Seeing, understanding and designing the light

On 31 March, Sylvia Pont held her inaugural lecture as Antoni van Leeuwenhoek professor at TU Delft. She conducts research on light and the design of light. In Sylvia Pont’s work, fundamental knowledge and applied design are woven in, out and between each other. 

Although Sylvia Pont was trained as a physicist, she is less interested in light as a physical phenomenon. She is much more interested in investigating what designers can do with light. Light design offers many possibilities. For example, we can use smart light design to make our offices more pleasant to work in, to make a lifelike presentation of products in webshops and to help surgeons distinguish between diseased tissue and healthy tissue. To make all of this possible, however, a great deal of research is needed, because light is a complex phenomenon.

Everything influences everything

In our daily lives, we see light primarily indirectly, through the appearance of objects. Light makes the colours, materials, shapes and spaces of the world around us visible – but it also has an influence on the way in which we perceive objects or spaces. The type of light determines what objects look like, but light is also influenced by objects, their shape and their texture. This results in a complex interplay of light, material and shape, which makes it difficult to design light. Everything has an influence on everything. 

In addition to the light itself and the shape and material of the objects on which it falls, this complexity involves our own perception – the process through which our brains interpret sensory information. When we look at an object, we receive a two-dimensional image on the retina. From this image, our visual system must reconstruct a three-dimensional image. The two-dimensional image on the retina, however, does not provide enough information to do this. Our brains must therefore supplement these images with existing knowledge about the world and assumptions in order to arrive at a coherent image.

Those wishing to design light must know something about light itself – they must be able to describe, measure and visualise it – as well as about the influence of light on the shape and texture of objects. Finally, light designers must have knowledge about how our visual system interprets the light that has been observed. In other words, they must know something about perception.

Measurement is the key to knowledge

One way to measure the distribution of light on a point in space is to take a panoramic (360-degree) photograph. 

Such a 360-degree photograph captures the light from all directions and translates it into lighter and darker shades. This type of photograph can be displayed on a globe, or the globe can be folded out into a rectangular image. If we were to measure such a panorama for all points in a given space, all of the panoramas together would display the light as it varies by position within the space. Physicists refer to this as the light field. A light field can also be described as the sum of three physical elements that are relevant to design: light density, light vector, and light texture.

The renowned light designer Richard Kelley translated these three physical light types into the design terms of an ambient component (light from all directions), a focus component (strongly focused light) and a brilliance component (the high angle frequency of the light, or the light texture).

Both the ambient and the focus components can be measured with special equipment. Such measurements have led to the knowledge that the diffusivity of light is determined by the relationship between ambient and focus. This diffusivity plays a very important role in the appearance of objects and people (e.g. how well the three-dimensional shape can be seen). The proper measurement of brilliance has proven somewhat more complicated.

For designers, it is obviously important whether such objective measurements actually correspond to the way in which people perceive the light field. Unless this is the case, it is impossible to use them to design in any meaningful, perceptually intelligent manner.

In 2007, Sylvia Pont collaborated with Jan Koenderink at Utrecht University to investigate a method for measuring this. They asked subjects to configure the light falling on a sphere in a scene (with plastic penguins as stand-ins) such that the lighting suits the scene. The results indicated that people are quite capable of doing this, and thus that they have a good sense of the light field and the distribution of light. This study provided a scientific base for the design method developed by Richard Kelley. His work has now been embraced by many contemporary light designers as a method for achieving qualitative, perception-based design and it allows light designers to work in a scientifically sound manner.

Building on this method, doctoral candidate Tatiana Kartashova conducted an extensive study using computer models that she has developed herself to demonstrate that the sense that people have for the light field corresponds quite closely to what can be measured objectively. Subtle variations are filtered out in the process. This knowledge has been translated into computer programs in which light designers can adjust ambient and focus components and immediately see the results in a space, along with how the light distribution influences the manifestation of the space.

Manifestations

As previously noted, light also has an influence on the ways in which we perceive material, shape and space. For example, objects can look quite different in diffuse light than they do in focused light. The property of gloss is a good example. In diffuse light, all objects always appear dull. [pt 55]. This is due to the absence of sparkles and mirror reflections, as it is through such sparkles that we can see that something is glossy. In order to see that something is glossy, we must place it in brilliance or focused light.

In recent years, major steps have been taken towards a new manner of light design. Light designers are able to get to work based on all of these insights. The qualitative approach to light design is already scientifically justifiable in large part. Considerable insight exists with regard to the effects of ambient and focus components. Designers and students are busily working to design light plans.

LEDs

With regard to the brilliance component of light, we do not yet know very much about the influence of light texture, movement and colour. According to Sylvia Pont, future research should focus largely on this aspect of light. For example, additional knowledge on brilliance aspects of light is of major importance to the endless future possibilities offered by LED lighting.

LED lights are becoming smaller and smaller. Such miniaturisation offers possibilities for seamlessly integrating LEDs into material and for connecting them to sensors and to the internet. This could allow light to come from anywhere – even from floor coverings or wallpaper – and the many small points of light can together form patterns. These patterns can react in an interactive and dynamic way to aspects that are measured by sensors or controlled through the internet. For example, if these sensors measure that there are many people and a high level of tension in a space, we could simulate soothing light patterns (e.g. resembling light shining through rustling trees) in the floor covering.

Nevertheless, light is not all there is. In addition to being a light researcher, Sylvia Pont is the coordinator of the Perceptual Intelligence Lab (π-Lab) in the Faculty of Industrial Design Engineering. In this facility, she would like to collaborate with colleagues from other fields (e.g. psychology and physics) to generate knowledge on multi-sensory designs – designs in which sight, hearing, smell and taste work together and offer the user a total experience. The π-lab has already achieved recognition within the scientific world as a unique expertise centre, due to its applied, interdisciplinary approach to problems of perception in the real world.