An example of a real-world application of implicit surfaces is in video game development. If you have an object (usually encapsulated in a mesh) and you want to test whether it's collided with another object in a given frame, you can use implicit surfaces as we do above to see if a point in the object's mesh is inside another object's mesh (hence they've "collided"). For Unity (and probably other engines as well), this is called a mesh collider.
An example of a real-world application of implicit surfaces is in video game development. If you have an object (usually encapsulated in a mesh) and you want to test whether it's collided with another object in a given frame, you can use implicit surfaces as we do above to see if a point in the object's mesh is inside another object's mesh (hence they've "collided"). For Unity (and probably other engines as well), this is called a mesh collider.