Bidirectional reflectance distribution function

Hello there! Today, we are going to learn about a big, long and fancy word - bidirectional reflectance distribution function or BRDF in short.

Let's start with what "Bidirectional" means. It means going in two different directions. For example, if you're standing in the middle of a room and you shout "Hello!" your voice will bounce off the walls and reach your ears from different angles. This is because the sound waves travel in two different directions - to the walls and back to your ears.

Now, let's talk about "Reflectance". Have you ever seen your reflection in a mirror? That's because the mirror reflects the light that falls on it. Reflectance is the measure of how much light is reflected off an object. So, if an object is very shiny and smooth, it will reflect a lot of light.

Finally, let's talk about the "Distribution Function" part of the word. Imagine you have a bag of marbles and you pour them out on the ground. The way the marbles are distributed on the ground is just like how the reflectance of light is distributed on a surface.

Now let's put all of these words together to understand what BRDF means. When light hits an object, it can bounce off in many different directions. The BRDF tells us how much light is reflected in each of those directions. It's like a map that shows us where the marbles will end up after they're poured out. Some surfaces, like a shiny mirror, have a very specific BRDF because they mostly reflect light in one direction. Other surfaces, like a pillow, have a more scattered BRDF because they reflect light in many different directions.

So, in conclusion, the BRDF is a map that tells us how much light is reflected in different directions when it hits an object. It's useful because it helps us understand how light interacts with different surfaces and materials, which is important in many science and engineering fields.