Field Data Acquisition

EOLAB has extensive experience in participation and coordinate field campaigns. We have several devices  to obtain in situ biophysical parameters (LAI, FAPAR, FCover), including hemispherical digital photography, ceptometers and LI-COR LAI 2200C plant canopy analyser.

  • We have a Digital camera (CANON EOS 6D and a fisheye converter SIGMA 8mm F3.5 – EX D) to acquire Digital Hemispheric Photographs (DHP). Hemispherical photos allow the calculation of LAI, FAPAR and FCover measuring gap fraction through an extreme wide-angle camera lens. The hemispherical photos acquired are  processed with the CAN-EYE software (developed by INRA) to derive LAI, FAPAR and FCover.
  • The AccuPAR model LP-80 is a lightweight, portable, linear photosynthetically active radiation (PAR) sensor. It lets you measure canopy PAR interception and calculate leaf area index (LAI) at any location within a plant or forest canopy.
  • The LI-COR LAI 2200C plant canopy analyser calculate Leaf Area Index (LAI) and other canopy attributes from light measurements made with a “fish-eye” optical sensor. Measurements made above and below the canopy are used to calculate canopy light interception at five zenith angles, from which LAI is computed using a model of radiative transfer vegetative canopies.
    

After the ground data collection, EOLAB provide ground-based high resolution maps according to CEOS LPV best practices for validate low and medium resolution products. It consists on a regression method and the selection of the optimal band combination applying empirical functions. We also generate the product Quality Flag by using a convex hull test, providing the level of confidence on the physical values. The mean values and standard deviation are extracted over the 3km x 3km area of the validation sites. They are exploited by the Copernicus Global Land service to assess the quality of the LAI, FAPAR, FCover products derived at 1km and 300m from SPOT/VGT and PROBA-V sensors data.

HR Ground Based FAPAR Map (20kmx20km) over Albufera  for mid of July, 2014.

HR Ground Based FAPAR Map (20kmx20km) over Albufera, Valencia (Spain)  for mid of July, 2014.

 

From 2013, EOLAB is responsible for field data collection in the FP7 ImagineS project, directly participating in filed campaigns, or in collaboration with different groups.  66 field campaigns have been conducted over 23 cropland sites during the period from 2013 to 2016. More than 15.000 hemispheric photos have been taken and processed to generate about 160 ground high resolution reference maps. ImagineS makes available the ground measurements of LAI, FAPAR, and FCover collected over demonstration sites and the resulting high resolution maps.

 

Now, the values of LAI, FAPAR and FCover averaged over 3kmx3km area are gathered in a single file. They are suitable for the accuracy assessment of the kilometric satelite-derived products like the ones delivered by the Copernicus Global Land service. They are also compliant with the OLIVE validation tool.