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Improvement of Spatial Resolution with Staggered Arrays As Used in The Airborne Optical Sensor Ads40

Reulke, Ralf and Tempelmann, Udo and Stallmann, Dirk and Cramer, Michael and Haaler, Norbert (2004) Improvement of Spatial Resolution with Staggered Arrays As Used in The Airborne Optical Sensor Ads40. In: Proceedings of the XXth ISPRS Congress, IAPRS (part B). XXth ISPRS Congress, 2004-07-12 - 2004-07-23, Istanbul (Turkey). ISSN 1682-1750

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Abstract

Using pushbroom sensors onboard aircrafts or satellites requires, especially for photogrammetric applications, wide image swaths with a high geometric resolution. One approach to satisfy both demands is to use staggered line arrays, which are constructed from two identical CCD lines shifted against each other by half a picel in line direction. Practical applications of such arrays in remote sensing include SPOT, and in the commercial environment the Airborne Digital Sensor, or ADS40, from Leica Geosystems. Theoretically, the usefulness of staggered arrays depends from spatial reslution, which is defined by the total point spread function of the imaging system and Shannon's sampling theorem. Due to the two shifted sensor lines staggering results in a double number of sampling points perpendicular to the flight direction. In order to simultaneously double the sample number in the flight direction, the line readout rate, or integration time, has to produce half a pixel spacing on ground. Staggering in combination with a high-resolution optical system can be used to fulfil the sampling condition, which means that no spectral components above the critical spatial frequency 2/D are present. Theoretically, the resolution is as good for a non-staggered line with half pixel size D/2, but radiometric dynamics should be twice as high. In practice, the slightly different viewing angle of both lines of a staggered array can result in a deteration of image quality due to aircraft motion, attitude fluctuations or terrain undulation. Fulfilling the sampling condition further means that no aliasing occurs. This is essential for the image quality in quasiperiodical textured image areas and for photogrammetric sub-pixel accuracy. Furthermore, image restoration methods for enhancing the image quality can be applied more efficently. The panchromatic resolution of the ADS40 opties is optimised for image collection by a staggered array. This means, it transfers spatial frequencies of twice the Nyquist frequency of its 12k sensors. First experiments, which were carried out some years ago, indicated alrady a spatial resolution improvement by using image restitution the ADS 40 staggered 12k pairs. The results of the restitution algorithm, which is integrated in the ADS image processing flow, has now been analysed quantitatively. This paper presents the theory of high resolution image restitution from staggered lines and practical results with ADS40 high resolution panchromatic images and high resolution colour images, created by sharpening 12k colour images with high resolution pan-chromatic ones.

Document Type:Conference or Workshop Item (Paper)
Title:Improvement of Spatial Resolution with Staggered Arrays As Used in The Airborne Optical Sensor Ads40
Authors:
AuthorsInstitution or Email of Authors
Reulke, RalfUniversity of Stuttgart - Institute for Photogrammetry
Tempelmann, UdoLeica Geosystems GIS & Mapping GmbH
Stallmann, DirkUniversity of Stuttgart
Cramer, MichaelUniversity of Stuttgart - Institute for Photogrammetry
Haaler, NorbertUniversity of Stuttgart - Institute for Photogrammetry
Date:2004
Journal or Publication Title:Proceedings of the XXth ISPRS Congress
Refereed publication:No
In ISI Web of Science:No
Volume:IAPRS
ISSN:1682-1750
Status:Published
Keywords:photogrammetry, geometry, callibrtion, modeling, aerial sensor, digital, three-line, pushbroom
Event Title:XXth ISPRS Congress
Event Location:Istanbul (Turkey)
Event Type:international Conference
Event Dates:2004-07-12 - 2004-07-23
HGF - Research field:other
HGF - Program:other
HGF - Program Themes:other
DLR - Research area:no assignement
DLR - Program:no assignment
DLR - Research theme (Project):other
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Transport Research
Deposited By: elib DLR-Beauftragter
Deposited On:09 Dec 2005
Last Modified:12 Dec 2013 19:57

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