Measurement of Sky View Factor using an arbitrary fisheye lens: A general algorithm and practical guides

• Published in: Measurement : journal of the International Measurement Confederation Vol. 245; p. 116590
• Main Authors: Wang, Shang, Li, Yanan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.03.2025
• Subjects: Fisheye lens; General SVF algorithm; Sky view factor; Standardized workflow; SVF measurement; Sky view factor; General SVF algorithm; Fisheye lens; SVF measurement; Standardized workflow
• ISSN: 0263-2241
• DOI: 10.1016/j.measurement.2024.116590

•A general SVF algorithm compatible with a random projection function is proposed.•A standardized workflow for on-site Sky View Factor measurement is provided.•A practical method for measuring SVF using an arbitrary fisheye lens is presented.•A distinction is made between the planar and the spherical Sky View Factor. Sky View Factor (SVF) is an essential parameter of urban geometry. Constrained by the prevailing equiangular-specific algorithm, on-site SVF measurement relies on fisheye lenses with equiangular projection. This results in considerable inconvenience, as a wide range of consumer-oriented devices are excluded. To enable an arbitrary fisheye lens to measure SVF, this paper proposes a general algorithm that is compatible with any random lens-specific projection function. The algorithm was validated by verifying the consistency of SVFs measured using three fisheye lenses with distinct radial lens distortions. Furthermore, practical guides are provided to minimize the discrepancies in SVF measurements resulting from the utilization of disparate fisheye lenses across different studies. The practical guides differentiate between the planar and the spherical SVF, clarify the requisite lens properties, and enumerate essential steps for applying the general algorithm. The proposed methodology reduces the hardware requirements and enhances the reliability of SVF measurements.