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ANALYSIS OF SPOT-6 DATA FUSION USING GRAM-SCHMIDT SPECTRAL SHARPENING ON RURAL AREAS
No full textImage fusion is a process to generate higher spatial resolution multispectral images by fusion of lower resolution multispectral images and higher resolution panchromatic images. It is used to generate not only visually appealing images but also provide detailed images to support applications in remote sensing field, including rural area. The aim of this study was to evaluate the performance of SPOT-6 data fusion using Gram-Schmidt Spectral Sharpening (GS) method on rural areas. GS method was compared with Principle Component Spectral Sharpening (PC) method to evaluate the reliability of GS method. In this study, the performance of GS was presented based on multispectral and panchromatic of SPOT-6 images. The spatial resolution of the multispectral (MS) image was enhanced by merging the high resolution Panchromatic (Pan) image in GS method. The fused image of GS and PC were assessed visually and statistically. Relative Mean Difference (RMD), Relative Variation Difference (RVD), and Peak Signal to Noise Ratio (PSNR) Index were used to assess the fused image statistically. The test sites of rural areas were devided into four main areas i.e., whole area, rice field area, forest area, and settlement. Based on the results, the visual quality of the fused image using GS method was better than using PC method. The color of the fused image using GS was better and more natural than using PC. In the statistical assessment, the RMD results of both methods were similar. In the RVD results, GS method was better then PC method especially in band 1 and band 3. GS method was better than PC method in PSNR result for each test site. It was observed that the Gram-Schmidt method provides the best performance for each band and test site. Thus, GS was a robust method for SPOT-6 data fusion especially on rural areas
DOWNWELLING DIFFUSE ATTENUATION COEFFICIENTS FROM IN SITU MEASUREMENTS OF DIFFERENT WATER TYPES
No full textProcess of light reduction or loss (attenuation) by scattering and absorption is affected by solar zenith, time, depth, and seawater constituents. Downwelling diffuse attenuation coefficient (Kd) is important to understand for light penetration and biological processes in ocean ecosystem. It is, therefore, important to know the Kd value and its variability in ocean ecosystem. The objective of this study was to determine downwelling diffuse attenuation coefficients and its variability form in situ measurements of different water types. In situ downwelling irradiances (Ed) were measured using a submersible marine environmental radiometer instrument (MER) during a clear sky, calm water condition, and at the time range of 10:30 a.m. up to 14:00 p.m. local time in the northeastern Gulf of Mexico in April 2000. In general, Ed values decreases exponentially with depth. Ed at 380 nm exhibited the lowest attenuation (the most penetrative light), while Ed at 683 nm exhibited the highest attenuation (the most light loss at the top of water column). Overall, the Kd patterns tended to decrease from 380 nm to 490 nm (blue-green wavelength), and increase from 490 nm to 683 nm (green-red wavelength). Kd values in offshore region were relatively lower than in coastal region. Kd can be used to determine the depth of euphotic zone in offshore or teh case-1 water type and the depth of one optical depth (the water column depth where the ocean color satellite can possibly sense)
THE APPLICATION OF WAVELET ANALYSIS FOR INTERNAL WAVE DETECTION IN SAR AND OPTICAL IMAGES DATA OVER TSUSHIMA STRAIT
No full textOn this paper, wavelet analysis has been used for internal wave detection in ERS SAR and ASTER images data over Tsushima strait, southwest of Japan, during 1993-2004 period. Various wavelet transforms, such as Haar wavelet, Symlet wavelet, Coif wavelet, Daubechies wavelet, and Discreet Meyer wavelet, are tested comparably with different level of synthesize image on horizontal, diagonal, and vertical detail, and approximation to study the internal wave characteristic in image. Internal wave features were detected as elongated pattern in image with higher wavelet coefficient (>36) than sea surface (litlle than 10) on horizontal and vertical detail coefficient of image transforms at level 2-5. The decomposition image shows the tendency that the decomposition of internal wave feature using wavelet transform tends to follow the wavelet function. This may reduced the height of leading wave. Smoother result of internal wave shape can be formed using higher scale resolution of image and higher number of vanishing moments such as Daubechies waveletdb5, Symlet wavelet-sym5, and Discrete Meyer wavelet. The compactly supported wavelet function with orthogonal basis with scale function and FIR filter, such as discrete Meyer function is proposed for smoothness of feature, space save coding, and to avoid depashing in image. So far, the detection processes were performed well on the internal waves data that occurred at north coast off Kitakyushu and NW/W/SW/E coast off Tsushima Island on June to September period whose lengths were detected between 6-28 km and wavelength between 120m-1.28km. The directions of internal wave propagation were varied between NW-SW at eastern channel and N-SW at western channel of Tsushima Strait
STUDY OF SUSPENDED SEDIMENT DISTRIBUTION USING NUMERICAL MODEL AND SATELLITE DATA IN BENOA BAY-BALI, INDONESIA
No full textThe distribution of suspended sediment and its concentration within Benoa bay was calculated by a numerical model and utilization of satellite data. A two-dimensional coupled hydrodynamic-transport model for the distribution characteristics of suspended sediment within the bay is presented here. Three-river discharges and sewerage installation outlets were used as source points of the suspended sediment. The model result showing the distribution of suspended sediment pattern follows the tidal level dynamic. It is concerned to the current pattern generated by tidal. The ALOS/AVNIR-2 satellite data also have good capability to investigate the suspended sediment distribution in coastal area. By using visible channels and developed regression of Digital Number (DNs) of AVNIR-2 data and observation data, the distribution of suspended sediment in Benoa bay was generated. Numerical model and satellite data quantitatively have the same tendency, but slightly different value. It is because of the differences in pollutant sources point
COMPARISON RESULT OF DEM GENERATED FROM ASTER STEREO DATA AND SRTM
No full textThis paper explains a method to generated DEM (Digital Elevation Model) from ASTER (Advanced Spaceborn Thermal Emission and Reflection Radiometer) stereo data and evaluates the generation of ASTER DEM and SRTM (Shuttle Radar Topography Mission) DEM with 90 m spatial resolution. ASTER DEM is generated from 3n (nadir looking) and 3b (backward looking) level 1b, with 10 ground control points (XYZ coordinate)derived from ASTER RGB 321 geometric-corrected image and SRTM DEM. Almost all tie points are collected automatically and several tie points is added manually. The triangulation and DEM extraction process are made automatically using ERDAS Imagine Software. DEM evaluation is carried out by comparing between ASTER DEM and SRTM DEM in the height distribution of vertical and horizontal transect lines and the height value of the whole DEM image. The process is continued by analyzing the height differences between ASTER DEM and SRTM DEM. The results shows thatASTER DEM has 15 m spatial resolution with height differnces less than 30 m for about 67 percent of total area, and absolute mean error is 27 m (compared with SRTM DEM) This absolute mean error is large enough, because the GCPs (Ground Control Point) used in this study are only in a small amount and most of study area is in the high terrain area (mountainous area) with dense vegetation coverage
Cosmic Ray Intensity Analysis Based on the Earth’s Latitude and Hemisphere
No full textThe interaction between cosmic rays and solar activity has been extensively investigated,particularly in relation to how solar phenomena modulate cosmic ray intensity inthe heliosphere. The strength of cosmic rays absorbed by the Earth’s hemisphere is notuniform across the Northern Hemisphere (NH) and Southern Hemisphere (SH). This studywill include an investigation of cosmic ray intensity as recorded at various latitudes andhemispheres of the Earth. We employed nine cosmic ray stations in each NH and SH,separated into three types of latitudes: low, middle, and high. The method of percentagechange in cosmic ray intensity was used, which was evaluated during the HalloweenStorm phenomenon on October 29-30, 2003. The results showed that cosmic ray intensitydecreased more at high latitudes than at low latitudes in both hemispheres (NH and SH).Furthermore, the reduction in cosmic ray intensity observed in the NH was approximately1% greater than that observed in the SH. This can be attributed to the Rc value’s dependenceon latitude, variations in geomagnetic activity under different Interplanetary MagneticField (IMF) circumstances, and interplanetary space parameters such as the tilt of theHeliospheric Current Sheet (HCS)
PERANCANGAN AUTOPILOT LATERAL-DIREKSIONAL PESAWAT NIRAWAK LSU-05 (THE DESIGN OF THE LATERAL-DIRECTIONAL AUTOPILOT FOR THE LSU-05 UNMANNED AERIAL VEHICLE)
No full textAutopilot pada pesawat dikembangkan berdasarkan pada modus gerak pesawat yaitu modus gerak longitudinal dan lateral-directional. Pada makalah ini, dirancang autopilot pada modus gerak lateral-directional untuk pesawat LSU-05. Autopilot dirancang pada range kecepatan operasi pesawat yaitu 15 m/dtk, 20 m/dtk, 25 m/dtk, dan 30 m/dtk dengan ketinggian 1000 m. Autopilot yang dirancang adalah Roll Attitude Hold, Heading Hold dan Waypoint Following. Autopilot dirancang berdasarkan model linier dalam bentuk state-space. Pengendali yang digunakan adalah pengendali Proportional-Integral-Derivative (PID). Hasil simulasi menunjukan nilai overshoot/undershoot tidak melebihi 5% dan settling time kurang dari 30 detik jika diberikan perintah step
ANALISIS KETINGGIAN ORBIT SATELIT LAPAN-TUBSAT SETELAH SATU TAHUN BEROPERASI
No full textSatelit LAPAN-TUBSAT merupakan salah satu program unggulan pengembangan satelit eksperimen berskala nasional yang dilakukan oleh LAPAN. Sejak diluncurkan tanggal 10 Januari 2007, kini telah mengorbit selama 1 tahun lamanya. Pengontrolan data status kesehatan satelit (house keeping data) terus dilakukan setiap harinya dengan mengamati semua komponen utama satelit seperti batery, solar panel, star sensor, camera sony dan kappa, gyroscope, sistem komunikasi payload S band 2220 MHz dan TTC UHF 437,325 MHz. Dari data TTC yang diperoleh ternyata setelah satu tahun mengorbit, telah terjadi perubahan ketinggian orbit satelit LAPAN-TUBSAT dari ketinggian orbitnya saat pertama diluncurkan. Peluruhan ini diakibatkan oleh pengaruh kondisi lapisan teratas atmosfir. Dalam tulisan ini akan dijelaskan fenomena peluruhan orbit satelit LAPAN-TUBSAT setelah satu tahun operasi dengan menganalisis data keplerian atau 2-line element yang digunakan
APLIKASI PERANGKAT LUNAK SISTEM AKUISISI KECEPATAN REACTION WHEEL (SOFTWARE APPLICATION OF REACTION WHEEL SPEED ACQUISITION SYSTEM)
No full textKegiatan alih teknologi melalui reverse engineering merupakan upaya yang dilakukan oleh negara berkembang dalam rangka memperkecil jarak ketimpangan dari negara maju dalam hal teknologi, termasuk teknologi satelit. Melakukan pengukuran dan akuisisi data dalam rangka mengurai informasi desain suatu komponen satelit adalah tahap pertama proses reverse engineering. Makalah ini melaporkan hasil penelitian mengenai pengembangan perangkat lunak sistem akuisisi data kecepatan wheel dari sebuah aktuator satelit yang disebut reaction wheel unit. Dalam aspek fase pengembangan satelit, sistem akuisisi data ini dapat digunakan sebagai perangkat pengujian untuk verifikasi di tingkat komponen. Data kecepatan wheel, yang diperoleh dari eksperimen yang dilakukan, ditampilkan dengan grafik respon transien. Berdasarkan analisis atas data tersebut, sistem akusisi data yang dikembangkan menjanjikan untuk digunakan dalam rangka pengukuran karakteristik dinamik reaction wheel sebagai upaya mengurai informasi desainnya. Selain itu, analisis yang telah dilakukan merepresentasikan bagian dasar dari tahap verifikasi di tingkat komponen. Hal ini menunjukkan bahwa sistem akusisi data ini menjanjikan untuk digunakan sebagai perangkat pengujian di dalam fase pengembangan satelit
TINJAUAN ASPEK KESELAMATAN UJI STATIK ROKET DENGAN PROPELAN KEROSEN–ASAM NITRAT TERHADAP MANUSIA DAN LINGKUNGAN
No full textRoket propelan cair memiliki beberapa kelebihan bila dibandingkan dengan roket propelan padat. Jumlah dan perbandingan bahan bakar terhadap oksidator dapat diatur untuk menghasilkan gaya dorong yang diinginkan. Salah satu propelan yang digunakan saat ini adalah pasangan kerosen dan asam nitrat. Namun, penggunaan propelan ini memunculkan masalah akibat karakter propelannya. Asam nitrat adalah cairan yang sangat korosif dan dapat menyebabkan efek yang serius terhadap tubuh manusia. Tinjauan terhadap keselamatan dalam uji statik roket cair telah dilakukan. Pada uji statik, kerosen dan asam nitrat akan diinjeksi ke dalam ruang bakar dan bereaksi sehingga menghasilkan gas bertekanan dan bertemperatur tinggi yang kemudian disemburkan melalui nosel untuk menghasilkan gaya dorong. Dari hasil kajian, daerah pengujian dibagi menjadi 5 zona. Zona 1, daerah yang paling berbahaya berjarak 0 – 3 m, dan zona 2, 3 – 40 m, adalah daerah yang masih dipengaruhi oleh gas-gas berbahaya. Pengamatan langsung dapat dilakukan pada jarak 50 m dengan perlindungan bangunan