/10.1007%2F978-1-4842-4...