This report summarises the activities in the project Optical Signatures during year 2000. Activities that have not previously been reported are covered more thoroughly. The project has included work within the areas of Radiometry, Background signatures, Assessment of signature, and atmospheric effects. The major activities have been: Analysis and reporting of experiment in maritime environment: Wave propagation and background signature Regular signature measurements of a terrain area in order to collect a background database Development of methods for assessment of signatures from textures.