The Sixth International Conference on Agro-Geoinformatics (Agro-Geoinformatics 2017) was held in Fairfax VA, USA on August 7-10, GEOG Ph.D. Candidate Yi Zhang presented paper entitled “Estimation of All-Sky Instantaneous Photosynthetically Active Radiation from Visible Infrared Imaging Radiometer Suite Data Using Optimization Method”. Agro-geoinformation is critical for the agricultural sustainability, food security, environmental research, bioenergy, natural resource conservation, land use management, carbon accounting, global climate change, health research, agricultural industry, commodity trading, economy research, education, agricultural decision making and policy formulation, etc. Photosynthetically active radiation (PAR) is an important input parameter for many ecosystem models, and can also be used for estimating gross primary production (GPP). The paper presents a new optimization-based method to estimate PAR from VIIRS observations and is capable of producing PAR product at the spatial resolution of finer than 1 km.