Video range imaging

Video range imaging is a technique developed to capture surface roughness of large scale surfaces (mm-scale and larger). This technique yields information that is similar to the confocal microscope, but at a much higher scale. In this technique, the sample surface is painted white or coated with a uniform light-colored coating. The surface is then flooded with a colored fluid, such as water with a blue dye, so that when viewed from above, the deep regions appear dark relative to the high areas. A video image may be captured from above. The resulting grey tones in the image may be calibrated with depth data to permit quantification of parameters such as roughness number.

The raw grey image on the left is a concrete surface that has been intentionally roughened in preparation for application of repair materials. The image on the right is the 3-D rendoring of the same image. (10 cm full width) [Credit: David A. Lange, UIUC. Acknowledge is also given to the International Concrete Repair Institute because the concrete surface is part of their standard concrete profiles used in ICRI Guideline No. 03732.]