Evaluation of maize growth by ground based multi-spectral image

In order to evaluate growth status of maize automatically and accurately, a multi-spectral image camera was used to collect ground-based images of maize canopy in the field. The average gray value (G_IA, R_IA and NIR_IA) and the vegetation indices (DVI, RVI, NDVI, et al.) widely used in remote sensing were selected as the parameters for maize growth monitoring. The parameters were obtained based on image processing including image preprocessing, canopy segmentation and parameter calculation. After analyzing the correlation between each image parameter and chlorophyll content of maize leaf at the shooting stage, a new vegetation index, combination of normalized difference vegetation index (CNDVI), was developed and a positive correlation was observed between CNDVI and the chlorophyll content. The values of correlation coefficient were 0.63 and 0.60 under high and normal nitrogen treatment respectively. CNDVI performed great potential to estimate the chlorophyll content of maize.