Studying light and shadow with blender

Introduction

Blender has been an artistic boon for studying light and shadow scenarios in different environments. The cycles engine is my preferred choice to simulate realistic light interactions with the environment. There are a few settings within blenders cycle engine that will need to be set to get the best results. Let start by looking at how blender handles light with the default settings to see where things go wrong.

Here is an image of a cube in a hallway using the default light settings. Now here is another image with my preferred light settings.

The importance difference to note is at the end of the hallway is a wall that will reflect light coming into it the face of the cube facing the light source. This important effect is absent in the image with the default settings. 

Blender's Light Settings

Blenders default settings do not factor in reflected light properly, so the shadows will be averaged darker than it should like in cameras. This will cause a warped perspective on how light interacts with the environment. To get the full benefits of cycles rendering you will need to go down to light settings and set it to full global illumination.

This will allow the camera to process the reflected light so you can see how it interacts with the environment. Be sure to set the clamping to zero as well to keep blender from restricting indirect light.  

The Human Eyes

The human eyes have pupils that can expand to allow for more light to enter the eyes when in dark places. When the eyes are in brighter areas the pupils will contract to let in less eyes protecting the eyes. For scenes where more information is being communicated from the shadows, blender has the option to adjust the exposure, emulating the human eyes in a way. The exposure setting under film is going to be a very important tool to get good results during rendering. The exposure setting can allow us to simulate this property of the eyes with some success allowing us to see more reflected light that would normally be absent in normal cameras.

Coming back to the cube again I have closed offf the hallway even more resulting in a darker scene.

When the exposure is raised, more light reflected light is being processed which allows us to see more of the cube.

The level of exposure that it should be set to is completely subjective depending on what you are trying to achieve. A good way to tell when you found a good exposure setting is when the shape language of the focal point is readable.

Conclusion

Blender has been a great tool for understanding how light and shadow interacts with the environment. With the correct light settings, you can get very realistic light scenarios that can be used for study. I would caution you against copying the values for an illustration work but instead using it to determine where the values are moving to. As an artist you still need to resolve how light and shadow fits within your composition, blindly following the 3D model will only hamper your progress.