Towards a better understanding of in-situ canopy measurements used in the derivation and validation of remote sensing leaf area index products

Remote sensing products, such as the leaf area index, are available from different remote sensing platforms and sensors with different resolutions. There is a clear need for the remote sensing community to acquire a better understanding of the measurement techniques frequently used to acquired these field measurements. Examples of field measurement protocols for the LICOR’s LAI-2000, 3rd Wave Engineering’s Tracing Radiation and Architecture of Canopy (TRAC), hemispherical photography systems, and portable LIDARs such as the Optech ILRIS 3D are examined. The advantages and disadvantages of these four types of instruments are discussed based on price, durability, usable conditions, and information retrieval. The comparison shows that the hemispherical photography is the best value for the price since it can be used to get almost all parameters that the LAI-2000 and TRAC can measure together while the LIDAR system can acquire the most information of all four systems, but at a very high price that makes it too expensive for widespread used today.