4 research outputs found
Spatio-Temporal Assessment of Tuz Gölü, Turkey as a Potential Radiometric Vicarious Calibration Site
No full textThe paper provides an assessment of Tuz Gölü, a site in Turkey proposed for the radiometric vicarious calibration of satellite sensors, in terms of its spatial homogeneity as expressed in visible and near-infrared (VNIR) wavelengths over a 25-year period (1984–2009). By combining the coefficient of variation (CV) and Getis statistic (Gi*), a spatially homogenous and temporally stable area at least 720 m × 330 m in size was identified. Analysis of mid-summer Landsat Thematic Mapper (TM) images acquired over the period 1984–2009 showed that the hemispherical-directional reflectance factor of this area had a spatial variability, as defined by the CV, in the range of 0.99% to 3.99% in Landsat TM bands 2–4. This is comparable with the reported variability of other test sites around the world, but this is the first time an area has been shown to have this degree of homogeneity over such a long period of time
ÇOBAN: Design of Multi-Spectral Opto-Electronic Satellite Camera System
No full textCOBAN (an abbreviation for "multi-spectral camera" in Turkish) is a Multi-spectral Earth observing camera system developed for BiLSAT, a 129 kg micro-satellite, which was launched into a 686 km sun-synchronous orbit in 27 September 2003. COBAN is one of the two Turkish R&D payloads hosted by BiLSAT in addition to the two primary imager payloads (a 4 band multi-spectral 26 m Ground Sampling Distance (GSD) imager and a 12 m GSD panchromatic imager). The technical specification of COBAN can be summarized as follows: Number of spectral bands: 8. Ground Sampling Distance: 12 meter. Image size (in pixels): 640 x 480 (KODAK KAI-0311 CCD) Wavelengths of the bands: 375-425 nm, 410-490 nm, 460-540 nm, 510-590 nm, 560-640 nm, 610-690 nm, 660-740 nm, 850-1000 nm Aimed primarily as a tool for improving the capabilities for instrument design for space, COBAN successfully performed in space. However, the most important outcome has been the lessons learned from mistakes during design, manufacturing and testing, that will hopefully help us avoiding serious failures in future missions
An assessment model and implementation of stereo image quality
No full textIn the past decade, many display hardware manufacturers have initiated research into the construction of stereo display devices. Currently, the use of such displays is limited to the computer-aided design; research, military and medical applications. However, it is anticipated that as display hardware becomes cheaper, gaming companies and desktop application software developers will realise the potential of using stereo to provide more realistic user experiences. To provide realistic stereo user experience it is necessary to utilise good quality stereo images in addition to suitable hardware. The growth of the Internet has resulted in an increase in the availability of stereo images. However, most have been captured using uncontrolled procedures and have questionable quality. The quality of stereo images is important since the viewing of poor quality stereo images can result in adverse viewing effects. A formal definition of stereo quality has not been achieved in current day research. This means that the factors which cause a stereo image to be perceived as poor quality have not been defined nor is a system available to detect its occurrence. This thesis attempts to address this problem by postulating a definition of stereo image quality based on detecting level of excess disparity levels, intensity differences and the occurrence of frame cancellation. An implementation system able to detect these identified factors is discussed and formulated. The developed system is utilised to test 14 stereo images of varying quality levels. The results of these tests are reported and are used to evaluated and refine the system. Using this image analysis, benchmarks for natural intensity difference in images, changes due to JPEG compression and comparisons with generated and ground truth disparity maps are formulated. Additionally, a
