Plant pigments in terrestrial ecosystems are crucial for sustaining life on the planet, through their pivotal role in plant photosynthesis. They are also play important protective roles and are important indicators of plant health and nutrient status. As such, a range of statistical, data-driven and physically-based methods exist for estimating leaf pigment content, from the leaf level, to larger scale mapping efforts from airborne and satellite imagery. The suitability of these methods varies according to observational scale, application, technical expertise and cost. Retrieving accurate foliar pigment values from optical remote sensing techniques is vital for the monitoring of vegetation-environment interactions and a range of terrestrial ecosystem processes.