Maize field production shows spatial variability during vegetative crop growth that could be used to prescribe nitrogen variable rates. The use of portable sensors mounted on high-clearance applicators is well documented, however new UAS vehicle equipped with high resolution digital cameras could be used to determine crop spatial variability with the advantage of survey extensive field areas. To our knowledge, comparisons between vegetation indices obtained by a modified digital camera and GreenSeeker or hyperspectral measurements are unknown. The aims of this study were to compare vegetation indices (VI) obtained with a modified digital camera versus SPAD, VI obtained with a GreenSeeker and a hyperspectral sensor, and to study the relationship of VI with crop variables related to N status in maize. Selected treatments, ranged from 0 and 276 kgN ha^-1, were used to determine biomass, SPAD and sensors readings with a GreenSeeker and Ocean Optics USB 4000. The UAS was equipped with a digital camera modified by the extraction of the internal near-infrared blocking filter and the inclusion of a visible light-blocking filter.  Crop measurements were made at V6 and V10 growth stages and photograph were obtained with two ground spatial resolution. Crop variables at V10 were related with VI determined with commercial sensors and with aerial photograph. The highest sensitivity to detect biomass and LAI changes was observed for VI calculated from an uncorrected high spatial resolution aerial photograph obtained with a modified RGB camera.