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ISO 23599-2012 pdf free download
ISO 23599-2012 pdf free download.Assistive products for blind and visionimpaired persons Tactile walking surface indicators
Produits dassistance pour personnes aveugles ou visuellement affaiblies — Indicateurs tactiles de surfaces de marche.
Luminance contrast can be determined by measuring the luminance of the TWSI and comparing it with the luminance of the surrounding or adjacent surface, within a width of 100 mm on both sides of the TWSI. Alternatively, it can be determined by measuring the reflectance of the TWSI and comparing it to the reflectance of the surrounding or adjacent surface.
Luminance or reflectance can be measured by one of two major methods, depending on the measurement instruments:
a) contact type, and
b) non-contact type
All devices should be calibrated to the spectral sensitivity of the human eye, corrected to meet the CIE photopic curve, V(A).
All TWSI and surrounding or adjacent surfaces should be measured under both wet and dry conditions. When textured or non-uniform surfaces are being measured, multiple measurements should be made and averaged. When discrete TWSIs are measured, the field or measurement should include only one TWSI and no surrounding or adjacent surface.
TWSIs and surrounding or adjacent surfaces should be measured under the type of illumination that is used in the relevant environment.
It is important to read the instruction manual of any instrument used, and to understand and apply the correct procedure and method of measurement.
A.2.2 Measurement with non-contact-type Instruments
Non-contact-type instruments measure the luminance of a small, defined, surface area from some distance away from the surface being measured. Non-contact-type instruments are usually fixed onto a tripod stand. The surface area being measured Is determined by the angle of the measurement field of the instrument and the distance of the instrument from the surface being measured.
Non-contact-type instruments have the following advantages:
— measurements can be taken at the typical angles of perception of people who use TWSIs:
— objects with colour or surface irregularities can be accurately measured, provided that the instrument used has a measurement field wide enough to include such irregularities.
Non-contact-type instruments have the following disadvantages:
— they require stable ambient light conditions for accurate measurement;
— if luminance. L, Is used to determine luminance contrast, they require that the two surfaces to be compared be measured under the same light conditions.ISO 23599-2012 pdf free download.
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