Daytime Line Marking Luminance
It is important that road markings have sufficient luminance, which provides a contrast with the road surface in daylight. The Luminance Coefficient under Diffuse Illumination Qd (mcd.m-2.lx-1) is a standard measurement of the quality of line marking. Taking this measurement from digital video is difficult as the Diffuse Illumination is variable due to lighting conditions. Impulse Geophysics, through research, has developed an algorithm to convert bitmap luminance to the Luminance Coefficient under Diffuse Illumination. Additionally, variable lighting is compensated for by using a correction factor using luminance measurements from the road surface surrounding the line marking. All measurements are made using machine learning, neural networks and image recognition to locate and test the line markings.
Line Marking Contrast, the ratio of line luminance and average pavement surface luminance is the most important factor relating to daytime line marking visibility. This is automatically measured comparing the line marking luminance and the road surface luminance. These parameters are automatically measured for the Luminance Coefficient analysis and therefore Line Marking Contrast is automatically output.