International cooperation and technology transfer

Fras, Mojca Kosmatin

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Monograph

Persistent identifier:: 856490555

Author:: Fras, Mojca Kosmatin

Title:: International cooperation and technology transfer

Sub title:: Ljubljana, Slovenia, February 2 - 5, 2000 : proceedings of the workshop

Scope:: VI, 163 Seiten

Year of publication:: 2000

Place of publication:: London

Publisher of the original:: RICS Books

Identifier (digital):: 856490555

Illustration:: Illustrationen, Diagramme

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: Digital Photogrammetric cameras: a new forward looking approach. P. Fricker, R. Sandau, P. Schreiber

Document type:: Monograph

Structure type:: Chapter

64 Fig. 5. SNR of a CCD-element at a saturation load of500,000 electrons and rms-noise of235 electrons. kpixcl Fig. 6. Effect of flat field illumination in the focal plane. One can clearly see the effect of the shading of the lens (at the edges the light intensity falls off to about 40%) and of the influence of the PRNU. The differences of sensitivity of CCDs are usually indicated in the datasheets as PRNU values in percent of the values of the videocurrent for the range far below saturation (mostly at 50% of U mt ). We will adhere to this definition here as well. Thus in the linear range of the CCD the fixed pattern noise of the pixel sensitivity can be expressed directly as a signal dependent noise, which is converted into a time dependent noise during transfer of the charge. PRNU PRNU o,.. = //.. = cr; 100% 100% (3) Depending on the PRNU of the CCD the signal to noise ratio results as: SNR = (4) 1 + PRNU 100% cr. Figure 7 shows the highest attainable SNR at full exploitation close to saturation (400,000 to 500,000 signal electrons) in relation to PRNU, based on the aforementioned parameters. Up to a PRNU value of 0.02% the SNR is determined exclusively by the photon noise of the signal, the rms noise of the CCD and the noise of the analogue channel. At 0.1% the PRNU influence becomes dominant. In the engineering model of LH Systems’ new airborne digital sensor, described in sections 6 and 7 below, the PRNU correction is done pixel-wise. Fig. 7. SNR in relation to PRNU assuming a thermal and electronic noise of S e [ = 235 rms-electrons and a signal electron counts of500 000 e~. Normally light fall-off of the lens system (approximately 30%) is corrected simultaneously with the PRNU correction. For the estimation or the PRNU correction, this fall-off has not been taken into account because it does not contribute directly to an increase of the SNR. It only contributes indirectly through the adaptation of the signal to the analogue channel. The correction of light fall-off of the lens does not restrict the SNR significantly. The efficiency of the correction can be seen in Figure 8, which shows imagery of the Reichstag, Berlin, taken with the engineering model of the LH Systems airborne digital sensor on 23 April 1999. The flying height was 3 km and the ground sample distance is 0.25 m. In the radiometrically zoomed- out image parts no noise can be seen.

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