The bidirectional reflectance factor has been widely used and the lack of care to obtain the index can provide substantial amendments thereto mainly due to changes in acquisition geometry. This study investigated the anisotropy of Axonopus Compressus grassy canopy, frequently used as a permanent pasture, vegetation cover and lawn on humid soils with low fertility, and investigates its impact on the generation of indices commonly used as indices composed of ratios between red and near infra-red (NIR) bands like the Normalized Difference Vegetation Index (NDVI). For such an experiment was conducted in the LARAD laboratory by changing the view angles between nadir, 10, 20 and 30° opposite of the lighting and 10, 20 and 30° likewise lighting. Data were calibrated with a standard board by the spectral calibration factor (K_λ) and the anisotropy was calculated by Anisotropy Factor (ANIF), the interference of anisotropy in the band ratios was investigated by simulating the NDVI index by RED and NIR response bands of the MSI/Sentinel-2A and OLI/Landsat-8 sensors to each view angle. Was found that anisotropy of A. Compressus grassy spectrally varies for each view angle and it caused significant differences in simulated NDVI indices for MSI/Sentinel-2A and OLI/Landsat-8 sensors, reaching 15% and 53% respectively.