Description

This Technical Report summarizes visual photometric measurement methods which can provide visually meaningful assessments of light. They can be more complicated than the simple use of of a V(lambda)-corrected physical photometer, and in addition require some understanding of the visual system and how it works. Their advantage is that the assessment of light bears a logical relationship to the human perception of light.

For photopic vision and luminances larger than several cd/m2, ordinary physical photometers corrected to V(lambda) give visually accurate measures for small, centrally fixed, broad-band lights. For other applications, a different luminous efficiency function should be employed. In order to utilize the appropriate function, one must either measure the spectral distribution of radiant power directly or correct the V(lambda) response of the photometer to the appropriate luminous efficiency. An alternative solution is to calculate mathematical formulas specifically developed for this purpose. This method is potentially the most useful since different formulas can be developed for different applications (for example, two degree or ten degree fields).

It is based on established CIE data, and no additional measures need to be developed.For scotopic vision, an assessment of radiant power is made with respect to the scotopic luminous efficiency function V'(lambda) by means of an appropriately corrected physical photometer, by radiance measurement, or by visual photometry. In mesopic photometry, the photopic and scotopic contributions of the light must be assessed. An estimate can be obtained by combining the photopic and scotopic luminances non-linearly. A more precise measure can be obtained by using three or, still better, four quantities based on X10, Y10, Z10, and V'(lambda).

The document consists of 40 pages, 4 figures and 9 tables.

Description

This report presents a method which can serve as a basis for interior lighting design calculations. The method does not rely on standard light distributions for luminaires, is not restricted to regular arrangements of luminaires, and can be used in situations where the interior is a rectangular parallelepiped, the task plane can be regarded as one of the room surfaces, the room surfaces, reflect uniformly and according to Lambert's law, the direct flux on the task plane does not vary significantly when the luminaires are rotated about their vertical axis.

See also CIE 52-1982 Calculations for Interior Lighting: Applied Method.

The publication contains 60 pages, 2 figures and 54 tables.