Showing papers by "Motoyuki Sato published in 2008"
TL;DR: This letter presents a tractable approach for the reconstruction of 3-D stereo buildings from two airborne PI-SAR images taken from opposite directions (at X-band with a spatial resolution of 1.5 m).
Abstract: Polarimetric synthetic aperture radar (SAR) images describe objects via polarization synthesis and present much richer information than monopolarized SAR images. Furthermore, multidirectional flights of polarimetric SAR can see 3-D stereo objects in different angles. The height and the location of the 3-D objects can be retrieved from the polarimetric SAR images in multidirectional flights. This letter presents a tractable approach for the reconstruction of 3-D stereo buildings from two airborne PI-SAR images taken from opposite directions (at X-band with a spatial resolution of 1.5 m).
13 citations
17 Oct 2008
TL;DR: In this article, a hand-held dual-sensor system for demining has been developed, which integrates ground-penetrating radar (GPR) and a metal detector.
Abstract: A hand-held dual-sensor system for demining has been developed. The system integrates ground-penetrating radar (GPR) and a metal detector. One of the features of the system is imaging capability. The system achieves the position information by tracking the sensor head. Thus synthetic aperture radar (SAR) processing can be applied and the performance can be significantly improved. The system was tested by real deminers in Croatia 2007. The trial results confirmed that false alarms (alarms from other than landmines) were significantly reduced by using GPR, meaning total demining operation can be accelerated. Them we started a half-year evaluation test of the system in quality-control (QC) test in Croatia in December 2007. This test will be conducted in various soil environmental conditions in Croatia.
12 citations
TL;DR: Both polarimetric calibration approaches can guarantee the further implementation of radar polarimetry techniques, and especially, the single-hole polarIMetric calibration will be very meaningful to practical applications.
Abstract: A fully polarimetric borehole radar system with four combinations of dipole and cylindrical slot antennas was developed to acquire fully polarimetric datasets in drilled boreholes. This system in conjunction with several radar polarimetry techniques has proved to be a good alternative to physical subsurface fracture characterization. Furthermore, such polarimetry techniques, namely Pauli decomposition, eigenvector-based decomposition, Durden–Freeman decomposition and polarimetric anisotropy parameter methods, can provide comparable performances in terms of fracture characterization and classification. Polarimetric calibration to determine a scattering matrix (Sinclare matrix) is the foremost procedure in the radar polarimetry processing chain. In this paper, we experimentally implement and evaluate two polarimetric calibration approaches, namely (1) cross-hole polarimetric calibration and (2) single-hole polarimetric calibration, utilizing fully polarimetric datasets acquired at a specific borehole test site. Both polarimetric calibration approaches can guarantee the further implementation of radar polarimetry techniques, and especially, the single-hole polarimetric calibration will be very meaningful to practical applications.
10 citations
TL;DR: In this article, the authors conducted a geophysical survey at the Akhmim archaeological site, the main objective of their survey is to locate additional buried structures for further excavation, and the results of the integrated interpretation show a number of buried features and a strong linear zone about 1 m wide that coincides with the suspected trend of a buried wall.
Abstract: Ground penetrating radar, electromagnetic terrain conductivity, and electric tomography have proven to be effective tools if they are combined together to investigate archeological sites. We have conducted a geophysical survey at the Akhmim archaeological site, the main objective of our survey is to locate additional buried structures for further excavation. Geophysical data were acquired in the area using the GEM-300 multi-frequency terrain conductivity profiler, the SIR 2000 ground penetrating radar, and the Syscal R2 resistivity meter systems. The results of the integrated interpretation show a number of buried features and a strong linear zone about 1 m wide that coincides with the suspected trend of a buried wall. There appears to be two parallel ridges of strong reflections on either side, indicating two parallel walls extended East-West and a room is identified at the bottom left corner of the site. Moreover, the interpretation results of some selected GPR and dipoledipole resistivity profiles adjacent to the open-air museum suggest the existence of a second statue of Ramses II to the right of the previously discovered statue which could still be buried in the sand.
6 citations
07 Jul 2008
TL;DR: L-band SAR has a enough ability to detect a flooding area in urban site over a flood test site in Chiba, Japan.
Abstract: We performed a Ground Based SAR (GB-SAR) and PiSAR simultaneous experiment over a flood test site. In this site, one prefab was constructed in a baseball field of a Nihon University in Chiba, Japan. The PiSAR observations were done for three days with different soil moisture condition of ~25%, ~50%, and 100%. Some GB-SAR experiments have been also done in two of three days and the scattering process are examined. Preliminary experiment with GB-SAR showed that L-band sigma0 from a double scattering of ground-wall is increased for a few dB, when a reflectivity of the ground is assumed to be 1. These increase are also confirmed in the test site for both PiSAR and GB-SAR. Furthermore, high resolution GB-SAR images show double and single bounce scattering from a metal bar behind the wooden board of the prefab. We conclude that L-band SAR has a enough ability to detect a flooding area in urban site.
6 citations
07 Jul 2008
TL;DR: ALIS can reconstruct buried land mine images in 3D space after data acquisition and it is found that the image reconstruction or migration processing drastically increases the quality of the image of the buried objects.
Abstract: More than 60 courtiers are still suffered from land mines. ALIS is a hand-held dual-sensor developed for humanitarian demining, which has been developed at Tohoku University, Japan since 2002. The dual-sensor ALIS is equipped with a metal detector and a GPR (Ground Penetrating Radar). A unique and novel sensor tracking system, which can record the GPR and Metal detector signal with their acquired locations, is equipped in ALIS. Due to its sensor location information, we can reconstruct buried land mine images in 3D space after data acquisition. IN addition, we found that the image reconstruction or migration processing drastically increases the quality of the image of the buried objects. ALIS evaluation test was conducted in Croatia in October 2007. Then a half-year evaluation test of ALIS in QC test in Croatia was held during December 2007 and April 2008. In this test, we could obtain fruitful experience in various soil and environmental conditions in Croatia.
5 citations
17 Oct 2008
TL;DR: A bistatic radar system for detection of buried objects, including buried land mines, and explosive material in a wall is developed and an effective signal processing by F-K filtering is proposed.
Abstract: We have developed a bistatic radar system for detection of buried objects. The targets include buried land mines, and explosive material in a wall. The system is composed of a fixed transmitting antenna and a small receiving antenna. The receiving antenna uses a passive optical electric field sensor. Due to its small size of the receiving sensor, the operation of the system is easy in various conditions. Then we propose an effective signal processing by F-K filtering. By suppressing the strong transmitting signal, we could obtain clear images of the buried objects. We think this radar system is useful in various security issues.
5 citations
03 Apr 2008
TL;DR: The research group at Tohoku University has developed a new hand-held land mine detection dual-sensor ALIS, equipped with a metal detector and a GPR, and it has a sensor tracking system, which makes possible to process the data afterwards, including migration.
Abstract: Since 2002, our research group at Tohoku University has developed a new hand-held land mine detection dual-sensor ALIS. ALIS is equipped with a metal detector and a GPR, and it has a sensor tracking system, which can record the GPR and Metal detector signal with its location. It makes possible to process the data afterwards, including migration. The migration processing drastically increases the quality of the image of the buried objects. ALIS evaluation test was conducted in Croatia in October 2007. Then after, we stared a half-year evaluation test of ALIS in QC test in Croatia in December 2007. This test will be conducted in various soil and environmental conditions in Croatia.
3 citations
02 Jun 2008
TL;DR: In this paper, a hand held dual sensor ALIS is proposed, which is a combination of a ground penetrating radar (GPR) sensor and a metal detector for detecting buried landmines.
Abstract: We are developing innovative sensor systems for humanitarian demining. A hand held dual sensor ALIS is one of them, which is a combination of a GPR (Ground Penetrating Radar) sensor and a metal detector. ALIS uses metal detector as a primary sensor for metal objects, and then use GPR for confirmation for burie dlansmines. With a wide frequency (1GHz-4GHz) operation of the system and sophisticated signal processing, ALIS can image buried landmine under strong clutter conditions. SAR signal processing is the msot important for clutter reduction. We have evaluated the ALIS system in some mine affected courtiers including Afghanistan, Croatia and Cambodia. ALIS evaluation test was conducted in Cambodia in 2006, where ALIS was operated by local deminers. They could show that ALIS can discriminate landmines and metal fragments.
2 citations
17 Oct 2008
TL;DR: The first applications of GPR was geological exploration such as salt and coal, which was started 1970s as mentioned in this paper, and many tests showed it is a good method to estimate the location of mineral resources.
Abstract: One of the first applications of GPR was geological exploration such as salt and coal, which was started 1970s. Many tests showed it is a good method to estimate the location of mineral resources. The GPR equipment at that time was quite simple, but in specific application, it was quite useful. We can find many salt deposits in north Germany. The salt deposits in natural geology are complete dry material and it is transparent for electromagnetic waves. Therefore maximum range by GPR reaches several hundred meter very easily. GPR plays an important role to find any anomalous material in salt deposit. The same concept can be used for monitoring of water flow in crystalline rock. Crystalline rock such as granite contains very little water flow in it, therefore it is also a good material for storage. At the same time, electromagnetic waves can penetrate relatively easily in this material. GPR in salt was quite successfully used, then advanced GPR systems such as directional borehole radar were also developed. In addition, salt deposits can be used for GPR experiments for fundamental understanding of electromagnetic wave propagation, and analysis of antenna performance in material.
2 citations
21 Oct 2008
TL;DR: In this paper, a rotary laser positioning system (RLPS) was used to refine the 3D-GPR images of the Satiobaru burial mounds archaeological site.
Abstract: Currently Ground Penetrating Radar (GPR) used in archaeological prospection is based on 2D parallel line methodologies characterized by line spacing ranging from 0.25m to 1m (common line separation is 0.5m) with 250MHz or 500MHz antennas and huge amount of interpolation used to fill in the data gaps. Such a 3D GPR surveys produce highly interpolated subsurface maps which do not exploit the full resolution of GPR. High resolution 3D-GPR images of the subsurface can be obtained by a quarter wavelength of grid spacing in all direction. Acquiring such a very huge and dense data using commercial GPR is not practical and data processing takes a very long time. Recently we use a new GPR system which is a combination between commercial GPR with a rotary laser positioning system (RLPS) developed by Miami University. In this paper we will show how the high density 3D-GPR data can improve the image quality and refined the subsurface archaeological structure resolution in Satiobaru burial mounds archaeological site. The GPR vertical cross-sections, horizontal depth slices and the data volume animation extracted from the full resolution 3D GPR reveal a lot of information about the past human activities most likely burial mounds. Figure 2 includes a pair of prominent structures (T1 and T2) that represents anomalies related to archaeological features. Moreover, circular scattered anomalies labeled R1 and R2 aligned into well-defined features that give indication that they are associated with subsurface archaeological features. These structures cannot be clearly detected from horizontal time slice created by the conventional 2D GPR parallel line survey. Figure 1: GPR vertical cross-section after data processing (a) From 3D GPR (b) From conventional GPR. Circle indicate the archaeological anomalies locations. Figure 2. Horizontal time slice (a) and (c) from 3D GPR with 10cm line spacing. (b) and (d) from conventional GPR lines spaced with 25cm, where many subsurface structures are almost invisible. R1 R2 (c) Image from 3D GPR at 2.49m depth (a) Profile from 3D GPR (b) Profile from Conventional GPR T1 T2 (a) Image from 3D GPR at 1.35m depth (b) Image from conventional GPR
TL;DR: Both the amplitude and the phase error have been compensated using the proposed novel compensation method based on a dispersion relation equation for the constrained interpolation profile (CIP) method.
Abstract: We propose a novel compensation method based on a dispersion relation equation for the constrained interpolation profile (CIP) method. In our method, two additional operations are performed after the CIP calculation. One is to calculate the numerical attenuation constant $\widetilde\alpha$ and the numerical phase constant $\widetilde\beta$ from the dispersion relation equation using Newton-Raphson method. The other is product and sum operations to compensate for amplitude and phase from the calculated $\widetilde\alpha$ and the $\widetilde\beta$. As described in this paper, both the amplitude and the phase error have been compensated using our method.
07 Jul 2008
TL;DR: While some discrepancies are appeared, the SPM and Oh models show agreements with absolute/relative sigma0 value in some degree, and the X-bragg model shows moderate agreement in anisotropy-ks relation.
Abstract: We performed three field experiments with PALSAR/polarimetry observations in Ulaanbaatar/Mongolia, Arctic National Wildlife Region (ANWR/ Alaska)/US, and Sendai/Japan, to evaluate soil moisture models. The PALSAR polarimetry observations with off-nadir angle of 21.5deg were done in May 4, 2007, Jul. 29, 2007, and Apr. 14, 2007 in each place. On the other hand, the field experiments were done for May 2-7, 2007, Jul. 28-Aug 4, 2007, and Apr. 14, 2007. The surface parameters derived from field measurements show large dynamic ranges, which are from 4% to 80% for soil moisture value, from 0.16 to 2.22 for surface roughness, and from 1.97 to 8.09 for correlation length. We applied SPM model, X-bragg model, and Oh model in this time. While some discrepancies are appeared, the SPM and Oh models show agreements with absolute/relative sigma0 value in some degree. The X-bragg model shows moderate agreement in anisotropy-ks relation.
Proceedings Article•
01 Oct 2008TL;DR: This paper presents a half-year evaluation test of ALIS, a hand-held dual-sensor developed for humanitarian demining that can reconstruct buried land mine images after data acquisition and drastically increases the quality of the image of the buried objects.
Abstract: ALIS is a hand-held dual-sensor developed for humanitarian demining. The dual-sensor ALIS is equipped with a metal detector and a GPR (ground penetrating radar). An unique and novel sensor tracking system, which can record the GPR and metal detector signal with its location is equipped in ALIS. Due to its sensor location information, we can reconstruct buried land mine images after data acquisition. The image reconstruction, or migration processing drastically increases the quality of the image of the buried objects. ALIS evaluation test was conducted in Croatia in October 2007. Then after, we stared a half-year evaluation test of ALIS in QC test in Croatia in December 2007. This test will be conducted in various soil and environmental conditions in Croatia.