Synthetic Aperture Radar (SAR) is a high resolution microwave sensor, but its processed data has potential noise called“speckle noise”which degrades image quality. This noise is conspicuous when the data is processed in small number of looks. In this paper, a new method for speckle reduction, CST filter, is proposed. Using a characteristics that a distribution of observed SAR data can be estimated by theoretical probability density function (pdf), this method determines whether the target pixel is a member of homogeneous target or not, then apply noise reduction only to the pixel which is a member of homogeneous target. This technique can be applied to the data processed in any number of looks. The proposed method as well as five major existing methods are applied to the simulated SAR data and the JERS-1/SAR data. By comparing all filtered images, it was confirmed that the proposed method has better ability for reproduction of homogeneous targets. Although the proposed method does not use any templates to preserve structured targets, it showed almost same performance to preserve edge and point targets as the other structure preservation filters.
The present paper proposes an accurate geometric correction method for AVHRR data. Our previous work has proposed a method, which uses the bilinear interpolation for speeding up geometric correction of AVHRR data, but there is still tiny residual error after geometric correction only using the orbital information TBUS. GCP method is the general method for improving the accuracy of geometric correction. The tendency of each orbital element and satellite reported time (satellite internal clock) for the GCP's residual error is analyzed by curve fitting method as a polynomial expression. The standard regularization method is introduced to solve the reverse problem from the GCP's residual errors to the variation of each orbital element. The residual errors in line direction and pixel direction from GCP process are smoothly changed, therefore, two-dimensional surface spline is applied to the smooth-constrained stabilizer. However, the solution from the regularization method is not the globally optimal one but the locally optimal one sometimes. Here, the orbital information TBUS is analyzed to decide the correction order of orbital elements. From this correction order, an algorithm with the polynomial expressions can be used to estimate the variation of each orbital element and satellite reported time from the GCP's residual error, when the locally optimal solution meets. Finally, some experimental results are shown to verify the proposed method, and we will conclude our proposed geometric correction method.
The Observation of two dimensional (2-D) wave parameter distribution is important for the estimation of the wave force to marine constructions, such as jetty. The in situ data routinely observed now are point data and the cost is expensive, so the number of observation point is a few. There is no routine method for monitoring 2-D wave parameter distribution. Marine radar can offer the image of 2-D wave field by monitoring the sea clutter from the sea surface. The data from marine radar is, however, analog data, so it is difficult to analyze 2-D wave parameter from the image. We are developing the data acquisition system from marine data now. Before the marine radar is calibrated by comparing in situ data, we proposed the method for monitoring 2-D wave parameter, especially wave length and wave direction, by using simulated image of marine radar in this study. Image of marine radar was simulated by FFT, when wave direction was 0, 30, 45, 60 and 90 deg. and wave length is 1/8, 1/4 and 3/8 of perimeter size of the target area. It is concluded that the accuracy of the proposed method in this study is concluded over 90% and it is accurate enough for operational use.
The process to obtain DEM (digital elevation model) from contours drawn on paper map relies on manual operations very heavily. Especially, restoration of extracted contours requires quite amount of time for human operator, and has been one of the most serious burden in the process. In the previous researches, there had been proposed several methods to reduce the burden. However, they mainly focus on the geometrical relations between individual ending points in local perspective, which resulted in very limited success. In this paper, a new restoration method based on the adjoining property between contours is proposed. In this approach, virtual elevations are assigned for each contour segments by using the fact that the adjoining contours has a same elevation or an elevation of unit difference. And by restoring the contours of same virtual elevation, the restoration efficiency could be improved quite largely. The result of experiments shows that 94% of the ending points could be restored by the proposed method, while only 52% could be restored when geometric relations between individual ending points only is used.
As SAR data have much different characteristics in their geometry and radiometry compared with those of optical sensor data, it is necessary to develop a geometric and radiometric correction method of SAR data in order to use SAR data combined with other optical sensor and a map. The author developed a secondary geometric and radiometric correction method which is applicable to SAR level 2.1 standard product. The geometric correction was performed based on a foreshortening simulation applied to a reference optical sensor image. As the radiometric correction, the influence of incidence angle on radar cross section (RCS) was considered to rectify back scatter intensity after the geometric correction. The experimental studies using JERS-1 and ERS-1 SAR data showed that the correction methods resulted in fairly precise geometric correction and reasonable radiometric improvement for JERS-1/SAR data, although there remained slightly bigger error in the geometric correction and insufficiency in the radiometric improvement for ERS-1/SAR data.
Many archeological artifacts are excavated during a year. They are drawn to ortho objective drawings by archeologists themselves and part-timer's hand with much time. In order to labor saving, ortho projections for these artifacts are currently being taken by STILL Camera. This method, however requires a great investment in time, e.g. developing or enlarging. This paper present a new system for real time ortho projection using CCD Camera.
Collecting the NOAA-HRPT data received at saveral stations in Japan in the past, the HRPT data set is produced by a standardized format. The collected HRPT data were obtained by the NOAA6, 7, 8, 9 and 10 during 1981-1988. The total number of the HRPT data is 1570. The data are stored in the optical disks with a capacity of 5 GBytes, which ensure the several ten years of the data life in the future. This paper describes the purpose and production processes of the HRPT data set, and duscusses its significance together with points at issue.