Each satellite carries a charge-coupled device (CCD) sensor which contains two identical cameras (CCD1 and CCD2). Detailed technical specifications of the cameras can be found in 3. The CCD sensor has a pushbroom scanning mechanism similar to a high-resolution visible sensor (HRV) on the Satellite Pour l’Observation de la Terre (SPOT) platform. In order to provide imaging data over large areas, CCD1 and CCD2 offer an oblique viewing capability, with the view angle tilting relative to the vertical, as shown in Fig. 1. The field of view (FOV) of CCD1 and CCD2 is relatively large, about 30 deg. As a result, the nominal variation of the view zenith angle for a given point on the Earth’s surface per overpass is from to , where a minus sign indicates view angles in the forward scatter direction and a plus sign indicates view angles in the backscatter direction. Taking into account the effect of the Earth’s surface curvature, view zenith angles of up to from the nadir have been sampled in this study. Observations from a single orbit were acquired at different viewing geometries relative to the source of illumination (the sun); some measurements were taken in the forward direction and some in the backward direction. For one optical satellite, the revisit cycle of the multispectrum CCD camera is 96 h. Because the HJ-1A and HJ-1B satellites are in the same orbit with a phase difference of 180 deg, the repeat cycle of the CCD sensor is reduced to . Therefore, the HJ-1A and HJ-1B satellite sensors have the capability of sampling the hemispherical-directional reflectance factor (HDRF) over a wide range of view zenith angle in a short time period in four spectral bands from 0.43 to 0.90 μm, which makes them attractive for detecting land cover changes, vegetation dynamics monitoring, and primary production estimates.