Image-Based Lighting

Image-based lighting (IBL) is the process of illuminating scenes and objects (real or synthetic) with images of light from the real world. It evolved from the reflection-mapping technique in which we use panoramic images as texture maps on computer graphics models to show shiny objects reflecting real and synthetic environments. IBL is analogous to image-based modeling, in which we derive a 3D scene’s geometric structure from images, and to image-based rendering, in which we produce the rendered appearance of a scene from its appearance in images. When used effectively,IBL can produce realistic rendered appearances of objects and can be an effective tool for integrating computer graphics objects into real scenes.

The basic steps in IBL are
1. capturing real-world illumination as an omnidirectional, high dynamic range image;
2. mapping the illumination onto a representation of the environment;
3. placing the 3D object inside the environment; and
4. simulating the light from the environment illuminating the computer graphics object.

Figure 1 shows an example of an object illuminated entirely using IBL. Gary Butcher created the models in 3D Studio Max, and the renderer used was the Arnold global illumination system written by Marcos Fajardo. I captured the light in a kitchen so it includes light from a ceiling fixture; the blue sky from the windows; and the indirect light from the room’s walls, ceiling, and cabinets. Gary mapped the light from this room onto a large sphere and placed the model of the microscope on the table in the middle of the sphere. Then, he used Arnold to simulate the object’s appearance as illuminated by the light coming from the sphere of incident illumination.

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