• Proceedings of the KSRS Conference
• /
• 1999.11a
• /
• pp.310-315
• /
• 1999

We extracted narrow open water streams from JERS-1 SAR images of the Amazon rain forest. The extracted range of these streams were almost comparable to a high level extraction of the same streams from near-IR images of JERS-1 VNIR data notwithstanding that these features in SAR images show the strong dependence of the observation angle. Large water bodies are relatively easy to extract from JERS-1 SAR images, as they tend to appear as very dark areas; but streams whose width is nearly equal to or less than the spatial resolution no longer appear as very dark features. By using strong scatterers distributed sparsely along the radar facing sides of the streams, we can successfully estimate approximate ranges of waterways and then extract relatively dark line-like features within these ranges.

• Korean Journal of Remote Sensing
• /
• v.14 no.1
• /
• pp.95-101
• /
• 1998

This paper describes an algorithm which was developed for removing along-track and across-track striping effect shown in JERS-1 OPS/VNIR images. A statistical algorithm was implemented based on the mean brightness value of each along-track and across-track line. Different from any filtering techniques in either spatial or frequency domain, the developed algorithm does not change the radiometric characteristics of image pixels. The algorithm will be inserted to the JERS-1 OPS image data processing chain in the Satellite Technology Research Center direct receiving station.

• Economic and Environmental Geology
• /
• v.38 no.4 s.173
• /
• pp.381-394
• /
• 2005

Mokpo city is a coastal city located at the south western coast of the Korean Peninsula. Large regions within Mokpo are subjected to significant subsidence because about $70\%$ of the city area is a reclaimed land from the sea. Although no confidential quantitative measurements are available up to the present, the subsidence rate is as much as several cm per year. In this study, we aimed to estimate the subsidence rate over Mokpo city by using twenty-six JERS-1 SAR dataset from September 1992 to October 1998. Several tens of differential interferograms were processed from JERS-1 dataset and STRM 3-arc DEM. The results indicate continuous subsidence in Dongmyung-dong, Hadang-dong and Wonsan-dong in city, and the subsidence velocity reach over 4 cm/yr in the most highly sinking area. For facilitating the analysis of time-varying surface change, we also carried out an interferometric SAR time series analysis using permanent scatterer and consequently determined space-time maps of surface deformation at each acquisition time of JERS- 1 SAR.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.2 no.1
• /
• pp.73-83
• /
• 1999

The land use/cover information, which is periodically obtained from satellite imagery, can be effectively applied to change detection in rapidly changing urban areas. Also it can be used not only as base maps for spatial database in urban information system but as decision-making data for desired urban planning and development direction. In this study, we carried out both unsupervised and supervised classification on land use from Landsat TM and JERS-1 OPS data, which were collected respectively in 1991 and 1997, covering Kumi City and then detected land use changes.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1073-1075
• /
• 2003

We apply the radar interferometry technique to JERS-1 SAR data sets for detection of slow surface deformation occurred in Mt. Baekdu for a 6-year period (from 1992 to 1998). A series of interferograms has been constructed, and they indicated slow uplift deformation around the volcano. However, it is not conclusive because most interferometric fringes correlate with topographic elevation. It is necessary to remove trophospheric effects in the future works.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.5 no.1
• /
• pp.27-37
• /
• 2002

The classification accuracy of land cover has been considered as one of the major issues to estimate pollution loads generated from diffuse landuse patterns in a watershed. This research aimed to assess the effects of the acquisition methods and sampling size of training reference data on the classification accuracy of land cover using an imagery acquired by optical sensor(OPS) on JERS-1. Two kinds of data acquisition methods were considered to prepare training data. The first was to assign a certain land cover type to a specific pixel based on the researchers subjective discriminating capacity about current land use and the second was attributed to an aerial photograph incorporated with digital maps with GIS. Three different sizes of samples, 0.3%, 0.5%, and 1.0% of all pixels, were applied to examine the consistency of the classified land cover with the training data of corresponding pixels. Maximum likelihood scheme was applied to classify the land use patterns of JERS-1 imagery. Classification run applying an aerial photograph achieved 18 % higher consistency with the training data than the run applying the researchers subjective discriminating capacity. Regarding the sample size, it was proposed that the size of training area should be selected at least over 1% of all of the pixels in the study area in order to obtain the accuracy with 95% for JERS-1 satellite imagery on a typical small-to-medium-size urbanized area.

• Economic and Environmental Geology
• /
• v.37 no.5
• /
• pp.509-519
• /
• 2004

The ground subsidence that occurred in the abandoned coal mining area, Gaeun, Korea, was observed using 25 JERS-1 SAR interferograms from November 1992 to October 1998. We carried out measurements on a subset of image pixels corresponding to point-wise stable reflectors(PS: permanent scatterer) by exploiting a long temporal series of interferometric phases and compared it with the distribution map of in situ examined crack level. PSs could be identified by means of amplitude dispersion index and coherence of the interferograms and the density of PS was much higher in an urban area than in a mountainous region. The measured subsidence rate represented the average velocity in a period of image acquisition and excluded complex nonlinear displacements such as an abrupt collapse. The mean line-of-sight velocity in the study area is 0.19cm/yr and the estimation error is 0.18cm/yr. The center of the abandoned Gaeun coal mine(0.49cm/yr) and the area opposite Gaeun station(1.66cm/yr) were observed as the most highly subsiding areas.

• Proceedings of the KSRS Conference
• /
• 2002.10a
• /
• pp.454-459
• /
• 2002

We have developed a new method to visualize river networks in tropical rain forests from JERS-1 SAR images. This method compresses river information in an original SAR image to a small image displaying wide rivers as dark objects in real size and narrower rivers as bright objects showing brightness level as an indicator of the discharge. We applied this method to 476 images of Amazon forests, 13 observations for path 415 data and 11 observations for path 416 data between 1993 and 1997. We confirmed that a change observed in a preliminary experiment was certainly a part of seasonal changes. The changes roughly correspond to the monthly precipitation changes. Through a simple digital analysis although qualitative, we also detected subtle but consistent regional differences among minor tributaries that belong to a major tributary basin.

• Korean Journal of Remote Sensing
• /
• v.10 no.2
• /
• pp.161-170
• /
• 1994

The JERS-1 is an Earth Resources Satellite launched by NASDA (Natinal Space Development Agency) of Japan, in February in 1992 and has two sensors; SAR(L-Band Synthetic Aperture Radar) and OPS (SWIR and VNIR radiometers). In this research note, the basic properties and data characteristics of the SAR data are summarized based on the observations made on the data sets received for the Nahanni Canadian test site, Northwest Territories. The JERS-1 SAR data quality. including the spatial resolution of the data, is, in general, excellent for most geological applications.

• Korean Journal of Remote Sensing
• /
• v.21 no.4
• /
• pp.287-302
• /
• 2005

Digital Elevation Models (DEMs) were generated by ERS-l/2 and JERS-1 SAR interferometry in Daejon area, Korea. The quality of the DEM's was evaluated by the Ground Control Points (GCPs) in city area where GCPs were determined by GPS surveys, while in the mountain area with no GCPs, a 1:25,000 digital map was used. In order to minimize errors due to the inaccurate satellite orbit information and the phase unwrapping procedure, a Differential InSAR (DInSAR) was implemented in addition to the traditional InSAR analysis for DEM generation. In addition, DEMs from GTOPO30, SRTM-3, and 1:25,000 digital map were used for assessment the resolution of the DEM generated from DInSAR. 5-6 meters of elevation errors were found in the flat area regardless of the usage and the resolution of DEM, as a result of InSAR analyzing with a pair of ERS tandem and 6 pairs of JERS-1 interferograms. In the mountain area, however, DInSAR with DEMs from SRTM-3 and the digital map was found to be very effective to reduce errors due to phase unwrapping procedure. Also errors due to low signal-to-noise ratio of radar images and atmospheric effect were attenuated in the DEMs generated from the stacking of 6 pairs of JERS-1. SAR interferometry with multiple pairs of SAR interferogram with low resolution DEM can be effectively used to enhance the resolution of DEM in terms of data processing time and cost.