Driver Visibility Quality:An Electro-Optical Meter for In-Vehicle Measurement of Modulation Transfer (MTF).

摘要

In order to provide a practical means for developing and monitoring standards of driver visibility quality,an electro-optical MTF meter was designed and delivered to NHTSA. Tests were conducted with Landolt ring targets to relate human vision to meter readings,under various types of optical degradation (windshield fogging,icing,dirt film,etc.);there was excellent agreement between meter readings and visual test measures,confirming that the visibility quality meter (VQM) can stand in as an 'average observer'to determine if visibility quality meets minimum requirements. The VQM is a rugged and simple solid-state device with an oscilloscope display of image luminance cross-section;image contrast values are read directly from the display for determination of MTF (i.e.,contrast transmittance). The large body of visual contrast-sensitivity data available in the literature can be directly related to VQM readings,thus providing visibility standards for targets of a given size,shape,distance,luminance,and viewing condition.