Recreating the Sodium Vapor Matting Process

We present a Sodium Vapor Matting (SVM) system built from off-the-shelf components allowing simultaneous capture of a full-color foreground subject and an accurate holdout matte. We use a beamsplitter cube and two filters to image the sodium vapor wavelength independently of the rest of the visible spectrum. We build custom sodium vapor light sources for illuminating the background, and aim synchronized digital cinema cameras into the filtered prism to record the foreground and the matte. We process several composite shots using the system, using the matte and a clean plate to subtract visible light in the subject's background and to hold out the alpha region from the new background.