Estimating coral reef slope or camera pitch from video

Area estimation of coral colonies from images can be improved by eliminating the distorting effect of camera rotation angle or reef slope. We propose a method that estimates the angle between reef and camera plane using the tracks formed by the movement of image features in the video. Estimates obtained from experimental setup show the effectiveness of the technique, with acceptable error for small angles. The technique can be used on benthos monitoring setups to provide good area estimates without any additional instrumentation.