3D Rendering - Light setup

[a_bertrand]

Lighting a 3D scene is one of the most important part (as well as the texures I will discuss later on), unfortunately 3D artists, specially those starting in this field under-estimate the lighting or have no clues what they should do.

Here I will not go in deep into all the tricks you can do to improve the lighting of a scene however I will show how some setup can dramatically improve the render quality (and some time increase dramatically the render time as well).

Let's start with the scene by itself viewed with the wireframes to show how simple the scene is:

As you can see the scene is a simple as some primitive shapes inside a cube (primitives are shapes which the 3D software can create for you, like cubes, spheres, cylinders etc.). Shapes do have a simple shading which include a color and nothing else. All this is within a cubic shape.

To start let's light up the scene with a single "point light" which is nothing else as a single point where the light will be produced. Think about an extremely small light bulb. You see that we see at least the shapes... but the shadows are very defined, unnatural and extremely dark. This is the classic "newbie" setup.

The second trial, is simply to change the light type from a point light to an area light. An area light is like a rectangle which produce the light from all the area of the rectangle. The advantage of this is that you get already a much more natural lighting and the hard shadows (very defined one) are now transformed in soft shadows. Still the image is dark and there is a lot of black areas where you see nothing. If you want to go from there you should add some more lights to increase the lighting of the scene.

Now if your software is more or less a complete 3D package you should have something called "Global Illumination" which is nothing else as one or more algorithm which calculate more accurately what the light do within your scene, light start to bounce on the walls back to the objects. This techniques allows to have a much more natural lighting with little efforts from the artist himself, beside some tweaking of the parameters that's it. However, as always, it is not completely without side effects, one of which is the render time. The point light image took about 3 sec to render and this one took 58 sec.

Now as you see you start to get indeed a better image as it contains less completely dark areas and offers more shades. Yet it is not finished we can further improve it by increasing the indirect bounces. which means, instead of stopping after the the first bounce we will do more bounces of light... and this will have yet another good advantage: light bounced out of colored objects will get a tint and propagate this tint around. It will also further reduce the dark areas. Of course the render time will climb again but not that much as I didn't placed too much secondary rays (rays after the first bounce): final time 61 sec.

Check the wall on the right near the blue ball... you will spot there the blue tint I was talking about as well as under the red cone.

[Lilith]

This is great stuff and easy to understand. Please post more like this!