The use of the empirical line method to calibrate remotely sensed data to reflectance

To have lasting quantitative value, remotely sensed data must be calibrated to physical units of reflectance. The empirical line method offers a logis tically simple means of generating acceptable estimates of surface reflecta nce. A review and case-study identify the ease with which this method can b e applied, but also some of the pitfalls that can be encountered if it is n ot planned and implemented properly. A number of theoretical assumptions an d practical considerations should be taken into account before applying thi s approach. It is suggested that the empirical line method allows the calib ration of remotely sensed data to reflectance with errors of only a few per cent.