The AS7265x Chipset as an Alternative Low-Cost Multispectral Sensor for Agriculture Applications Based on NDVI

Abstract

Recently, new low-cost multispectral sensors have been commercialized, paving the way for a large number of new agricultural applications (fertilization, grass cover, etc.), particularly for small farms. However, such sensors have never been tested for agricultural applications taking into account practical constraints (external environment, etc.). This study proposes to investigate the potentialities of the “AS7265x” chipset that presents a real interest for a wide range of applications in agriculture due to 18 spectral bands available. The first study involved the testing of three sensors in laboratory to assess the accuracy of the different spectral bands as well as the reproducibility of the measurements from one sensor to another but not presented here. In a second step, the work aimed at testing the potential of the sensor on real fields with two applications in proxy-detection to estimate the percentage of weeds over soil and the vine vigor. These field experiments focused on NDVI that is a vegetation index widely used in precision agriculture for proxy-sensing. Results show that although accurate, the sensors present some different bias for each wave bands and each sensor. These drawbacks require each sensor to be specifically calibrated before use which may limit their dissemination in agriculture. Once the sensor measurements are normalized, the NDVI values are consistent compared to the reference values given by the Greenseeker (R² = 0.87 for NDVI < 0.75). Hence, the accuracy obtained was sufficient to differentiate the levels of grass cover and the differences in vegetative expression of the vine induced by local environmental effects.