The present invention relates to the measurement of the depth of a contaminant, e.g. snow, found on a roadway or runway from a moving vehicle by measuring the distance between where a beam of light hits the upper surface of the contaminant and where the beam of light should have hit the roadway or runway based on the position of the light source. To eliminate the effects of pitch and roll on the measurements a second light source provides a reference spot, whereby the contaminant depth calculations can be performed independent of the distance between the roadway or runway and the light sources. A video recording device, such as a digital camera, is used to capture images of the spots, whereby the distances can be measured by adding the number of pixels between the spots in the images. The present invention can also be used for determining the surface texture/roughness and the coefficient of friction of the roadway or runway by increasing the sensitivity of the recording device to capture minute changes in relative spot position, and by utilizing complex signal processing to correlate the changes in relative spot position to surface texture/roughness.