Here’s how to craft your 3D lighting using a little known technique.
Light like Caravaggio
Creative lighting is one of the most powerful tools we have in producing beautiful imagery. However, there is more to an image than it’s surface beauty. We often have a visual story to tell. One of the major devices we have in telling this visual story is by controlling what the viewer sees and what they cannot see. Through creative use of light and shadow, we can guide their eye through a scene.
Caravaggio was an Italian painter active in the late 15th and early 16th centuries. He’s widely recognised as a pioneer of an anatomical realism and for his use of dramatic lighting. He achieved this level of realism through observation and pure skill. He never had the benefit of studying photography, there was no global illumination option in his pallette.
Take a look at his work and you’ll see a true understanding of the power of light to evoke mood. Technically, he understands the principles of light transportation and had the masterly skill to lay this down in paint.
And do you know what I think? If you introduced Caravaggio to a 3D scene and asked him to light it, he wouldn’t need or have a desire to use global illumination. I’m pretty sure that after a couple of minutes twiddling the light settings he’d turn around, and in a thick 15th-century Italian accent ask you,
‘So, how do I control the decay of the lights in this scene?’
Because that’s what he does. Whilst he had an uncanny (for the time), mastery of light and it’s behaviour, he also wanted ultimate control. He controlled how much of a surface was fully lit, what’s in partial shadow and what’s in full shadow. He’s in total control of you, the viewer.
Wouldn’t we all like some of that ability, both artistically and technically?
Let’s learn how to sculpt with light
So often as 3D artists we only pay attention to a light’s intensity setting. Turn it up, more light. Turn down the intensity, less light. But if you’re only using the intensity setting to control the effect of you’re lighting, then your only dealing with half the story.
There is a particular property of 3D lights that modern render engines mostly automate. This property is light attenuation. They do this for a good reason (more on that later), but taking manual control over this property can really have a dramatic effect on your images.
So what is light attenuation?
Light attenuation is the name given to describe how light behaves over distance.
Google the term and you’ll see a lot of scary-looking graphs and formulas. For artistic purposes let’s keep it simple.
‘Light attenuation means that a light’s intensity gets weaker the further it travels from its source.’
Picture a lit candle. As we travel away from the light-emitting flame, the intensity of the light drops quickly. This gives the candle a perceptibly high rate of attenuation.
Now think of a LED pocket torch. Its job is to pump out as much light as possible in a small form factor. This light source is engineered to be as constant, focused and far-reaching as possible. So we perceive the torch light to have a lower rate of attenuation than the candle.
No matter what the light source, large or small, light diminishes at the same rate of change. This rate of change is described by the inverse square law.
Do you recognise this term? If you’ve spent time in the settings of your CG lights, then your probably familiar with it. It’s the default option on light sources as it’s the most physically accurate. Therefore, it produces the most realistic results out-of-the-box.
Physically accurate equals good. Right?
If your aim is to produce realistic images whilst following the rules of traditional photography, then yes, being physically accurate in your scene is important. Not just in lighting, but in all areas. From design to scene scale, through to model detail and shading.
So whilst we want to be accurate in most scenarios, as artists, we aim to create visual drama. Depth. Contrast. Light and shadow. This is what makes for interesting imagery. So if we need to bend the rules a little to achieve these results, that’s also OK, right?
Taking back control
Just as Caravaggio did in paint, we wish to do in pixels. And to do this we need to gain fine control over our CG lights by manually adjusting their attenuation. So let’s get into the details of how we achieve this.
Disclaimer: I’ll be using Arnold (Maya) to illustrate this technique. In the past, I have also used this method with 3DSMax and Vray.
Using Caravaggio’s paintings as inspiration, we’re going to replicate some of his characteristic lighting in a 3D scene. We’ll keep with his classical themes and use a selection of scans from the SMK — the Statens Museum for Kunst here in Copenhagen. These scans are freely available from their myminifactory webpage -
I’m going to experiment using an area light. You could also try with a spot-light. I’m using the scan called the ‘presentation in the temple and flight into Egypt’. This relief is fairly flat in nature, so allows us to more easily see the lighting zones we’ll create over the whole surface.
Our aim is to light this scene subtly whilst highlighting the figure holding the child. We’re going to focus the viewer’s eye on this particular area, and we’ll achieve this by carefully crafting light and dark using the lights attenuation controls.
I’ll start by adjusting the light’s intensity (Arnold calls this exposure), so the full height of the sculpture is visible. It’s important to remember that Arnold is automatically applying realistic light attenuation to this area light. That’s why the resulting light is already visually appealing, and in-line with what we would expect to see.
But how do we create zonal lighting? In Caravaggio’s work, we see that the light is focused on the parts of the image important to the story. In this example, I want to focus your eye on the child carrying figure. By controlling the light gradients and how we travel from light to shadow, I think we can emphasize him.
We’ll use a combination of two controls. The area lights spread parameter and Arnold’s Light Filters function. With the area light selected, go into the Arnold Area Light Attributes and locate the Light Filters section. Click on the Add button, and a pop-up window will display the available options.
With a Light Decay added to the area light, double-clicking it will bring up the Near and Far attenuation controls. This is where the magic happens.
Using the Near Attenuation control allows you to set the point at which the light starts, and the point at which it reaches it’s maximum output. By adjusting the Far Attenuation you're able to kill off the light's intensity. Take a look at the diagram below, for an illustration of what’s happening.
So what does this means practically? It means you can break the law of inverse square attenuation, and craft the light with extreme precision. Take a look at the below image where I have used the far attenuation control to control exactly how far the light travels into the scene. Note that I have also lowered the area light’s spread value to narrow the focus, making it act more like a spot-light.
Breaking the rules
As stated earlier, we are now breaking the rules of physically correct light behaviour with these controls. Gone is the natural intensity curve produced by the inverse square law. Now we are manually adjusting the light intensity based on our requirements and artistic judgement.
And when used correctly, it’s a great option to have in our lighting arsenal. The image below is lit with a single area light using light decay filter to mimic the lighting style of Caravaggio’s work. It’s extremely difficult to achieve such a fine level of control using the standard light attenuation models.
This handcrafted approach to lighting is fun and deeply satisfying. I promise you that when used judiciously, you’ll now look at each new lighting situation with renewed confidence, safe in the knowledge that the scene lighting is fully under your control.