New directions are rapidly emerging in modern photometry that promise to revolutionize our understanding of light, hence improving our ability to communicate lighting designs. Some images are photo metrically accurate representations of real-life situations, such as the digital image of the atrium, San Francisco Museum of Modern Art that has received international publicity and was awarded a first price in photo-realism at the San Francisco AIA.
There are three converging directions in photo metric research: near-field photometry, three-dimensional illuminance, and radiosity. Of these, radiosity is of great importance to an architectural computer renderer.
Radiosity versus Ray Tracing.
Radiosity and ray tracing algorithms are very different and yet they are in many ways complementary. Ray tracing is very versatile because of the large range of lighting effects it can model. Radiosity is an advanced form of ray tracing. Images
produced using ray tracing techniques tend to look somewhat artificial, with sharp-edged shadows. Although they look realistic, they are not suitable for detailed photo metric analysis.
Ray tracing a complex 3D model may take hours for a computer to render. It is important to understand the technology of both techniques to achieve the required results. Radiance, an application program developed by the Lawrence Berkeley Laboratory department of Day-Lighting, was originally developed as a research tool for predicting the distribution of visible radiation in illuminated spaces. It uses the technique of ray tracing that follows light backward from the image plane to the source(s).
Because it can produce realistic images from a simple description, Radiance has a wide range of application in graphic arts, lighting design, and computer-generated architecture. Radiance is available free of charge but it has a complex user interface, and is therefore difficult to use.
Lightscape Technology, now part of Autodesk and incorporated into 3D Studio Max., was another very powerful application ( PC Platform only) it was the first visualization application based primarily on radiosity techniques. Neither radiosity nor ray tracing offers a total solution
for simulating all global illumination effects. Radiosity excels at rendering diffuse-to-diffuse inter reflections and ray tracing excels at rendering specular reflections. This post-process radiosity and ray tracing solution offers the best of both worlds.
It is possible to combine a ray tracing post-process with a specific view of a radiosity solution to add specular reflections and transparency effects. This radiosity solution replaces the inaccurate ambient constant with accurate indirect illumination value, therefore generating a much more realistic image. Lighscape is probably the most accurate and innovative application today for calculating and rendering accurate lighting simulations of 3D architectural digital
models. The application uses a proprietary radiosity technique to calculate direct illumination and indirect diffuse inter reflections of light between surfaces. An integrated ray tracer is also provided to add specular highlights and reflections to specific views. All surface materials are defined according to the physical characteristics of diffuse and specular reflectivities. Lightscape calculates all light energy distribution in physical photo metric units. There is no limitation to the number of lights which may be included in the scene.
Is Virtual Reality the Future of the Design Profession?
Today we have the technical ability to allow the designer and the client to realistically explore and experience
unbuilt projects. This virtual space exploration has its price: low resolution display, chunky headsets, electronic gloves, and very expensive computer systems. The problem and the danger with virtual reality technology is its side effects, such as motion sickness.