Papers by Agus Kristijono
The surface change detection related to landscape disturbance and suspected water table variation... more The surface change detection related to landscape disturbance and suspected water table variation in peatland region were assessed based on Fine Beam Dual-polarization (FBD) ALOS-PALSAR data. Peat domes area of Kampar Peninsula of Sumatra Island in Riau province was selected as study area to assess the ability of multi temporal composite of FBD data for detecting the dynamic of landscape disturbance and interferometric technique for detecting surface changes associated with suspected water table dynamic of peat domes. It was found that HV (Horizontal-Vertical polarization) and HV-HH Normalized Difference gave the best results for detecting dynamics of landscape disturbance. For interferogram derivation, HH polarization data give less noise compare to that of HV polarization data. In addition, a combination of 2-pass DInSAR with post-processed spatial filter technique was proven useful to detect and to analyse vertical surface changes.
As one of major tankers routes in Indonesia, Malacca Strait is potentially prone to oil spill pol... more As one of major tankers routes in Indonesia, Malacca Strait is potentially prone to oil spill pollution. SAR image data is used to detect oil slick on sea surface, because of its capability for large scale of sea monitoring, and to solve clouds covering problem in Indonesia. Oil slick is visible on SAR images as dark patches, because it decreases the radar backscatter on sea surface, which is explained by Bragg scattering theory. This project proposes the procedure for auto segmentation of oil slick in SAR image data. To reduce speckle in SAR image, we used the Bayesian approach with maximum a posteori filter with assumption that radar reflectivity and speckle noise follow Gamma distribution. This technique is compared with another adaptive filter such as Lee and Frost filter, which shows the best result on reducing speckle on whole area with the lowest ratio of mean and standard deviation, reducing the bright fleck on oil area, and showing the continuity on oil slick and sea area, which is make easier in feature extraction of oil slick. Maximum entropy technique is used for feature extraction on oil slick segmentation with assumption that only two moments are to be determined i.e. oil slick and sea area. It shows the best performance on oil slick segmentation among the others co-occurrence techniques. The area classification between oil slick and look-alike area on low wind area is done based on these result.
Geophysical Research Letters, 2008
We elucidated ocean physical and biogeochemical responses to slow-moving Typhoon Meari using a ne... more We elucidated ocean physical and biogeochemical responses to slow-moving Typhoon Meari using a new method combining Argo float and satellite observations. Meari-driven upwelling brought colder, nutrient-rich deep water to the surface layer, causing sea surface cooling (3–6°C) and threefold enhancement of primary production (PP). Maximum surface cooling (and hence nutrient injection) and peak PP enhancement lagged Meari's passage by 1
Geophysical Research Letters, 2008
We elucidated ocean physical and biogeochemical responses to slow-moving Typhoon Meari using a ne... more We elucidated ocean physical and biogeochemical responses to slow-moving Typhoon Meari using a new method combining Argo float and satellite observations. Meari-driven upwelling brought colder, nutrient-rich deep water to the surface layer, causing sea surface cooling (3–6°C) and threefold enhancement of primary production (PP). Maximum surface cooling (and hence nutrient injection) and peak PP enhancement lagged Meari's passage by 1
Hyperspectral technology is considered as a new paradigm in remote sensing that attempts to impro... more Hyperspectral technology is considered as a new paradigm in remote sensing that attempts to improve the accuracy of spectral signatures readings by employing excessive number of channels in its sensor. BPPT has been assessing hyperspectral technology since mid-1990's by using various platforms and developing several application prototypes through Hyperspectral Assessment and Application Program (HAAP) involving a number of international partners. Some preliminary findings of the assessment indicate that hyperspectral composite images revealed in such an excellent clarity that supports visual interpretation with ease. In general, this paper is aimed to illustrate the current status of hyperspectral technology and to review about development program and its potential applications in Indonesia.
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Papers by Agus Kristijono