Physics/Science of Light (PART 8)

Physics/Science of Light

(How you could implement it + create dramatic compelling art scenes)

SUBSURFACE SCATTERING

In this picture, the head of the fish protruding out of the water is clear and visible to us, but when when we get to the body, it starts to get fuzzy pretty quickly.

This is subsurface scattering.

What happens in subsurface scattering is, when specific areas of a surface are transparent and light hits those areas, this causes the molecules/atoms to scatter the light. Therefore, what comes out of the opposite end is not the image of what you saw coming into the object but is just a general approximation of the light that came in the other end. Generally speaking, the denser the object is, the more atoms there are and the less subsurface scattering there is.

Cases which almost always give subsurface scattering an opportunity to take place is when a surface is made up low energy/reactive atoms that allow light to pass through them.There are cases when a dense object can allow some light to pass through them, however, those are exceptions.

Of course different surfaces are going to respond differently, the chocolate on top (along the edges) is getting a bit of subsurface scattering whereas the caramel underneath gets a lot more light scattering through it.

You've got the caramel colour as it is but when the light passes through it you can see it getting saturated along the edges.

Let's talk about one other event that happens with subsurface scattering, such as the

behavioural activities it endures while it passes through a solid; causing it to change in colour.

When the surface is made up of atoms/molecules of a particular colour (ie. red), that light shining through the transparent area will naturally take on that particular colour(ie. red).

When an area of the surface is very transparent sometimes light can pass through it reaching the shadows; allowing the subtle intermixing of the colours from the transparent area with the shadows.

There's another phenomenon going on here based on quantum principles of light and how it is used to study the behaviour of the wavelengths.

Blue is short wave-length, meanwhile , the red wavelength is long.

The shorter the wavelength, the higher the probability that it's going to interact with the atoms. A good way to remember this is, if you try to shoot x-rays through something (x-rays have a very high wavelength) they tend to pass right through the skin but as soon as they reach the bones-they stop.

Whereas radio-waves, (x-rays and radiowaves are just light except we can't see this form of light) they tend to be very long in wavelength and because of that they're able to pass through the walls and get you the signal that you need.

So with light passing through a solid like that, that increased probability of interaction means we'll lose the blue end of the spectrum and the red end of the spectrum comes out more.