PRISM Panchromatic Remote-sensing Instrument for Stereo Mapping
The Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) is a panchromatic radiometer with 2.5m spatial resolution at nadir. Its extracted data will provide a highly accurate digital surface model (DSM).
PRISM has three independent optical systems for viewing nadir, forward and backward producing a stereoscopic image along the satellite's track. Each telescope consists of three mirrors and several CCD detectors for push-broom scanning. The nadir-viewing telescope covers a width of 70km; forward and backward telescopes cover 35km each.
The telescopes are installed on the sides of the optical bench with precise temperature control. Forward and backward telescopes are inclined +24 and -24 degrees from nadir to realize a base-to-height ratio of 1.0. PRISM's wide field of view (FOV) provides three fully overlapped stereo (triplet) images of a 35km width without mechanical scanning or yaw steering of the satellite. Without this wide FOV, forward, nadir, and backward images would not overlap each other due to the Earth's rotation.
|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)|
|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|
|Mode 1||Triplet observation mode using Forward, Nadir, and Backward views (Swath width is 35km)|
|Mode 2||Nadir (70km) + Backward (35km)|
|Mode 3||Nadir (70km)|
|Mode 4||Nadir (35km) + Forward (35km)|
|Mode 5||Nadir (35km) + Backward (35km)|
|Mode 6||Forward (35km) + Backward (35km)|
|Mode 7||Nadir (35km)|
|Mode 8||Forward (35km)|
|Mode 9||Backward (35km)|