{
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  "schemeVersion": "2025-07-25",
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  "uuid": "aeda1c37-8b01-42b8-8c6b-1806d0d95708",
  "prefLabel": "BI-DIRECTIONAL SURFACE REFLECTANCE",
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      "prefLabel": "SURFACE RADIATIVE PROPERTIES",
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  "definitions": [
    {
      "text": "Bidirectional reflectance is a foundational concept in optics and photometry, describing how a surface reflects light in different directions depending on both how it is illuminated and from which direction it is observed. Unlike simple reflectance or albedo, which average over all directions, bidirectional reflectance rigorously accounts for the geometry of both the source and the observer. This concept is crucial in fields as diverse as remote sensing, material science, and computer graphics. The key mathematical tool for describing this angular dependence is the Bidirectional Reflectance Distribution Function (BRDF), which provides an exact relationship between the incident and reflected radiance as a function of their respective angles and wavelength.\n\nBy capturing the effects of surface microstructure, material properties, and geometry, BRDF forms the backbone for analyzing and simulating the appearance of real-world materials. In remote sensing, accurate knowledge of bidirectional reflectance is critical for radiometric calibration and for extracting reliable information about our environment from satellite imagery. In computer graphics, BRDFs enable photorealistic rendering by simulating how light interacts with virtual materials under any lighting condition. In material science and optics, BRDF measurements support the design and evaluation of advanced coatings, paints, and optical surfaces.\n\nUnderstanding bidirectional reflectance is therefore essential for any application that relies on the appearance, characterization, or radiometric measurement of surfaces.",
      "reference": "https://www.tarmacview.com/glossary/bidirectional-reflectance/"
    }
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