SAR Sensors Research Articles

Wide band SAR sub-band splitting and inter-band coherence measurements

Range resolution of SAR images is determined by transmitted radar signal bandwidth. Most recent SAR sensors use wide band signals in order to achieve metric range resolution, whereas metric azimuth resolution can be achieved in spotlight mode. As an example, ENVISAT ASAR sensor uses a 15-MHz bandwidth chirp whereas TerraSAR-X spotlight mode uses signals having a 150-MHz bandwidth leading to a potentially 10 times higher resolution. One can also take advantage of wide band to split the full band into sub-bands and generate several lower resolution images from a single acquisition, each being centred on slightly different frequencies. These sub-images can then be used in a classical interferometric process to measure inter-band coherence of a given scene. This inter-band coherence reveals scatterers keeping a stable-phase behaviour along with frequency shift. A simple coherence model derived from Zebker model for randomly distributed surface scatterers is proposed. Examples are presented, showing that scatterers can have a behaviour that deviates from the model, leading to a new information channel.

Surface deformation associated with the 2008 Ms8.0 Wenchuan earthquake from ALOS L-band SAR interferometry

The Ms8.0 Wenchuan earthquake (in China) occurred on 12 May 2008 as a result of slip on the northeastern-striking Longmen Shan (LMS) faults beneath the rugged margin between the Qinghai-Tibet Plateau and Sichuan Basin. The catastrophic event caused significant surface ruptures and permanent ground displacement in a wide area. This paper concentrates on mapping surface deformation caused by the main shock with the interferometric synthetic aperture radar (InSAR) technology. The coseismic interferogram covering an area of over 83,000 km2 is computed with use of 46 SAR images that were collected along 6 adjacent ascending orbits by the L-band SAR sensor onboard the Japanese Advanced Land Observing Satellite (ALOS). The displacements measured at 16 GPS sites are used to check the accuracy of the InSAR deformation measurements. The radar coherence is computed and analyzed in relation to the topography and the normalized difference vegetation index (NDVI) estimated from the Landsat-7 imagery. The results show that the coseismic surface deformation can be mapped up to a centimeter-accuracy level even over the highly mountainous and heavily vegetated area with the L-band interferometer. It is also demonstrated that the L-band interferograms with time interval of months to years can still maintain acceptable radar coherence for deformation extraction over the area under the extreme conditions. The extracted InSAR deformation measurements show that the lands in the Sichuan Basin had moved 0.1–1.3 m toward the satellite along the radar line of sight (LOS) direction with an azimuth of 349.8° and an elevation angle of 51.3°, while the lands in the LMS area had moved 1.4 m at most away from the satellite.

Surface displacement of the Mw 7 Machaze earthquake (Mozambique): Complementary use of multiband InSAR and radar amplitude image correlation with elastic modelling

In this paper we investigate the surface displacement related to the 2006 Machaze earthquake using Synthetic Aperture Radar Interferometry (InSAR) and sub-pixel correlation (SPC) of radar amplitude images. We focus on surface displacement measurement during three stages of the seismic cycle. First, we examined the co-seismic stage, using an Advanced SAR (ASAR) sensor onboard the Envisat satellite. Then we investigated the post-seismic stage using the Phase Array L-band SAR sensor (PALSAR) onboard the ALOS satellite. Lastly, we focussed on the inter-seismic stage, prior to the earthquake by analysing the L-band JERS-1 SAR data. The high degree of signal decorrelation in the C-band co-seismic interferogram hinders a correct positioning of the surface rupture and correct phase unwrapping. The post-seismic L-band interferograms reveal a time-constant surface displacement, causing subsidence of the surface at a ∼5cm/yr rate. This phenomenon continued to affect the close rupture field for at least two years following the earthquake and intrinsically reveals a candidate seismogenic fault trace that we use as a proxy for an inversion against an elastic dislocation model. Prior to the earthquake, the JERS interferograms do not indicate any traces of pre-seismic slip on the seismogenic fault. Therefore, slip after the earthquake is post-seismic, and it was triggered by the Machaze earthquake. This feature represents a prominent post-seismic slip event rarely observed in such a geodynamic context.

The Importance of Soil Moisture and Soil Structure for InSAR Phase and Backscatter, as Determined by FDTD Modeling

In this paper, we introduce a finite-difference time-domain simulator that accurately models the interaction of microwaves with realistic soils, specifically from spaceborne interferometric synthetic aperture radar (InSAR). The modeled soils are characterized by surface roughness, correlation length, bulk moisture content, vertical moisture gradient, and small air-filled-void content. Simulation results include both backscatter and interferometric phase, and we are particularly interested in assessing the potential of the latter as a proxy for soil moisture. We find that differences in homogeneous bulk moisture result in only small phase differences (< 5?). In contrast, combinations of vertical moisture gradients and small air-filled voids, which may typically exist in more realistic soils, can produce phase changes > 30? for HH and > 50? for VV when the soil moisture is varied from 3% to 30% in the uppermost 2 cm of the soil. Phase changes of this magnitude are easily detectable by spaceborne InSAR techniques. While a strong phase response to a change in mean bulk moisture is common to vertical moisture gradient and small air-filled-void cases, their corresponding backscatter responses are very different. A vertical moisture gradient makes the backscatter response dramatically flatter compared with the case of uniform moisture; in contrast, the introduction of air-filled voids barely alters the backscatter. Thus, it may be possible to infer near-surface soil-structure parameters such as vertical gradients or fractions of voids and inhomogeneities from combined SAR phase and backscatter data. Future SAR sensors could be optimized for this purpose. Prior theoretical work based on the assumption of vertically uniform soil-moisture distributions may need to be adjusted, and the lack of a theory that accommodates more complex soil structures may explain why backscatter inversions have yet to result in a viable operational system.

RESEARCH ON TECHNOLOGY DEVELOPMENT FOR FISHING VESSELS IDENTIFICATION BY SATELLITE REMOTE SENSING - STATUS IN DEVELOPED COUNTRIES AND JAPANESE PATROL SYSTEM

Current status and trends ov vessel detection, identification technology development and application in major countries were surveyed. According to increasing the number of foreign poaching and suspicious vessels intrusion into EEZ, patroliling by vessel and airplane does not satisfy the needs because of narrow coverege and observation frequncey. The satellite monitoring by SAR and optical sensor has been studied and partially used, but there are several disavantages such as observation frequncy, geometric occuracy and weather dependence to adopt for operational use. This paper describes an optimize system for vessel detection and identification by combining patrolling vessel, airplane and satellite. Keyword: vessel identification by satellite image, IKONOS visible image, JERS-1, Synthetic Apature Reader

Space-borne polarimetric SAR sensors or the golden age of radar polarimetry

SAR Polarimetry represents an active area of research in Active Earth Remote Sensing. This interest is clearly supported by the fact that nowadays there exists, or there will exist in a very next future, a non negligible quantity of launched Polarimetric SAR Spaceborne sensors. The ENVISAT satellite, developed by ESA, was launched on March 2002, and was the first Spaceborne sensor offering an innovative dualpolarization Advanced Synthetic Aperture Radar (ASAR) system operating at C-band. The second Polarimetric Spaceborne sensor is ALOS, a Japanese Earth-Observation satellite, developed by JAXA and was launched in January 2006. This mission includes an active L-band polarimetric radar sensor (PALSAR) whose highresolution data may be used for environmental and hazard monitoring. The third Polarimetric Spaceborne sensor is TerraSAR-X, a new German radar satellite, developed by DLR, EADS-Astrium and Infoterra GmbH, was launched on June 2007. This sensor carries a dual-polarimetric and high frequency X-Band SAR sensor that can be operated in different modes and offers features that were not available from space before. At least, the Polarimetric Spaceborne sensor, developed by CSA and MDA, and named RADARSAT-2 was launched in December 2007 The Radarsat program was born out the need for effective monitoring of Canada’s icy waters, and some Radarsat-2 capabilities that benefit sea- and river ice applications are the multi-polarization options that will improve ice-edge detection, ice-type discrimination and structure information. The many advances in these different Polarimetric Spaceborne platforms were developed to respond to specific needs for radar data in environmental monitoring applications around the world, like : sea- and river-ice monitoring, marine surveillance, disaster management, oil spill detection, snow monitoring, hydrology, mapping, geology, agriculture, soil characterisation, forestry applications (biomass, allometry, height…), urban mapping etc…. In order to promote the exploitation of Polarimetric Spaceborne data, as it is starting today to proliferate with the launch of these Polarimetric SAR sensors, the PolSARpro Software, developed under contract to ESA and that is a toolbox for the scientific exploitation of Polarimetric SAR and Polarimetric-Interferometric data and a tool for high-level education in radar polarimetry, has been expanded and refined to include all elements necessary for the demonstration of a number of key applications. The PolSARpro Software, that already was supporting an important range of airborne and spaceborne polarimetric data sources, supports now the following additional data sources: ALOS-PALSAR (Dual-Pol fine mode and Quad-Pol mode), TerraSAR-X (Dual-pol mode) and Radarsat-2 (Dual-Pol fine mode and Quad-Pol fine and standard modes), by offering a platform dedicated interface for E.O Scientific Investigator. A number of illustrations of key applications has been developed for the demonstration and the promotion of the Polarimetric Spaceborne missions, that are consistent with the activities incorporated in the GMES Services Element (GSE). The aim of this communication is to present the current state of the art in SAR Polarimetry ranging from theory to applications, with special emphasis in the analysis of data provided by the new Polarimetric Spaceborne SAR sensors, and samples of real polarimetric data will be presented for use in real-life examples of key applications.

Multi-mode SAR Interferometry Processing Research and Implementation

Current operation mode of SAR can be roughly divided into two types: strip-map mode and burst mode. The most conventional mode is strip-map mode, in which the swath width is quite limited. The other type is burst mode, which is an active option to overcome this limitation by cyclically scanning several subswaths, known as ScanSAR. In addition, Envisat ASAR has another type of burst mode, that is, Alternating Polarization mode. ALOS PALSAR and Radarsat-1 also have their own ScanSAR operation modes, but each of them is distinctive from the others in implementation. Numerous theoretical results and applications of interfer- ometry using strip-map data have been published before. Interferometry with burst mode data, however, is much rarer and difierent from the case of the traditional strip-map mode from raw data focusing to interferogram generation because of its burst nature of data acquisition pattern. In our study, we put our emphasis on each kind of burst mode interferometry and mixed mode interferometry. Until now, our successful research work includes Envisat ASAR WS-WS, IM-WS and ALOS PALSAR WB1-WB1 Interferometry. Other development activities including Envisat AP-AP and Radarsat-1 SNA-SNA interferometry are still on going. In the following paper, we will present our results and give an overview of multi-mode SAR interferometry for the present spaceborne SAR sensors.

Imaging of Moving Targets With Multi-Static SAR Using an Overcomplete Dictionary

This paper presents a method for imaging of moving targets using multi-static SAR by treating the problem as one of spatial reflectivity signal inversion over an overcomplete dictionary of target velocities. Since SAR sensor returns can be related to the spatial frequency domain projections of the scattering field, we exploit insights from compressed sensing theory to show that moving targets can be effectively imaged with transmitters and receivers randomly dispersed in a multi-static geometry within a narrow forward cone around the scene of interest. Existing approaches to dealing with moving targets in SAR solve a coupled non-linear problem of target scattering and motion estimation typically through matched filtering. In contrast, by using an overcomplete dictionary approach we effectively linearize the forward model and solve the moving target problem as a larger, unified regularized inversion problem subject to sparsity constraints.

Estimation of surface soil properties in peatland using ALOS/PALSAR

By examining the area of the Sarobetsu Mire in northern Japan using ALOS/PALSAR data, we have clarified the backscattering behavior and characteristics of the L-band microwaves when used in the study of peatlands. We classified the vegetation into six categories and noted the differences in scattering intensity and incident-angle dependencies among these. The scattering intensity for HH and HV polarizations was greatest with sasa (dwarf bamboo) and reeds, and least with sphagnum. The incident-angle dependency with the HH polarization was higher for sasa and reed than for other vegetation types. Analysis of the polarization revealed that such differences among vegetation classes were reflected most clearly in the volume scattering characteristic. Applying simple and multiple regression analysis for the environmental factors of soil, hydrology, vegetation, and roughness against the backscatter coefficient, we also found stronger interrelations with soil factors such as bulk density, nitrogen and carbon content, and C/N ratio, and against the backscatter coefficient, than with either the roughness or vegetation. Based on such results, we clarified the unique scattering characteristics of peatlands in which scattering from the surface soil is more marked than that from other elements. We consequently estimated the spatial distribution of surface soil characteristics in peatland using the combined data available from L-band satellite SAR, aircraft laser (airborne LiDAR), and optical sensors.

Crustal deformation in Australia measured by satellite radar interferometry using ALOS/PALSAR imagery

The Advanced Land Observing Satellite (ALOS), launched on 24 January 2006, is a Japanese satellite carrying an L-band SAR sensor, namely the PALSAR, which is expected to demonstrate good performance in applications such as crustal deformation measurement, subsidence detection and landslide monitoring. This paper describes a case study of Differential Synthetic Aperture Radar Interferometry (DInSAR) using ALOS/PALSAR data to detect crustal deformation caused by a recent small earthquake in Western Australia.

Feature Extraction and Visualization of Bridges Over Water From High-Resolution InSAR Data and One Orthophoto

Modern airborne SAR sensor systems provide geometric resolution in the order well below half a meter. By SAR interferometry from pairs of such images, DEM of the same grid size can be obtained. In data of this kind, many features of urban objects become visible, which were beyond the scope of radar remote sensing only a few years ago. However, because of the side-looking SAR sensor principle, layover and occlusion issues inevitably arise in undulated terrain or urban areas. Therefore, SAR data are difficult to interpret even for senior human interpreters. Furthermore, the quality of the InSAR DEM may vary significantly depending on the local topography. In order to support interpretation, SAR data are often analyzed using additional complementary information provided by maps or other remote sensing imagery. In this paper, object feature extraction and visualization from high-resolution InSAR data and one orthophoto is discussed for the example of a scene containing several bridges over water. Bridges are key elements of man-made infrastructure. Monitoring of these important connecting parts of the traffic network is vital for applications such as disaster management or in the context of political crisis, for instance, to evacuate inhabitants and to deliver goods and equipment. Aims of the approach are to derive key features of the bridge's geometry from the complementary data sources, to determine the water level, smooth the noisy InSAR DEM data, especially at water surfaces, and, finally, to generate an improved 3-D visualization of the scene by overlapping the optical image on the InSAR DEM.

Classifying Multilevel Imagery From SAR and Optical Sensors by Decision Fusion

A strategy for the joint classification of multiple segmentation levels from multisensor imagery is introduced by using synthetic aperture radar and optical data. At first, the two data sets are separately segmented, creating independent aggregation levels at different scales. Each individual level from the two sensors is then preclassified by a support vector machine (SVM). The original outputs of each SVM, i.e., images showing the distances of the pixels to the hyperplane fitted by the SVM, are used in a decision fusion to determine the final classes. The fusion strategy is based on the application of an additional classifier, which is applied on the preclassification results. Both a second SVM and random forests (RF) were tested for the decision fusion. The results are compared with SVM and RF applied to the full data set without preclassification. Both the integration of multilevel information and the use of multisensor imagery increase the overall accuracy. It is shown that the classification of multilevel-multisource data sets with SVM and RF is feasible and does not require a definition of ideal aggregation levels. The proposed decision fusion approach that applies RF to the preclassification outperforms all other approaches.

A controlled experiment to retrieve freshwater ice characteristics from an FM-CW radar system

Abstract A controlled experiment was conducted at the Cold Region Research and Engineering Laboratory (CRREL) facilities for retrieving freshwater ice characteristics using a Frequency Modulated Continuous Wave (FM-CW) radar system. The purpose of this study is to quantify the interactions between a backscattered radar signal and ice cover characteristics such as thickness and air bubble content; and to provide a comprehensive data set for testing a theoretical radar backscattering model currently under development. The experiment was held in an indoor test basin (36.5 m × 9.4 m × 2.5 m), where an ice sheet was grown from 0 to 24 cm thickness and monitored with a series of radar and geophysical measurements. Backscattering of the ice cover using an in-house FM-CW C-band radar was repeatedly measured at incidence angles varying from 0 to 50° for four polarisation combinations, HH, VV, HV, and VH. Ancillary data, such as ice thickness, crystalline structure and air bubble content, air temperature and hoarfrost water equivalent were collected to support the analysis and interpretation of the radar data. Analysis of the radar backscattered signal indicates that the received power is notably affected by ice thickness. For example, the HH/HV ratio of power signals correlated with ice thickness between 8 and 24 cm with R 2 value ranging from 0.75 to 0.90. It was shown through modeling of the radar reflectivity that the lack of correlation at less than 8 cm was caused by the coherent addition of the multiple reflections at the air/ice and the ice/water boundaries. These results are encouraging as for the potential of retrieving lake and river ice thickness from satellite SAR sensors operating at C-band frequencies and at 20 to 50° incidence angles, such as Radarsat 1 and 2 and Envisat, although their current radiometric resolution may limit ice thickness retrieval to thicker ice covers. Also, a number of unresolved issues must be addressed before taking full advantage of these sensors for operational retrieving of freshwater ice thickness. For one, additional controlled experiments must be carried out with ice covers embracing a range of surface roughness values. Ice covers with more diversified air inclusions and snow cover characteristics also need to be investigated, which probably can be best done by deploying radar systems next to natural ice covers.

Operational performance of current synthetic aperture radar sensors in mapping soil surface characteristics in agricultural environments: application to hydrological and erosion modelling

AbstractSynthetic aperture radar (SAR) sensors are often used to characterize the surface of bare soils in agricultural environments. They enable the soil moisture and roughness to be estimated with constraints linked to the configurations of the sensors (polarization, incidence angle and radar wavelength). These key soil characteristics are necessary for different applications, such as hydrology and risk prediction.This article reviews the potential of currently operational SAR sensors and those planned for the near future to characterize soil surface as a function of users' needs. It details what it is possible to achieve in terms of mapping soil moisture and roughness by specifying optimal radar configurations and the precision associated with the estimation of soil surface characteristics.The summary carried out for the present article shows that mapping soil moisture is optimal with SAR sensors at low incidence angles (&lt;35 ). This configuration, which enables an estimated moisture accuracy greater than 6% is possible several times a month taking into account all the current and future sensors. Concerning soil roughness, it is best mapped using three classes (smooth, moderately rough, and rough). Such mapping requires high‐incidence data, which is possible with certain current sensors (RADARSAT‐1 and ASAR both in band C). When L‐band sensors (ALOS) become available, this mapping accuracy should improve because the sensitivity of the radar signal to Soil Surface Characteristics (SSC) increases with wavelength. Finally, the polarimetric mode of certain imminent sensors (ALOS, RADARSAT‐2, TerraSAR‐X, etc.), and the possibility of acquiring data at very high spatial resolution (metre scale), offer great potential in terms of improving the quality of SSC mapping. Copyright © 2007 John Wiley &amp; Sons, Ltd.

고해상도 레이더용 광대역 디지털 첩 펄스 발생기 실험모델 개발

항공기나 위성에 탑재되어 지표면의 영상을 획득하기 위한 합성 개구 레이더의 영상 분해능은 거리 방향 분해능(Range Resolution)과 이에 수직한 방향의 분해능(Azimuth Resolution)으로 구분할 수 있다. 레이더 센서를 이용한 영상의 해상도를 향상시키기 위해서는 신호처리를 위한 첩 펄스를 광대역화 할 필요가 있으며, 본 논문에서는 고해상도의 영상을 획득 할 수 있는 디지털 첩 펄스 발생기를 설계하였다. 디지털 첩 펄스 발생기는 크게 AWG방식과 DDS방식으로 구분할 수 있으며 본 연구에서는 DDS방식의 첩 펄스 발생기로 선형 주파수 변조(LFM) 파를 발생시키는 300MHz 대역의 광대역 디지털 첩 펄스 발생기를 개발하였다. 개발된 첩 펄스 발생기는 거리 방향 분해능이 50cm 이상 되는 고해상도 영상 레이더 시스템을 구현할 수 있는 성능을 가진다. There are range and azimuth direction resolution of synthetic aperture radar on the aircraft or satellite. Wide bandwidth chirp pulse generation technology is prerequisite for SAR image with fine resolution. There are two kinds of digital chirp pulse generation technology as arbitrary waveform generator(AWG) and direct digital synthesizer(DDS). In this paper, we design and implement a digital chirp pulse generator to generate 300MHz wide bandwidth linear FM chirp pulse for the fine resolution image with direct digital synthesizer. Implemented chirp pulse generator can be useful for the SAR sensors to make 50cm range resolution image.

Improving Urban Road Extraction in High-Resolution Images Exploiting Directional Filtering, Perceptual Grouping, and Simple Topological Concepts

In this letter, the problem of detecting urban road networks from high-resolution optical/synthetic aperture radar (SAR) images is addressed. To this end, this letter exploits a priori knowledge about road direction distribution in urban areas. In particular, this letter presents an adaptive filtering procedure able to capture the predominant directions of these roads and enhance the extraction results. After road element extraction, to both discard redundant segments and avoid gaps, a special perceptual grouping algorithm is devised, exploiting colinearity as well as proximity concepts. Finally, the road network topology is considered, checking for road intersections and regularizing the overall patterns using these focal points. The proposed procedure was tested on a pair of very high resolution images, one from an optical sensor and one from a SAR sensor. The experiments show an increase in both the completeness and the quality indexes for the extracted road network

Integration of 3D data in SAR mission planning and image interpretation in urban areas

Abstract State-of-the-art airborne SAR sensors provide high-resolution ground mapping data. This offers the opportunity of using this technology for the analysis of built-up areas. However, especially at building locations different SAR specific phenomena like layover, shadow, and multipath-propagation burden the interpretation of the SAR imagery even for experts. In order to consider such effects in the analysis and the geocoding of SAR data, high-resolution information about the 3D structure of the urban scene is required. Three dimensional elevation data from a GIS can be provided in different representations, like DEM (raster data) or city models (vector data). In this paper, the benefit of GIS data for the SAR mission planning and the analysis of acquired SAR data are discussed. For the first task, the SAR acquisition parameters are optimized a priori with respect to the best mapping of a local area or a certain object class. For this optimization, a large number of simulations with systematically varying aspect and viewing angles are carried out. For the second task, the 2D and 3D context information are fused with the acquired SAR imagery to support the interpretation for a change detection task. Additionally, simulated features of man-made objects are offered to the image interpreter for comparison with the data. The feasibility of different kinds of GIS data for these purposes is discussed.

Land use mapping with evidential fusion of features extracted from polarimetric synthetic aperture radar and hyperspectral imagery

Abstract As part of the Earth Observation Application Development Program (EOADP) program sponsored by the Canada Space Agency, Lockheed Martin Canada––in partnership with Defense Research and Development Canada––has initiated a study aiming at studying the exploitation of the synergy between polarimetric SAR and hyperspectral imagery with the development of a system prototype called Intelligent Data Fusion System (IDFS). This system, based on the evidential fusion of features extracted from each type of imagery, is made of three modules. The polarimetric SAR module contains polarimetric classifiers, textural classifiers to provide hypotheses related to the textural and scattering properties of the illuminated area. The hyperspectral module contains an end-members selection technique and a collection of spectral indices. Each feature giving an incomplete representation of an object of interest, it is expected that the combination of complementary, redundant features will contribute to reduce the false alarm rate, improve the confidence in the target identification and the quality of the scene description as a whole. The combination of information provided by each feature extractor is performed according to the theory of evidence (Dempster–Shafer) in the third module. This paper presents an overview of the current functionality of IDFS. First results of evidential fusion are shown for land use mapping. Data sets were acquired over Indian-Head (Saskatchewan) with an airborne C-band polarimetric SAR and HSI Probe-1 sensors and were provided by the Canada Center for Remote Sensing.

AVALIAÇÃO DA ESTEREOSCOPIA SAR (STANDART-RADARSAT-1) E HÍBRIDA (STANDART-RADARSAT-1 &amp; TM-LANDSAT-5) EM MAPEAMENTO GEOLÓGICO NA PROVÍNCIA MINERAL DE CARAJÁS

This paper discusses the theoretical and practical aspects related to SAR and hybrid sensors (VIR - Visible-Infra Red x SAR - Synthetic Aperture Radar) stereoscopies, and their performance for geological mapping in the Amazon Region. Stereo Standard-RADARSAT-1 (S5D x S7D) and hybrid Standard-RADARSAT-1/TM-Landsat-5 (S7D x TM4) were visually evaluated aiming at geological mapping in the Carajás Mineral Province. The stereo SAR pair has shown large differences in radiometric and geometric properties when compared to the VIR x SAR stereo pair. The investigation has also demonstrated that these differences play a key role in the extraction of geological information and also confirmed that previous background in SAR and radargrammetry are fundamental issues in the composition and interpretation of the SAR and hybrid products. The research has indicated the greater potentiality of the VIR x SAR product when compared to the SAR stereoscopy. The complementary nature of the information provided by both sensors in distinct region of the electromagnetic spectrum was a fundamental cause for this better performance.

Avaliação da estereoscopia sar (standart-radarsat-1) e híbrida (standart-radarsat-1 & tm-landsat-5) em mapeamento geológico na Província Mineral de Carajás

This paper discusses the theoretical and practical aspects related to SAR and hybrid sensors (VIR - Visible-Infra Red x SAR - Synthetic Aperture Radar ) stereoscopies, and their performance for geological mapping in the Amazon Region. Stereo Standard-RADARSAT-1 (S5D x S7D) and hybrid Standard-RADARSAT-1/TM-Landsat-5 (S7D x TM4) were visually evaluated aiming at geological mapping in the Carajas Mineral Province. The stereo SAR pair has shown large differences in radiometric and geometric properties when compared to the VIR x SAR stereo pair. The investigation has also demonstrated that these differences play a key role in the extraction of geological information and also confirmed that previous background in SAR and radargrammetry are fundamental issues in the composition and interpretation of the SAR and hybrid products. The research has indicated the greater potentiality of the VIR x SAR product when compared to the SAR stereoscopy. The complementary nature of the information provided by both sensors in distinct region of the electromagnetic spectrum was a fundamental cause for this better performance.