PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping)

The PRISM is a panchromatic radiometer with 2.5 m spatial resolution at nadir. Its extracted data will provide a highly accurate Digital Surface Model (DSM). It has three independent optical systems for viewing nadir, forward and backward, producing a stereoscopic image along the satellite track.

Each telescope consists of three mirrors and several detector CCD, in which at the nadir-viewing telescope covers a width of 70Km, while the other two cover 35Km each.

The telescopes forward and backward are inclined + 24 and -24 degrees from nadir to realize a base-to-height ratio of 1.0, ideal for stereoscopy. PRISM's wide Field of Vision (FOV) provides three fully overlapped stereo (triplet) images of a 35Km width without mechanical scanning or yaw steering of the satellite.

Sensor Characteristics Number of Bands 1 (Panchromatic) Wavelength 0.52 to 0.77 micrometers Number of Optics 3 (Nadir; Forward; Backward) Base-to-Height ratio 1.0 (between Forward and Backward view) Spatial Resolution 2.5m (at Nadir) Swath Width 70km (Nadir only) / 35km (Triplet mode) S/N >70 MTF >0.2 Number of Detectors 28000 / band (Swath Width 70km) 14000 / band (Swath Width 35km) Pointing Angle -1.5 to +1.5 degrees (Triplet Mode, Cross-track direction) Bit Length 8 bits                 Note: PRISM cannot observe areas beyond 82 degrees south and north latitude.

Observation Modes