FEATURES OF FULL SPECTRAL IMAGING

 

This page contains a comparison of a traditional optical remote sensing system, such as LANDSAT, with the proposed Full Spectral Imaging´┐Ż System which might replace LANDSAT.

 Traditional System

Full Spectral Imaging System

General

 

Transmits every byte acquired

Transmits all information acquired 

Measures top of-the-atmosphere spectral radiance

Measures at-target spectral reflectance 

Instrument

 

Utilizes light only in specific bands

Captures and uses all light 

Individual bandpass calibration required

Full spectral response calibration required 

Beamsplitters for VIS, SWIR, IR band separation

Separate focal planes for VIS, SWIR, IR band separation 

Single large focal planes

Multiple small focal planes 

External reference pointing stabilization system

Earth imaging referenced pointing stabilization system 

Post processing correction for Earth rotation

Yaw and roll correction for Earth rotation compensation 

Post processing geolocation

Real-time geolocation (associated with stabilization) 

Smear reduction by limited exposure time

Forward motion compensation for smear reduction 

On-board radiometric calibration system

No on-board radiometric calibration system 

On-Board Processing

 

Generates data as bytes per band

Generates data as spectral curves or features 

Linear analog-to-digital conversion

Non-linear (square root) analog-to-digital conversion 

Gain switch or multiple gains needed for full dynamic range

Larger dynamic range, Gain switch not needed 

Cloud mask or filter needed to reduce data rate

Clouds (featureless regions) automatically reduce data rate 

Ground uplinks required for operational mode control

Operational modes based on spectral signatures 

"Flat fielding" done on ground

"Flat fielding" done after A/D conversion (may be done on sensor chip) 

"Flat" spectral response

Blue scattered light compensation (K.M.) 

Data Transmission

 

All raw data acquired by instrument is transmitted

All information acquired by instrument is transmitted 

Fixed data volume per area covered

Data volume dependent on information in scene 

Bytes per band

Spectral curve coefficients or
3D Hyperspectral Cube Real-Time compression 

Individual scans - no compression

Full scenes - lossless or lossy compression 

Store and dump to near-polar receiving stations

Continuous direct broadcast 

Data Storage

 

Fixed data volume "scenes"

Data volume dependent on "scene" information content 

Bytes per spectral histogram

Spectral curve coefficients (or other curve representation) 

Bytes per pixel or per scan

Full scene compressed data (various optional compression schemes) 

Centralized processing and storage

Distributed reception, processing, and storage 

Data Utilization

 

Modeling used to retrieve at-target reflectance

Empirical algorithms used to retrieve at-target reflectance 

Data ordered from central facility

Data available via peer-to-peer network 


 

This page was last modified on June 30, 2014

 

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