plenoptic

Plenoptic is an adjective used in optics to describe a complete description of the light in a scene. In imaging, the plenoptic function is a high-dimensional radiance function that encodes how light arrives at or leaves from every point in space across directions, wavelengths, and time. A common informal form is L(x, y, θ, φ, λ, t), representing the radiance at position (x, y) in direction (θ, φ) for wavelength λ at time t.

The concept was formalized in the plenoptic function framework by Adelson and Bergen in 1991 as a unifying model of vision and imaging. The function provides a theoretical basis for describing how a scene would look from any viewpoint and under any lighting, and it underpins methods for extracting views, depths, and appearances from captured data. In practice, researchers often use reduced forms, such as a 4D light field L(x, y, θ, φ) that samples spatial and angular information, with extensions to include wavelength (5D) and time or motion (6D or higher).

Technologies that capture plenoptic data include plenoptic or light-field cameras, which place a microlens array between the main lens and the sensor to record angular information about rays. Other approaches use camera arrays or computational imaging pipelines to sample the plenoptic function. The resulting data enable post-capture refocusing, viewpoint changes, depth estimation, and 3D reconstruction, offering new capabilities for imaging and graphics.

Limitations of plenoptic imaging include trade-offs between spatial and angular resolution, substantial data volumes, and calibration complexity. Nevertheless, the field continues to evolve, with ongoing work on higher-resolution capture, more efficient data processing, and improved reconstruction algorithms.