Abstract
RASAT, the second remote sensing satellite of Turkey, was designed and assembled, and also is being operated by TÜBİTAK Uzay (Space) Technologies Research Institute (Ankara). RASAT images in various levels are available free-of-charge via Gezgin portal for Turkish citizens. In this paper, the images in panchromatic (7.5 m GSD) and RGB (15 m GSD) bands in various levels were investigated with respect to its geometric and radiometric characteristics. The first geometric analysis is the estimation of the effective GSD as less than 1 pixel for radiometrically processed level (L1R) of both panchromatic and RGB images. Secondly, 2D georeferencing accuracy is estimated by various non-physical transformation models (similarity, 2D affine, polynomial, affine projection, projective, DLT and GCP based RFM) reaching sub-pixel accuracy using minimum 39 and maximum 52 GCPs. The radiometric characteristics are also investigated for 8 bits, estimating SNR between 21.8-42.2, and noise 0.0-3.5 for panchromatic and MS images for L1R when the sea is masked to obtain the results for land areas. The analysis show that RASAT images satisfies requirements for various applications. The research is carried out in Zonguldak test site which is mountainous and partly covered by dense forest and urban areas.
Highlights
1.1 RASAT MissionFollowing the first experience with Bilsat mission, RASAT is the second remote sensing satellite of Turkey, launched in August 17, 2011
This study is focused on the investigation of geometric and radiometric evaluation of RASAT images in various levels, covering Zonguldak test site (Turkey)
The images are acquired in 8 bits (256 grey values), and the histograms covers most part of grey scale (Figure 2)
Summary
Following the first experience with Bilsat mission, RASAT is the second remote sensing satellite of Turkey, launched in August 17, 2011. RASAT was designed and assembled with national experience in TÜBİTAK (The Scientific and Technological Research Council of Turkey) Space (Uzay) Technologies Research Institute, funded by Ministry of Development. Sun-synchronised 98.1° ~700 km 98.8 min 10.30 (local time) 93 kg 7.5 m 15 m 8 bit 2.5 days Pan: 0.42-0.73 μm Red: 0.58-0.73 μm Green: 0.55-0.58 μm Blue: 0.42-0.55 μm. Comparing with the previous non-operational satellite, Bilsat, RASAT has higher radiometric and geometric resolution. GÖKTÜRK-2 has higher resolution in all resolutions except temporal one
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