Don’t forget the skybox

In many projects that I am part of I have noticed that people ignore the skybox, time of day and color of the sun when lighting their scene. More importantly, the skybox do not match any of the choices. So let us just quickly go through why picking the right skybox is important along with the sunlight settings. To understand that we need to look at some reference images and understand how light works.

If we look at the image below, it is brightly lit and you will see most of the colors that nature actually has, this is because the color of the sun is closer to white/yellow at this time, and the dark shadows under the tree shows generally the time of day and position of the sun.

If you look at the next image you will notice that nature has different value (saturation) but in general if the terrain is similar, it has the same colors. However, you might notice that depending on the time of day and sun position, the color yellow-orange pops up more. This effects the saturation, value and tone of the color despite it being somewhat similar in color if both were in the same time of day, sun position and so on.

So what does this mean? Well, to ensure you kind of understand the concept of how environment changes and that the skybox is a big reason for this. Let us turn these into greyscale. Look at them and continue reading after, and only after you notice the subtle difference.

So maybe you noticed that the value/strength of the colors are different even though they are for example green, yellow or blue. This has something to do with saturation and ton of other things, but our focus is to understand and assume that the sky affects the light in such a way, that the value of the color changes depending on the skybox. As the skybox aka sky creates ambience and fills in the environment with the color that is in the sky and of course, time of day. Below are both color swatches put in the same image, with a neutral grey background. Notice how two of the grey are almost gone (red arrows), and if you look hard enough you will notice that every circle overlaps another circle. This tells us that they are different in value. Even the darkest ones on top right, are different.

This is why skybox is important and picking the correct one for the correct time of day is also vitally important. Here are some examples to make sure you understand the difference. For this we are going to use Unity Engine to quickly end this blog post visually.

This is how many people do their light, even after changing the skybox, so what is wrong in this image in terms of skybox and lighting?

1.       The sky is clearly red/orange which means the time of day is either sunrise or sunset.

2.       The light source itself is white, when it should be yellow/orange.

3.       The direction of shadows and shading do not match but do notice the orange glow on the objects, coming from the skybox.

So let us look at the correct version if you light it correctly based on skybox, time of day and sunlight settings.

You can clearly see the brightest spot in the skybox is to the right, you see the time of day, you see the glow on the sphere, you see the shadows and color. Hopefully that gives you some insight on what you keep in mind when you light your next project.

A)      Skybox color, sunlight direction and time of day

B)      Direction of the sun source to create the correct shadows, in both intensity and length.

C)      The correct color depending on time of day, sky box and style.

I hope this was a quick and easy read, and useful. Be sure to read my previous post and stop by my channel at https://www.youtube.com/user/Cyberiusx

Cheers

Amit