Contents:
Impacts of Lighting
Lighting applied in a scene has by far the largest effect on the way in which fabrics are displayed. The type of light, direction, intensity and temperature all influence the way materials are displayed in a render - as would be the case in photography. This is why a render of a fabric located in an interior with warm outside daylight will look considerably different from a studio render with colder, neutral light.
The image below depicts the same 3D curtain with different light settings. From left to right: neutral white light, studio lighting from the front, studio lighting from the back and interior lighting with simulated daylight:
Lighting Considerations
When determining how a digital scene should be lit there are three areas that need to be considered. The impact of each area and the way they react with each other will have a major impact on the colours within the scene.
The first consideration is whether the background will be visible, and if it is what that background should be. The background scene will simulate outdoor light (either from the sun or moon) which will potentially shine through any windows built into the scene. The choice and placement of the background will determine the light colour and direction ultimately determining how the colours inside the scene will be affected.
The next consideration is the impact of ambient light. Just as in real life different types of bulbs emit different coloured light. This light has a big impact on the colours that it illuminates within a scene. Selecting the correct light source for the desired colour and effect is an important step.
The final consideration is the impact of the light reflected off of other objects in the scene. Placing a large green vase next to white curtains in a scene will give the curtains a green tinge.
Lighting Variables
Following is a list of the main variables that need should be defined when specifying a scene. Being specific about what type of light sources you require will ensure we produce results that are in line with your expectations.
Weather and Time of Day
A scene with abundant sunlight will lean more towards a warmer overall look with more yellow and red hues. A scene set in winter or with overcast sky will generally look cooler with more blue tinting.
Light Colour and Warmth
In computer graphics we can accurately control the color temperature of light. Blue/white light generally cools down a scene, while more yellow light adds warmth.
The image illustrates the impact of different weather on the top row, and day and night on the bottom:
Light Origin
The location of the main light source is an important variable to consider when setting up lighting. This is especially true in interior scenes which most likely feature sunlight/daylight.
To illustrate the impact of daylight flooding into a room consider curtains that might be hanging next to or in front of windows. In these cases the main light will often come from behind the drapery as daylight is the logical main light source. As such the fabric in view might appear darker as it is by definition looked at from the shadow side.
Light Strength
Naturally the stronger a light or lamp is the brighter the lit areas will be. Over and under lighting will in turn affect the way fabrics are displayed in the final render. This is an important variable for both extremely dark colours and extremely light colours - the same light can over-light very light colours, under-light very dark ones and be perfect for anything in between. Determining the thresholds for the outliers on either end of the spectrum therefore becomes important.
Light Diffuseness/Focus
Where the light comes from is another variable that has a considerable impact on the scene. An object lit head-on from the top might be easy to grasp however it does not make for a very interesting visual. Lighting from the side or even back of the object will add contrast and realism. However creating high contrast might make it harder to perceive the actual colour of the fabric as there will be smaller areas of “neutral” lighting between the highlights and shadows.
The image below illustrates the difference between soft diffuse and more intense lighting - having more intense focused light adds energy and impact to an image but also impacts the colour of the fabric: